摘要:

80 LAWES AND GILBXRT ON THE COMPOSITION VALUE XI.-On the Composition Value and Utilization of Town Sewaye." By J. B. LAWES,Esq. F.R.S. F.C.S. and J. H. GILBERT Ph.D. F.R.S. F.C.S. Position of the Sewage Question. ITis no less true than strange that after somany centuriesof advance in regard to almost every other requirement of civilised life the lesson should not yet have been learnt of how to dispose of the excretal matters of large populations in such a manner as to secure both their collection and removal without nuisance and injury to * The substance of this paper was given as a discourse before the Chemical Society February 1 1866 by Dr. Qilbert. AND UTILIZATION OF TOWN SEWAGE health and their economical utilization for the reproduction of food.But it is undoubtedly the fact that hitherto where utilization has been the most complete comfort and health have generally been in the greatest degree sacrificed and where on the other hand the refuse matters of town populations have been the most rapidly and perfectly removed from their dwellings there has been either no utilization at all or it has been most imperfectly attained. Sew age the foul stream which flows through the underground veins and arteries of our great cities carrying with it the excretal and other refuse matters of large populations hitherto to little better purpose than to be wasted and to be a source of pollution to our rivers-to destroy their fish injure their channels and render them unfit as a water-supply to other towns-is the product of the to us modern but in the history of the world onlyresuscitated and elaborated water-system of town purification.There is no doubt that excretal and other refuse matters are removed from habi-tations more rapidly with less nuisance to the occupants and with less injury to their health by means of water than in any other way hitherto practised on a large scale. But such is the dilemma into which the progress of modern civilisation in this direction has brought us in this country so far as utilization and the condition of our rivers are concerned that some authorities especially on the Continent incline to the reactionary conclusion that a return to the cesspool system or rather the adoption of some improved barrel tank or cesspool system of collection and removal without admixture with extraneous water is inevitable.Before therefore entering upon the question of the composition value and modes and results of' the utilization of dilute town sewage it will be well to call attention though very briefly to some of the results of experience hitherto attained under other systems of town purification and other modes of utilizatiou of the products than the modern ones by means of water. China and Japan are frequently citd as affording examples of very perfect utilization of human excretal matters and as a con-sequence of great productiveness of the soil and great concen-tration of population on a given area of land. The manner of collecting removing and transporting human excretal matters in those countries is however such as to be quite inadmissihle with our modern notions of cleanliness decency comfort and health It is frequently stated that in Belgium human excretal matters are very perfectly utilized and realise considerable money return 82 LAWES AND GTLBERT ON THE COMPOSITION VALUE to the town populations.Indeed in one of the applications made only last year to the Metropolitan Board of Works for the conces- sioii of the Southern sewage of the Metropolis and still under the consideration of that body it is stated that the excretal matters sell in Belgium for something over &1per person per annum. There is no doubt that in some parts of Belgium the solid and a portion of the fluid excrements of the town poptilations are collected as free as possible from extraneous water in receptacles of more or less perfect construction and periodically removed for application to the land and that the land so fertilised is very pro-ductive.From observation and inquiry made in some of the towns in question it may however be safely affirmed that the practices adopted are attended with at any rate so much of nuisance and discomfort as would not now be permitted in this country; whilst it would appear that a considerable proportion of the urine of the populations escapes collection and utilization. As the result of the same inquiries it was concluded that in no case did the town population realise by the disposal of their excretal matters as much as averaged one franc per head per annum.The conclusion that as a rule but little and frequently nothing is realised by town populations when their excretal matters are collected under more or less modified cesspool or tank systems as free as possible from extraneous water and so removed for appli-cation to the land is fully confirmed by the results of an inquiry conducted by a Commission sent out by the Prussian Government in 1864 to investigate the modes of coliection removal and utili- zation in various localities with a view to the adoption of improved plans for the city of Berlin. The Prussian Commissioners Herreu C. v. Salviati 0. Roder and Dr. Eichhorn visited and reported upon not only the Belgium towns of Ghent Ostend and Autwerp hut likewise Hanover Cologne Metz Carlsruhe Strasburg Basle Lyons Zurich Munich Nurernberg Dresden and Leipzig ; and their report shows riot only that the householders seldom realised any- thing like a franc per head per annurn for their excretal matters but that in the majority of cases it cost them something for the removal.Nevertheless looking to the position and local circum- stances of Berlin and especially to the results of the water-system in this country hitherto the Commissioners deprecate the adop- tion of that system for that city and recommend more perfect arrangements and more stringent regulations for the emptying AND UTILIZATION OF TOWN SEWAGE. and removal of the contents of existing cesspools and where practicable the adoption of a system under which the excretal matters of each house are to be collected in a barrel placed at the bottom of the shaft leading from the closets which when removed is covered with a closely fitting lid and is of such dimensions that two men can carry it by means of handles attached for that pur- pose.They seem to anticipate little if any pecuniary profit to the town from these arrangements but consider that they will be attended with scarcely any or even no nuisance or discomfort and that by their means a large amount of valuable manure will be provided in a convenient form for transport and utilization. There can however we think be little doubt that under such a system the collection and removal must be attended with con-siderable nuisance that the greater part of the urine mill be lost and that the cost of the collection removal and transport will be such as to render the utilization unprofitable beyond a compara-tively limited distance from the city.There is little probability that the difficulties of the water-system will lead us in this country to have recourse again in our large towns to any system of cess-pools tanks or barrels however improved; but it may be well here to notice one or two attempts that have been made within the last few years to obviate the use of water and thereby to avoid the pollution of rivers and to secure the coilection of the manurial matters in a form more readily transportable by ordinary means and therefore more appli- cable for general agricultural use for there cannot be a doubt that if any system could be devised by which human excretal matters could be collected and removed from dwellings without either nuisance or injury to health and obtained economically in a con- centrated dry and portable condition their utilization would be much more perfectly attained by such means than is at a11 likely or even possible under the water-system.Perhaps the most noticeable attempt of the kind in question is that which has been made at Hyde in Lancashire a manufactur- ing town of more than 20,000 inhabitants. Some few years ago a company contracted to carry out what they call the ‘‘ Eureka system.” They provided boxes to fit in at the back of the privy or closet of nearly every house leaving scarcely a water-closet in the place.Some disinfecting or deodorising mixture is put into the box before it is placed in its position and the box is excha~lged for a fresh one after a certain number of days according to the 84 LAWES AND GILBERT ON THE COMPOSITION VALUE number of individuals frequenting the place; and it is stipulated that neither extraneous water nor any other than human excretal matters should be accumulated in these receptacles. The bDxes when removed are covered with closely fitting lids and so trans-ported in closed vans to a manure manufactory close to the town. Here the matters are first well mixed and then strained to remove rags which are washed and sold for paper-making. More disin- fectant is then added and the matter concentrated by distillation the distilled water being sold to dyers and bleachers.The residue thus thickened is theri mixed with coal-ashes which are collected in the houses in casks left for the purpose and before being used are re-burnt in a reverberatory fnrnace and finely ground. On visiting Hyde in 1863 it certainly appeared that the mode of collection and preparation adopted was attendetl with at any rate very little unpleasant odour and it was maintained by the advocates of the system that its adoption had been successful in a sanitary point of view ;though even at that time some difference of opinion existed aud a controversy on the subject was in progress. The system is still in operation; but we are informed that the feeling of the inhabitants is very Rtrong against the main- tenance of the works in the neighbourhood; indeed that an injunction against them has been sought though unsuccessfully and that proceedings by indictment are now being taken.This opposition has reference not to the mode of collection but to the conducting of the manufacture so near to the town But whether or not the plan of collection and removal may have proved successful so far as the avoidance of nuisance and injury to health are concerned the process of manufacture seems unfortunately to offer but little prospect of successful utilization so far at least as can be judged from the results of an analysis made at Rothamsted of a sample of the manure obtained direct from the works. It was found to contain only between I and 2 per cent.of ammonia. Such a manure although it might be useful enough when applied in quantities of many tons to the acre would obviously be not worth more than its carriage beyond thedistance of a very few miles. Besides the great dilution of the more valnable manurial matters by the admixture with ashes a little consideration of the habits of the people is sufficient to account for the small quantity of ammonia found in tlle manure; for it is obvious that little of the urine beyond that passed ouce a day with the faxes would reach the AND UTILIZATION OF TOWN SEWAGE. boxes and so find its way into a manure thus collected and pre- pared. One more dry system the offspring of the difficulties of the wet one should be briefly noticed namely that of the Rev.Mr. Moule. Mr. Moule has invented and patented an arrangement for the use of dry sifted earth instead of water. He states that by the use of about 41bs. per head per day of finely sifted clay deposited by means of a mechanical arrangement upon the fzecal matters as soon as passed they are at once entirely deodorised and in a few weeks are so entirely disintegrated that neither excretal matters nor paper can be detected. in the mass which he says looks and smells like fresh earth and may after reeifting bere-used until it has done duty four times over by which of course there is not only a great saving of material but the value of the manure is considerably increased. Very obvious objections to such a system are-the difficulties of the supply and preparation of the soil in the case of towns or even in the country in wet seasons; the fact that but little of the urine containing as it does so large a proportion of the valuable manurial constituents of human excretal matters wouid reach the compost so prepared; and that in the manure produced the more valuable matters would be diluted with so large a proportion of compara- tivelj useless material that beyond a very short distance the cost of carriage would be all that the manure was worth.On the other hand that the adoption of such a system would be a great irnprove- ment in a sanitary point of view in the cases of sick rooms detached houses or even villages where the water-system is not available and that it might be even economical where the earth for preparation and absorption and the land for utilization are in close proximity may perhaps be readily granted.But we are cer- tainly not so sanguine as the Rev. Mr. M ou'te who seems to think that with the aid of Earth-closet Companies his plan is as prac- ticable for large towns as is the supply of water gas and coal at present and much more so than the removal and utiiization of dilute town sewage. Whilst it must be admitted that the agricultural utilization of human excretal matters has hitherto been much more completely attained under the system of collection without water tharl under our new one with it it must riot be forgotten that neitl~er on the continent of Europe nor in this country has such utilization resulted in any substantial profit to the towns; and that it is with VOL.XIX. H 86 LATVES AND GILBERT ON THE CONPOSITION VALUE the recorded results of China and Japan before us and after so many centiiries of experience nearer home of at least comparatively successful utilization that the old systems have been abandoned as utterly inconsistent with advance in habits and notions of cleanliness and with the maintenance of the comfort and health of large popnlations. Nor do the modifications of the dry systems to which brief reference has been made seem to hold out any hope of general and permaiient applica bihty to large populations looking as me must to the combined requirements of convenience comfort health and utilization.Our mhter-system of house defecation and town cleansing is on the other hand scarcely more than a generation old. By its means excretal and other refuse matters are more rapidly removed from dwellings than is possible by any other ; and independently of the increased comfort and freedom from nuisance obvious to all sanitary statistics hare abundantly shown increased immunity from zy motic diwases and increased longevity as the result of the adoption of that system. True it is that these advantages have hitherto been attained at the cost of the almost universal sacrifice of the manure and of great injury to our rivers. This then is admittedly the existing dilemma of our modern practices. But public attention is now so thoroughly directed to the subject that little fear need be entertained that either the systematic non-utilization of the sewage or the pollution of our rirers by it will long be permitted.Least of all is it reasonable to find discouragement in the fact that the system which hasdone so much for some of our town populations in so short a time should not at this early stage of its trial have accomplished all that might be desired or to conclude that the nuisances and diffi- culties incident to the old plans which have remained unremedied through so many centuries have much better chance now than formerly of being successfully obviated. Assuming that there is more likelihood of the general appli- cability success and permanence of the water than of any other sptem of urban defecation it becomes irnportztht to consider the composition the value and the modes and results of the utiliza- tion of the product of that system namely dilute town sewage.Many plans have been proposed for the separation of the valu- able constituents from sewer-water and the manufacture of them into dry and easily portable manure. But whilst several of these plans have been successful in separating the whole of the insoluble AND UTlLIZATION OF TOWN SEWAGE. or sedimentary matter and even some small portion of the soluble constituents leaving the fluid to a great extent or at any rate temporarily purified and in a much less objectionable condition for turning into rivers none have succeeded in either adequate or permanent purification OF in the.separation of the more valuable manurial matters and the production of a concentrated solid sewage-manure having a sufficient value to be remunerative and to bear the cost of transport more than a very €ew miles ;* nor when we consider the great solubility of some of the more active manurial constituents of sewage and the great dilution of them in the sewage can any hope be held out of so desirable a consurn-rnation ;-desirable indeed €or if human excretal matters the residue of the constituents consumed as food cannot be recovered in the form of a concentrated dry and easily transportable manure little hope can be entertaincd of their re-distribution over anything like the area from which they came or of their general use for the direct reproduction of the varied descriptions of food which were their source.The questions arise What is the amonnt and what approxi- mately the money value for the purposes of manure of the con- stituents contributed to sewage by a given population ? What their state of dilution in sewer-water? To what soils and crops is dilute sewage the most applicable ? What is the money-value realisable in practice by sewage utilization? What are the conditions of profit or loss to towns of such utilization? Composition and Value of Town Sewage. It is one thing to determine the amount of constituents con- tained in sewcge or contributed to it by 8 given population and to estimate their value accordingly as if they existed in the dry and portable condition of the various concentrated manures of known value in the market ; but it is obviously quite another to settle the really available or realisable value of the same consti-* For information in regard to some of the plans proposed for the partial purifi- cation of sewage-water or for the separation of a solid manure from it see-“ On the A4pplication of Sewage to Agriculture,” by Dugald Campbell Esq.F.C.S. Chem. Soc. Qu. J. vol. x,p. 212. “Report of Chemical Investigations relating to Metropolitan Main Drainage Question,” by A. W. H ofmaun LLD. F.R.S. and Henry M. W i tt F.C.S. Report on Metropolitan Drainage 1851. Deodori-zation of Sewage Second Report of the Royal Sewage Commission 1862. Appendix No. 6 p.. 64. 13 2 88 LAWS AND GILBERT ON THE COMPOSITION VALUE tuents when they are distributed through an enormous volume of water and if they must be transported and utilized in that condition.Let us first consider what may be called the theoretical value of the constituents of sewage or their estimated value taking as the measure the value of the same constituents in dry and portable manures. Numerous authorities have undertaken the consideration of this question and two chief methods have been adopted. One of these has been to take samples of sewage and determine its composition by analysis to adopt such estimqtes as are at comniand relating to the amount of sewage available within a given time or from a given population and so to reckon the amount and value of the constituents in a given quantity of sewage or per head or for a given number of persons per annum.Another is to base the calculation upon the amounts of faxes and urine or of the various constituents of these which have been recorded as voided by individuals of different sexes and ages-sometimes making allowance and sometimes not doing so for other than human excretal matters reaching the sewers. First as to the results attained when the calculation is based upon the analysis of sewage and estimates of the amount of it yielded by a given population. In estimates of the value of the constituents of sewage about three-fourths of the total value has generally been attributed to the ammonia (or nitrogen reclconed as ammonia) ;aid it so happens that if a value of 8d.be put upon every lb. of ammonia shown by analysis to be contained in sewage or if for each grain of ammonia per gallon a value of one farthing be given to the total constituents in I ton of' the sewage the result will in either case agree almost exactly with that obtained by the elahorate method of giving the currently adopted market values to the several constituents taking dry and portable manures as the standard. One or two illustrations map be given of the applicability of the latter mode of reckoning. In the summer of 1863 Haron Liebig adopting as the basis of his calculations an analysis of the Dorset Square sewage by Mr. Way which showed nearly 18grains of ammonia per gallon estimated that (provided the quantity of phosphates which he considered requisite to render the whole of the ammonia available were employed with the sewage) tiie con- stituents in 1 ton of sewage of that composition would be worth AND UTILIZATION OF TOWN SEWAGE.about 4d. Now according to oiir mode of estimate stated above 18 grains of ammonia per gallon would indicate a value of 18 farthings or 44d. for the total constituents in 1 ton of the sewage. In January 1865 Baron Liebig assumed the average sewage of the Metropolis to contain only 7.2 (instead of IS) grains of ammonia. per gallon; and he estimated the value of the con- stituents in 1ton of' such sewage to be rather over 1gd. Our estimate would also give rather over 7 farthings or 12d. Lastly on this point in 1857 Messrs.Hofmann and Witt cwhded from their investigations that the average dry weather sewage of the Metropolis contained about 8.2 grains of ammonia per gallon; and calculating the value of the sewage according to the amount of ammonia organic matter phosphoric acid and potassa they estimated that of the total constituents in 1 ton of such sewage to be about 2*lld It is clear that giving a value of' id. to the total constituents per ton of sewage for each grain of ammonia per gallon would yield almost identically the same result. It is obvious therefore that in this part of the discussion we may for all practical purposes safely disregard everything but the amount of ammonia contained in the sewage and that by so doing the consideration of the subject will be greatly simplified.It mill be seen too that in adopting this course we do not in any way ignore or undervalue the importance of the associated con- stituents but on the contrary accord to them the same value as Barm Liebig Messrs. Hofmann and Witt and others have done by a much more elaborate process of calculation. Numerous analyses have been made from time to time of samples of the Metropolitan and other sewage; and sometimes very important theoretical conclusions and even propositions for the investment of enormous amounts of capital in utilization schemes and anticipations of enormous profits from their adoption have been based upon the results of a single analysis Such however is the variation in the dilution of the sewage of any one locality at differeut times that it is quite impossible to draw any safe conclu- sions from the results of analysis without carefully taking into consideration the circumstances affecting the dilution at the time of sampling.This is strikingly illustrated by the results given in Table I. in which are recorded the grains of ammonia per gallon as determined by various experimenters in samples of the Metro- politan sewage taken at different times and places and also the estimated value of the total constituents in one ton of the sewage 90 LAWES AND GILBERT ON THE COMPOSTTION VALUE reckoned according to the number of grains of ammonia per gallon as above referred to. TABLE I. Gyrains of Ammonia per gallon in difeyent samples of Metropolitan Xewage and estimated value oj' Cowtituents in one ton.Time of Ammoni Authority. Name of Sewer. Sampling Gallon. Per -__. Urains. Barrett's Court .......... W 41 '28 Way.. ............ Dorset Square .......... =aY 17.96 Noon 5 -15 The Fleet ............ Midnight 8 -50 Noon 6 -69 London Bridge.. ...... Midnight; 8 910 Noon 10.03 Dowgate Dock ........ Midnight 3 a43 Noon 8 -13 Iron Gate ............ Midnight 6 *20 Noon Paul's Wharf.. ........ { Midnight 12 -01 3 *13 5 *35 Whitefriar's Dock.. ....{ Noon Letheby .......... Midnight 3 -41 Noon Cusbm Home West .. { Midnight 6 -25 8 -17 Noon Custom House East.. .. { Midnight '7.28 15 *01 Noon 7 *69 Hambro' Wharf.. ...... I Midnight 5 *69 Noon 6 95 Wool Quay ..........{ Midnight 5 so0 Noon 10 so2 Tower Dock ..........{ Midnight 7.15 ......... '7 *24 Hofmann & Witt .. Savoy Street ............ 24 hours 8 *21 The results given at the head of the table on the authority of Mr. Way are those of probably the first analyses made of the Metropolitan sewage and it is only fair to say that at the time he published them he expressly stated that although they showed that there was great manurial value in sewage yet they could not be taken as in any way afTording a measure of that value. It was however upon the analysis of the sample of the Dorset Square sewage showing nearly 18 grains of ammonia per gallon that Baron Liebig based his calculations as to the value of the Metropolitan AND UTILIZATION OF TOWN SEWAGE.sewage in 1863 j and the advocates of particular sewage schemes and even members of P.zrlizmentary Committees have sought to fouiid much upon the results of those analyses. From the varying circumstances under which the samples analysed by Dr. Letheby were taken as indicated in the table it is obvious that the results though very valuable in that respect must be considered rather as illustrations of the variation in composition of the Metropolitas sewage at different times and places and as showing the danger of founding important practical conclusions upon the results of the analysis of an individual &ample than as affording direct evidence as to the average composition of the Metropolitan sewage.The sample analysed by Messrs. Hofmaun and Witt was B mixture of equal portions taken every hour during twenty-four hours of dry weather and there is no doubt that that sample had better claims to be taken as representing the average dry weather sewage of the Metropolis than any other that had up to that time been collected and examined. It was upon the analysis of this sample that Messrs. Hofmann and Witt calculating the value of the ammonia organic matter phosphoric acid and potassa which it contained estimated that the constituents in one ton of such dry weather sewage would be worth rather over 2d. and according to the information supplied to them for the purpose of their calculations the quantity of sewage exclusive of rainfall would be about 158,000,000 tons per annuen or scarcely three- fifths as much as that assumed in the estimates of Baron Liebig and Mr.Thomas Ellis as the total sewage namely 266,000,000 tons. Yet Messrs. Hofmann and Witt’s estimate of a little over 2d. for the value of the constituents in one ton of the normal dry weather sewage was taken by Mr. Ellis in his application for the concession of the Metropolitan sewage as applying to the whole amount of dilute sewage (inclusive of rainfall and subsoil water) which he estimated would be available for utilization (266,000,000 tons) and his calculations of profit to his Company and to the ratepayers were based upon this erroneous assumption. To conclude in reference to the results recorded in Table I.attention may be called to the fact that the different samples show a variation of from about 3 to more than 41 grains of ammonia per gallon representing approximately a difference of from about gd. to about 10id. for the estimated value of the total constituents in one ton of the sewage. 92 LAWES AND GILBERT ON THE COMPOSITION VALUE That the results of an analysis of a sample of sewage of any locality taken without careful reference to the circumstances of its dilution are not only entirely inadequate as the basis of general conclusions but may even be utterly misleading is even more strikingly illustrated by the results next to be considered which were obtained in the course of an investigation undertaken by the late Royal Sewage Commission.Three members of the Commission the late Mr. Henry Austin C.E. Mr. Way and one of the authors (J. B. Lawes) were appointed a subcommittee to undertake an investigation on the utilization of sewage. The agricultural experiments were conducted at Rugby and their management and the selection collection and preparation of samples for analysis devolved upon the authors the analyses being made in the laboratory of Mr. T7C'ay. The inquiry extended over a period of between three and four years and involved the application of different quantities of sewage to meadow-grass and some other crops ; the determina- tion of the amounts of produce obtained; the feeding of fattening oxen and milking cows on the unsewaged arid the sewaged grass; and the sampling and more or less complete analysis of the soil of the sewage of the drainage-water from the irrigated land of the unsewaged and the sewaged grass of the milk yielded by the cows fed upon it &c.&c. It is proposed to embody in the sequel a brief abstract statement of some of the more importaut facts and conclusions brought out by the experimental inquiry above referred to and the reader is referred fur all fuller details to the Reports of the Commission.* The mode of collecting samples of the Rugby sewage for analysis was to take ahout a quart (from a gauge-tank holding between 3 and 4 tons through which the sewage flowed bcfore passing on to the land) at intervals of about two hours for several days tugether well mix the quantity so accumulated acd take a sample of the mixture for analysis.93 sueh mixed samples were collected and analysed the period of collection extending over 31 moxths from April 1861 to October 1863 inclusive. Table 11. shows the highest the lowest and the average amounts of ammonia and total solid matter wliich the analyses of these numerous mixed samples indicated. * Second and Third Reports of the Commission appointed to inquire into the best mode of Distributing the Sewage of Towns and applying it to beneficial and profitable uses. 1862 and 1865. AND UTILIZATION OP TOWN SEWAGE. 83 TABLE IT. Slwwing the highest lowest,and average amounts of Ammonia and tot& So;lid Math in raked samples of Rugby Sewage at diferent times.Ammonia. Potal Solid Matter. Grains lba. Grains Ibs. Per per lOQO Per xr 1000 Gallon. Tons. Gallon. T0I.U. -7 1861 { Highest.. .................. Lowest .................... Mean Df 24 analyses ........ 15 *64 2 -99 6 -39 500 -5 95 -7 204 -5 216 -5 37 *6 75 -1 6928 1203 2405 i1861-2 Highest.. .................. Lowest .................... Mean of 34 analyses ........ -11-38 2 -55 5 -95 364.2 81 *6 190 -4 129 *3 50 -5 ao .3 4138 1616 2570 1862-3 Highest. ................... Lowest .................... 12 *81 3.14 409-9 100 -5 269.9 62 *2 8637 1989 Mean of 35 analyses ........ 7-08 226 *5 103 *2 3302 Thus although each sample andysed was a mixture of samples taken over several days together as above described there was a variation among the 93 samples of from 2+ to 15+ grains of ammonia and from 374 to 270 grains of total solid matter per gallon; or of from Sli to 50031bs.of ammonia and from 1203 to 8,6371bs. of total solid matter per 1,000 tons of sewage. Reckoned according to the number of grains of ammonia per gallon the estimated value of the total constituents in 1ton of sewage varied from about Sd. to nearly 4d. Notwithstanding the very great differences in the composition of the Rugby sewage a$ different times much greater indeed khan could have been expected considering the circumstances of the sampling it is still believed that the mean of so many deter- minations may be taken as indicating at any rate approximately the average eomposition of the Rugby sewage over the period to which they refer.The probability of this will be seen on a consideration of the average results for each of the three sea- sons and for $he total period of 31 monthsof collection given in Table 111. ........ ...... s!uomm~ .... uo!soadsnsnopnp UIUI I I Z9.9f 82.01 PI. 98 Zll.82 AND UTILIZATION OF TOWN SEWAGE. It is seen that the mean result of the analyses of 24 samples collected from April to October inclusive 1861 indicates 6.39 grains of ammonia per gallon; that of 34 samples collected from November 2861 to October 1862 inclusive 5-95 grains and that of 35 samples collected from November 1862 to October 1863 inclusive 7.08 grains. This difference in the average con- centration of the sewage of the different seasons is perfectly consistent with the difference in the character of the seasons them- selves.Thus the season of 1861-2was much the wettest and its sewage was accordingly the most dilute; the season of 1862-3 was much the driest indeed extremely dry arid its sewage was the strongest; and the season of 1861 being intermediate in this respect its sewage was of intermediate strength. Looking to the average result of the 93 analyses it will be observed that the sewage contained about 874 grains per gallon of total solid matter of which about two-thirds was inorganic and one-third organic. About half of the total solid matter was in ;.Suspension and half irr solution of the half in suspension about four-sevenths was inorganic and three-sevenths organic and of the half in solution about four-fifths inorganic and one-fifth organic.Lastly of the nitrogen reckoned as ammonia about one-fourth mas in suspension and three-fourths in solution. The mean of the 93 analyses shows about 6$ grains of ammo-nia per gallon indicating a value of about I3d for the total constituents in 1 ton of the sewage. But taking into considera- tion the fact that the samples were not collected at exactly equal intervals throughout the total period it is concluded that by taking the mean result for each of the 31 months separately and then the mean of the 31 means so obtained the result will more nearly represent thereal average composition of the sewage of the whole period than will the direct mean of the 93 analyses; and the calculated average so obtained indicates about 7 instead of only 64 grains of ammonia per gallon.From all the informqtion at command as to the population con- tributing to the sewers the water-supply the rainfall and the drainage area it was concluded that taking the average of seasons there are about 60 tons of sewage per head of the population of Rugby per anrium ;but that as the period of the experiments was drier than usual the amount probably then reached to only about 55 or 56 tons. Now if we reckon C;& grains of ammonia per gallon and 60 96 LAWES AND GILBERT QN THE COMPOSITIOR VALUE tons of sewage per bead per annum it would result that 124Ibs. of ammonia were contributed annually for each average individual of the mixed population of both sexes and all ages; or if we reckon 7 grains of ammonia per gallon and 56 tons of sewage per head per annum we equaIly arrive at the amount of 129lbs.of ammonia per head per annum; and from a careful consideration of the Rugby results it was concIuded at the time the Report was issued that this probably very nearly represented the actual truth. Having then by means of the results of a great many analyses of sewage and a consideration of the amount of sewage contri- buted by each average individual of the population estimated that for each such average individual there would be about 12; lbs. of ammonia contributed to the sewer-water let us next see what TABLE IV. Amount of Nitrogen reckoned as Ammonia and estimated value of totaE Conetittaents in Human Voidings,per head per unnum.Value of Conatituents. Adult Males ; Hofmann and Witt. 1bS. 8. d. Urine .................... 15 -8 10 0% 2.3 Faeces .................... ---1 s+ Total ............ 18.1 11 9) Urine .................... 11 -32 73 Faxes .................... 1 -64 1 22 Total ............ 12.96 8 52 Average both sexes and all ages ;Lawes and Gilbert. Food.. ...... 12 *2 .... 12 -6 Voidings .... 12 -7 Mean .... 12.5 AND UTILIZhTPON OF TOWN SEWAGE result is arrived at by t.he other method of comptation which has been referred to namely by the calculation of the amounts of faxes and urine or of the various constituents of these recorded as voided by persons of different sexes and ages.Table IV. very concisely summarises the information available on this subject SO far as it is necessary for our present purpose. To check their estimates founded on the analysis of the 24-hours’ mixed sample of the Savoy Street sewage Messrs. Hofmann and Witt took the amount of urine estimated to be daily voided by an adult and the amount of faxes recorded as voided on the average per head of the body-guard of the Grand Duke of Hesse Darmstadt (but allowing as they said a little more for John ‘I Bull”) and applying the results of Berzelius’ analysis of urine and those of the analyses of Way Liebig and Vesarg of faxes they calculated the amount of ammonia and other constituents daily voided by such persons.Accorrling to their data the amount of ammoriia annually voided by an adult male was in urine 15.8 ir? faxes 2.3 total 18.1lbs. ;and the estimated money value of the constituents was in urine 10s. Oid. in faxes 1s. 8#d. total 11s. 94d. The result so obtained for adult males they take as applicable to each individual of a mixed population of both sexes and all ages assliming that other matters reaching the sewers would probably make up the difference. There can belittle doubt that this was making far too liberal an allowance for other than human excretal matters contributing to the value of the sewage. Some years later in 1863 Dr. Thudichum from much more comprehensive data gave for the urine alone of an adult male 15.9 lbs. of ammonia and 10s.34d. of value; amounts which it will be seen are almost identical with those of Messrs. Hofmann and Witt. But Dr. Thudichum instead of directly applying the results obtained for an adult male to each average individual of a mixed population considered that tcvo adult males would approximately represent 2.8 such average persons. Now if me take the mean of the estimates of Messrs. Hofmann and Witt and Dr. Thudi-churn with regard to the urine and those of Messrs. Hofmann and Witt with regard to the faxes of an adult male and reduce both in the proportion of from 2-8 to 2 according to Dr. Thudi-chum’s basis of calculation we shall provided the estimates of these authorities be correct arrive at amounts approximately applicable to a11 averzge individual of a mixed population of both 98 LAWES AXD GILBERT ON THE COMPOSITION VALUE.sexes and all ages. By this process as the Table shows we have iiearly 13lbs. of ammonia and nearly 8s. 6d. of value to represent the mixed voidings of such an average individual. In 1854 the authors basing their estimates on very compre-hensive data relating both to the amounts of constituents con-sumed in the food arid voided in the urine arid fieces of persons of different ages arid both sexes concluded that probably about 10 Ibs. of ammonia and total constituents of the estimated manurial value of about 6s. 8d. were annually contributed to sewage per individual of a mixed town population. More recently for the purposes of the Report of the Koyal Sewage Commission all the estimates relating to the constituents voided were carefully revised bringing into the calculations such fuither information as was then at command ;* and the results so obtained are recorded in the Table (IV).The amount of nitrogen estimated to he amudly consumed in the food of an average individual was deduced from the calculatioii of 86 dietaries arranged in 15 classes according to sex age activit7 of mode of lifc and other circumstances and corresponded to about 12.2 lbs. of ammonia; from which of course a deduc- tion has to be made for the nitrogen retained in the body and for loss in various ways. When the calculation was based upon deter-minations or coniputations of the amounts of iii trogen or ammonia-yielding matters voided by persons of differerid sexes and ages the residt arrived at was 12.6 lbs.of ammonia; and when upon tlie rccorded amounts of fresh wine ahd fzces voided and the average composition of these the amount indicated was 12.7 111s. of ammonia per head per annum. A careful consideration however of the circumstances of the majority of the mses contributing to the averages among those divisions of the population in relation to which the evidence is the most plentiful and of the relative character of the results where it is the most deficient led to the conclusion that the estimate of 12.6,or 18*71bs.for the amount * For nearly the whole if not the whole of tlie data upon which the new estimates are based 6ee ” On the Sewage of London,” by J. B. Lawes F.R.S.Jairnal 0-f the Society of Arts March 9 1855; “The Composition of the Urine in Health and Djs-ease,” by E. A. Parkes M.D. 1560; “On an Improved Mode of collecting Excre- mentitious Matter with a view to its Application to the benefit d Agriculture &c ,” by J. L. W. Thudichum M.D. F.C.S. Journal of the Society of Arts May 15 1863; and @‘Onthe Elimination of Urea and Urinary Water in relation to the period of the Day Season Exertion Food &c. &c.,” by lidward Smith M.D. LL.B. F.R.S. Pliilosophical Transactions vol. cli p. 747. AND UTILIZATION OF TOWN SEWAGE. of ammonia voided annually by an average individual of a mixed population was in all probability too high. Reviewing the whole of the evidence both that relating to the composition and the amount of the Rugby sewage and that relating to the amount of constituents voided by an average indi- vidual it was concluded that the amount of' ammonia annually contributed to the sewer-water by an average person of a mixed population was pretty certaiiily more than 10 lbs.as formerly assumed but probably less than 12lbs. ; and making allowance for the fractional part of the excretal matters of horses cows dogs and other animals of the refuse of slaughter-houses of soot and of other refuse matters that may reach the sewers it was concluded that still not more than 124lbs. of ammonia would be contributed annually to the sewers from all sources per head of mixed town population. This would indicate an estimated value of 8s.4d. per annum for the total constituents in the sewage for each average individual. It was admitted however to be a great desideratum that when the Main Drainage of the Metropolis came to be completed and the works to be in full operation competent persons should he appointed to superintend the gauging sampling and analysis of the sewage with a view to providing data which might serve to determine satisfactorily and conclusively the approximate amount and average composition of the Metropolitan sewage as it will have to be dealt with in any plan of utilization and also the relation of population to the composition of sewage generally. Since the publication of the Report of the Comiaission in Xarch 1865,numerous gaugings and samplings of the sewage of the mid- and high-level sewers North of the Thames have been undertaken and many samples have been analysed by Mr.Way The results of this inquiry have not yet been published; but from information kindly communicated by Mr. Way we are enabled to state their general bearing so far upon the point now under consideration. From these new results it appears very probable that the amount of dry weather sewage averages only about two-thirds as much per head of the population as that generally supposed before and assumed both in the inquiries of Messrs. Ho fm a nn and TIT;t t and in the Report of the Sewage Commission; but the average amount of ammonia per gallon now found by Mr. Way in the dry weather sewage very uearlg approaches that arrived at by Messrs.Hofmann and Witt. Both Mr. War and Mr. Cresy 100 LAWES AND GTLBEILT ON TEE COMPOSITION VALUE frankIy admit however in accordance with common experience the further a suhject is investigated that there are still many open questions the settlement of which may materially aEect the proper interpretation of the new gaugings. Assuming them to indicate the result at present supposed arid above stated it follows that the total amount of ammonia yielded by a given popnlation wiII be onry about two-thirds as much as that estimated by Messrrs. Hofmann and Witt on applying the results of their analysis to the higher estimated amount of the dry weather sewage. It further follows fiDm the same evidence that the amount of ammonia annually contributed to the sewage from all sources per head of a mixed population is more nearly 10 lbs.as formerly coticludecl by the authors than 12* lbs. as more recently estimated ;and if this result should be confirmed their former estimate of 6s. 8d. will more nearly represent the calculated annual value of the total constituents yielded per head of the population than the more recent one of 8s. 4d. It would then have to be crincluded as indeed is not improbably the case that in the calculations based on the mean composition and the estimated total amonnt of the Rugby sewage the latter had been taken at too high a figure too large a proportion of the rainfall having been asslimed to reach the sewers; and that in the estimates founded on the recorded amounts of constitiients voided the incompleteness of the records as already pointed out had as was supposed led to too high an estimate.We have then from 10 to 12i lbs. of ammonia and all esti- mated value of from 6s. 8d. to 89. 4d. for the total. manurial con-stituents contributed to sewage by each average individual of a mixed town population. Adopting these amounts the questions arise-What will be the amount of ammonia aid what the esti- mated value of the constituents in a given amount of sewage at different dilutions? Thesc points are illustrated in Table V. AND UTILIZATION OF TOWN SEWAGE. 101 TABLE V. Ammonia per galhn and estimated value of tdal Constituents in oite ton of Sewuge at ilifereent dilutions. If 12+lbs.Ammonia If 10 lbs. Ammonia Dilutions supposed. per head per annum per head per annum from all sources. from all Bources. I I Estimated Per head Per head per Ammonia Estimated Ammonia value value per annum. per gallon. per ton. per gallon. per ton. Tons. Grains. Pence. Grains. Pence. 40 9 -77 2 *44 '7 -81 2 '00 50 1 7 -81 1 *95 6 -25 1 *60 60 6 *51 1*67 5 -21 1 -33 70 5 *58 1-43 4 -46 1-14 80 4 -88 1.25 3 *91 1 *oo 90 4 *34 1 -11 3 *47 0 -8Q 100 3.91 1 -00 3 -13 0 -80 200 1 *95 0 *50 1 *56 0 -40 According to the information supplied to Messrs. Hofmann and Witt the dry weather sewage of the Metropolis amounted to between 36 and 37 galloiis per head per day = about 60 tons per head per annum. Their analysis showed 8.2grains of ammonia per gallon equivalent to about 153 lbs.of ammonia per head per annum; and they reckoned the total constituents in 1 ton of such sewage to be worth 2*lld. But Table V shows that with a dilution of 60 tons and with 125 lhs. of ammonia per head per annurn there would be only 6.5 grahs of ammonia per gallon and total constituents in 1 ton of sewage worth only 13d.; and that with only 10 Ibs. of ammonia per head per annum there would be only 5.2 grains per gallon and constituents worth only l+d. in 1 ton of the sewage. If however we take the dry weather sewage as indicated by the recent gaugings as more nearly 24 gallons per head per day = a rate of 40tons per head per annum we have then with 12+ lbs. of ammonia per head per annum 9.77 grains per gallon and 2*44d.worth of constituents per ton ; or taking 10 Ibs. of ammonia per head per annum we have 7.8grains per gallon and constituents in 1 ton of an estimated value of nearly 2d. Now Mr. Way's conclusion is that the mid- and high-level dry weather sewage North of the Thames averages scarcely but nearly 8 grains of VOL. XIX. I 102 LAWEB AND GILBERT ON THE COMPOSITION VALUE ammonia per gallon or almost exactly the amount last mentioned; and as Messrs. H ofm an n and Wit t ’s analysis shows 8.2 grains it will be seen that both estimcttes taken in corsnexion with the amended one as to the daily amount per head of the dry weather sewage go to confirm the assumption that the amount of ammonia contributed to the sewage from all sources is much more nearly 10 than 12+ lbs.per head per annum. Whatever may eventually prove to be the average dilution of the dry weather Metropolitan sewage the actual amount of fluid varies immensely from time to time according to rainfall and other circumstances. When it exceeds a certain amount as in the case of continuous rains or storms a portion will pass at once into the ‘l’hames ; and according to Mr. B az alget t e’ s figures it appears that this will happen when the volume is such as if con- tinuous would represent something over 200 tons of fluid per head per annum. But so far as information at present at com- mand enables us to judge it is probable that the amount inclu- sive of rainfall and subsoil water that will be available for utilization will be somewhere about 80 and will pretty certainly not exceed 100 tons per head per annum; that is about twice or not more than twice and a half as much as the most recently estimated dry weather flow.Of course to result in anything like such averages the dilution would sometimes be at a rate very much greater than those amounts mould indicate. But it may be observed by way of illustration that with lZ+ lbs. of ammonia per head per annum and an average of 80 tons of sewage it would average less than 5 grains of ammonia per gallon and only 1-25d.worth of constituents in 1ton ; or reckoning an average dilution of 100 tom it would average less than 4 grains of am-monia per gallon and only Id. of value of constituents in I ton. In like manner reckoning only 10 lhs.of ammonia per head per annum a dilution of 80 tons would show less than 4 grains and of 100 tons little over 3 grains of ammonia per gallon and an amount of constitiients in 1 ton worth only Id. and 0Bd. respec-tively. In comparison with the figures just given it may be stated that both Baron Liebig and Mr. Thomas Ellis (one of the appli- cants for the concession of the Metropolitan sewage) assume its total amount at 266,000,000 tons per annum which with 3,000,000 population represents nearly 90 tons per head per annum and with this dilution the former estimates the sewage AND UTILIZATION OF TOWN SEWAGE. to contain an average of 7.2 and the latter 8.2grains of ammonia per gallon; the latter as already stated applying the estimate of Messrs.Hofmann and Witt for the dry weather sewage to the total estimated amount of available sewage inclusive of rainfall. It is sufficiently obvious that however variable the dilution of the constituents iu town sewage is at any rate very great and that in any scheme for the utilization of sewage large quantities will have to be dealt with. It will be useful therefore by way of illustration and as a means of conveying a more definite idea of the extent of this dilution to show the relation of a given amount -say 1,000 tons-of sewage of certain assumed dilutions both to population and to some well-known portable manure such as Peruvian guano This is done in Table VI which shows the amount of gunno which would supply as much nitrogen reckoned as ammonia as 1,000 tons of sewage of diEerent dilutions also the number of tons of sewage which would be equal in this respect to 1 ton of guano and both on the alternative assump- tions of 12+lbs.and 10lbs. of ammonia per head per annum. The assumed dilutions are 40 50 and 60 tons per head per annum which may be taken to cover the minimum and maximum esti- mated rates of flow for the dry weather sewage of the Metropolis; 80 and 100 tons which may be taken to represent the range for the average total available sewage,inclusiveof rainfall and subsoil water and 200 tons the probable frequent dilution in wet weather. TABLE VI. Relation of Sewage to Peruvian Guano in amount of Nitrogen reckoned aa Ammonia. If 12i lbs.Ammonia If 10 lhs. Ammonia, per head per annum per head per annum If Sewage Contributing from all sources. from all sources. per head 1,000 tons per annum. Sewage. 1,000 tons 1ton 1,000 tons 1ton 1 Sewage Guano Sewage Guano = Guano. = Sewage. = Guano. = Sewage. Tons. Persons. Cwts. Tons. cwts. Tons. 40 25 164 1220 13 1525 50 20 13 1525 lo* 1900 60 163 11 1830 2290 80 124 8% 2940 64 3050 100 10 6Q 3050 54 3810 200 5 34 6100 28 7620 ~-1Person = Guano. 8 cwt. 4 cwt. I J2 104 LAWES AND GILBERT ON THE COMPOSITION VALUE Thus with 12+ lbs. of ammonia md the minimum estimated dilution of the dry weather sewage at a rate of 40 tons per head per annum 1,000 tons of such sewage would only contain nitrogen reckoned as ammonia equal to that in about l6$ cwts.of Peruvian guano or to that in only 13 cwts. if the amount of ammonia per head per annum be reckoned at only 10 lbs. In other words in the former case it would require 1,220,and in the latter 1,525 tons of sewage to supply the ammonia (or nitrogen reckoned as ammonia) of 1ton of guano. In like manner taking 80 tons of sewage per head per annum as a mininium estimate for the average sewage inclusive of rainfall with 12+ lbs. of ammonia per head per annum 1,000 tons would represent the nitrogen of 84-cmts. and with 10 lbs. 6+ CW~S. of Peruvian guano; or reckoning 12* lbs. of ammonia per head per annum 1 ton of Peruvian guano would represent 2,440 tons and reckoning 10 lbs. it would represent 3,050 tons.The table also shows that reckoning 124 lbs. of ammonia per head per annum the sewage of an average individual would annually represent in nitrogen 9 cwt. or reckoning only 10 lbs. per head per annum only Q cwt. Peruvian guano per head per annum. Crops to which Sewage is most applicable. Hitherto on grounds shown to be fully justified we have for simplicity of illustration confined attention to the amount of nitrogen or ammonia in sewage as the measure or indication of its composition and of the theoretical manurial value of its total solid constituents. It is however obviously of interest to consider whether or not the mineral or incombustible constituents of sewage exist in it in sufficient proportion to the ammonia or nitrogen for the requirements of the crops to be grown; and as the phosphoric acid and potassa (the one or the other or both according to circumstances) are perhaps the mineral con- stituents most likely to be deficient relatively to the nitrogen their proportion to the latter in sewage and invarious crops may appropriately be referred to in illustration of the point.Table VII shows the proportion of phosphoric acid and potassa to 100 of nitrogen in sewage according to the mean of ten analyses of the Rugby sewage in which the phosphoric acid and the potassa as well as the ammonia were determined. It also shows what AND UTILIZATZON OF TOWN SEWAGE. may be taken as approximately representing the average propor- tion of phosphoric acid and potassa to nitrogen in various crops.TABLEVII. Amourat of Phosphoric Acid and Potassn to 100 Nitrogen in Sewage and in variow Phosphoric Acid. Potassa. Rugby Sewage .... 27 42 In Corn In Straw [n Total [nCorn In Straw In Total Roots &c. Leaves &c Produce loots,&c. Leaves &c Produce. I Meadow-Hay ...... Clover-Hay ........ Wheat.. .......... .. .. 48 .. .. 42 27 23 46 .. a. 28 .. .. 108 100 52 57 Barley ............ Oats. ............. 40 28 34 37 38 30 34 25 126 155 60 65 IBeans ............ 25 46 30 32 123 50 Mangolds ........ Swedes .......... 17 27 16 .. 21 .. 100 82 44 .. 63 .. Common Turnips .. Potatoes .......... 28 42 18 .. 26 I. 160 123 71 .. 117 .. It is obvious that since the phosphoric acid of sewage like the nitrogen will be derived almost exclusively from excretal matters and food-refuse its proportion to the nitrogen will within com-paratively narrow limits be tolerably uniform ; the amount of potassa on the other hand will vary very much according to locality and be considerably greater where the streets or roads are constructed of potassic minerals than elsewhere.The table shows that according to the analyses referred to the Rugby sewage contained 27 parts of phosphoric acid and 42 parts of potassa for 100 of nitrogen. It also shows that on the average meadow hay contains almost exactly the same proportion of phosphoric acid to nitrogen as the sewage but a much greater proportion of potassa than the latter.' In the cereal grains the proportion of phosphoric acid to * According to Baron Liebig's estimates hay contains 51 parts of phosphoric acid to 100 of nitrogen ;but having collated and averaged the results of numerous independent observers we can see nothing to lead to the adoption of such a 6gnre ; whilst direct determinations in a number of samples of each showed in the Rugby sewaged grass 25 and in the unsewaged 32 parts.106 UWES AND GILBERT ON THE COMPOSITION VALUE nitrogen is on the other hand higher than in the sewage; whilst in most of the other crops enumerated it is much about the same. Of potassa the proportion is lower in the cereal grains (the only part of the crop which is as a rule sold off the land) than in the sewage though in the other crops it is generally higher. But there are various circumstances the adequate discussion of which would occupy more space than it mould be appropriate to devote to their consideration here which render it quite in- admissible to draw direct practical conclusions as to the applica- bility of sewage to different crops from what may appear at first sight the obvious indications of the figures in the table.Never-theless a careful consideration of the subject leads to the conclu- sion that if sewage alone were applied constantly to meadow land potassa would be more likely to become deficient than phosphoric acid; but that if it were applied to the ordinary crops of rotation phosphoric acid would be more likely to become deficient than potassa. Still granting it to be clearly shown that with this or that description of soil or management town-sewage was in pro-portion to its nitrogen deficient in this or that constituent for the production of this or that crop or crops generally it would by no means follow that it was an inappropriate manure on that account ; for any defect in composition whether in regard to phosphoric acid potassa or any other constituent could be easily cornpen- sated from other sources.Indeed independently of what we know of the sonrces of the constituents of tiewage and can judge therefrom of their appro- priateness as manure for dizerent crops there is nothing in the results of the analysis of the solid matter of sewage from which we should be justified in concluding that it ia not applicable as manure to crops generally.On the contrary a dry and portable manure having the composition of the solid matter of tomn-sewage would undoubtedly be generally applicable both to corn and other rotation crops and to grass; and its constituents could then fairly be valued by the same scale as other concentrated manures in the market. But the great dilution of town sewage its large daily supply at all seasons and its greater amount in wet weather when the land can least bear or least requires more water render it extremely inappropriate for application on a comprehensive scale to arable laud for the growth of corn and other ordinary rotation crops. AND UTILIZATION OF TOWN SEWAGE. But apart from these difficulties if sewage can only be distributed in small quantities over large areas at such a cost to the farmer as has yet been proposed it is indeed vain to hope that any large proportion of the manurial constituents derived from the con-sumption of human food in our towns can be redistributed over the area from which they came; for such is the limit set by climate to the amount of manure and of water applicable for crops that have to ripen their seed that for corn more especially only coinparatively small quantities per acre could be employed and hence were sewage systematically applied for their growth the area of utilization must necessarily be very large.On this point it may be stated that Mr. Rawlinson one of the members of the Royal Sewage Commission has given it as his opinion that it would cost more to distribute 500 tons of sewage per acre by means of pipes hydrants and hose and jet as would be requisite in the case of application to arable land and crops generally than to apply 5,000 tons per acre by means of open runs as in the case of its application to grass.From these considerations it will be obvious that that which may be called the theoretical value of sewage reckoned according to the constituents it contains is not necessarily its practical or ayailable value when used in its highly diluted condition. Tt will be also obvious that in that condition it is the most appropriate for grass for which it can be employed at all seamns and in com- paratively large quantities on a limited area and that it is the least appropriate for crops which have to ripen.The question arises-what is the practical or realizable value of the constituents of sewage when they are utilized in the condition of dilution in which they exist in that fluid? This point will be illustrated by reference both to the results of direct experiments and to the experience of practical men who have utilized sewage with a view to profit. Results of direct Experiment on the UtiZization of Sewage. At Rugby two fields of meadow land were experimented upon ; in each one plot was left without sewage one received sewage at the rate of 3,000 tons one at the rate of 6,000 tons and one at the rate of 9,000 tons per acre per aunurn. The experiments were so conducted through three consecutive seasons and Table VIII summarizes the results obtained.108 LAWES AND GILBERT ON THE OOMPOSITION VALUE TABLEVIII. Quantitier of Sewage applied and of &eat cs'rass obtain& per acre per annurn in Expeclci-mnts d e at Rugby. Seasom 1861 1862 and 1863. Plot 2. Plot 3. Plot 4. 1 1 seasons. U::i:;ed. 3,000 Tom 6,000 Tons 9,000 Tons Sewage. Sewage. Sewage. Grass obtained. Pive-Acre Field. Tons.cwts. qrs. lbs< Tons.cwts. qrs. Ibs. 9 63 5 32 16 3 8 a 3110 32 9 2 22 1863 4 18 3 13 I 37 02 6 ~~~ I_-Average.. .. 7 9 1 9 21 13 1 12 32 3 1 0 34 2 1 12 Ten-Acre Field. 8 18 0 15 1863 8 0319 Average.. .. 111-3010122 173 1128 9313131 1318 Averages :-the three years and both Fields. 1 1861 2,and3 9 6 0 24 22 6 2 'I I30 6 2 6 I32 12 0 15 The five-acre field was much flatter than the other ; its soil and subsoil were much more porous; the mechanical and chemical examination of samples taken to the depth of 9 inches showed its soil to be much more stony to retain much less water under equal external conditions to contain much less organic matter much less nitrogen much less clay and much more sand than that of the ten-acre field.It was in fact considerably inferior in natural quality and yielded accordingly considerably less produce without manure. Notwithstanding this it will be seen that it gave upon the whole more total produce per acre under the influence of sewage than did the naturally better soil of the ten- acre field; and it will be shown further on that the sewage was in its case both more completely utilized and more completely purified.AND UTILIZATION OF TOWN BEWAGE. It would be inappropriate to discuss in detail here the influence of season and other circumstances upon the produce of the different years or the respective plots. It will be sufficient to call attention to the general character of the results and to the practical con-clusions to which they seem to lead. By the application of sewage a supply of green food was obtained much earlier and much later in the season and the total quantity per acre was increased several fold. There was generally though not invariably the more produce the greater the amount of sewage applied the exceptions being in the wet and cold season of 1862. In the other seasons and in both fields there was an increase of produce with each increase in the amount of sewage applied ;and the largest amounts of produce obtained at all were in both fields in the third season of application and on the plots which had received the largest amounts of sewage.Still it is important to remark that the amounts of increase of produce for a given amount of sewage applied were the less where the larger quantities were employed. Experience abundantly shows indeed that if the only object were to get the largest possible amounts of' produce per acre as much as 30,000 40,000 or even 50,000 tons of sewage might frequently be applied per acre with advantage; but under such conditions the sewage would be very inadequately both utilized and purified and a minimum amount of increase would be obtained for a given amount of sewage applied.Looking however both to urban and to rural interests and to purification as well as utilization much more moderate applications than such as are required to yield the greatest amount of produce per acre must be had recourse to By way of practical suggestion on this point it may be stated that on consideration of the circum- stances under which the amounts of produce recorded in the Table were obtained it is concluded that with an application of about 5,000 tons of average sewage per acre per annum applied as it must be pretty evenly throughout the year there might be expected taking the average of soils and seasons an average of about 30 tons of grass.Assuming such a produce and allowing 24 per acre for rent or natural yield the grass would if sold for 10s. per ton give a gross return of 0.53d. per ton of sewage employed if for 12s. 6d. per ton 0*7d. and if for 15s. per ton 0*9d. From these amounts there would of course have to be deducted the cost of main distribution and application of the sewage other expenses of the crop and the farmer's profit before 110 LAWES AND QILBEBT ON THE COIHPOSITION VALUE anything was available as payment to the town for the manurial matters. In comparison with the result here assumed it may be observed that in the neighbourhood of Croydon where about 250 acres are laid down for sewage irrigation and where there are probably more than 6,000 tons of sewage annually available for each acre from 25 to 30 tons of meadow grass selling for from 220to g25 are obtaiiied per acre per annum; and after deducting as before $4 for rent the gross return per ton of sewage employed is from 0.6d.to 0.8d. With a somewhat similar application to Italian rye-grass 30 to 35 tons selling for from 225 to 230 are obtained yielding after deduction for rent or natural produce from 0.8d. to Id. per toil of sewage employed. It will be observed that in these cases the selling price of the grass is 16s. or 17s. per ton ; but it is obvious that if sewage were extensively employed for the production of grass its present price could not be maintained. A marked effect of liberal sewage irrigation (indeed of active manures generally) on the mixed herbage of grass land is greatly to develope the Graminaceous plants nearly to exclude the Legu- minous and to reduce the prevalence of miscellaneous or weedy plants but much to encourage individual species.Among the grasses according to locality or other circumstances the rough meadow grass (Poa trivialis) couch grass (Triticum repens) rough cock’s foot (DactyZis glomerwta) woolly soft grass (Holcus Zanatus) and perennial rye-grass (Lolium perenne) have been observed to hecome very prominent ; two or three only remaining in any considerable proportion after some years of liberal sewage application. But sewaged produce being generally cut or grazed comparatively young the tendency which the great luxuriance of a few very free-growing grasses has to give a coarse and sternmy later growth is not an objection asiu the case of meadows left for hay.The chemical examination of the grass grown at Rugby showed that at the stage of growth at which it was cut the sewaged grass contained a less proportion of dry or solid substance than the unsewaged; that the grass cut during the later portions of the season (both unsewaged and sewaged) contained less solid matter than that cut dixring the more genial periods of growth ; that the proportion of nitrogenous substance (and also of impure fatty or waxy matter) was much greater in the solid matter of the sewaged than in that of the unsewaged grass; that the propor- tion of nitrogenous substance was also much higher in the and ether.It melts at 224*5"C. to a reddish-brown oil. L higher temperstme it deflagrates diffusing at the same time a& Bromatic dour. It is an almost perfectly indifferent substance. 3 could not even succeed in preparing a compound with dichloride of platinum ;nitrate of silver however still gives even in very dilute alcoholia solutions tb yellowish -green amorphous pre- cipitate. When 6-nitraniline is submitted to the action of nitrous acid almost exactly the same phenomena are observed as those which occur in the preparation of the preceding compound. The crystals which have been deposited but which in this case exhibit a per-fectly distinct form are easily purified in the same manner. The B-diazo-amidonitrobenzol differs only in a few points from the a cornpound.It is equally insoluble in water and appears also to be as difficultly soluble in alcohol and ether. The two substances also seem to agree in their deportment with reagents a1 fss as could be decided by preliminary experiments. On the other hand the melting point. of /3-diazo-amidonitrobenzol is 195.5O C. consequently 29' lower than that of a-diaeo-amidonitro-beneol. The a compound crystallises as a rule in granular or rnoas-like Bhapes whilst the 6-diazo-amidonitrobenzol separates already during ita preparation in small though generally well- defined ruby or reddish-yellow prisms which by recry stallisation from &oh01 or ether may be obtained of a cousiderable size. On passing a current of nitrous acid gas into a very dilute alcoholic solution of dibromaniline the diazo-amidodibromobenzol ia obtained as a bulky light-yellow precipitate.Repeated washing with alcohol renders it perfectly pure. Diazo-arnidodibromobenzol has a great tendency to crystallise in different forms. From alcohol and ether in which it is very difficultly soluble even at the boiling temperature it crystallises in fine golden-pellow interlaced needles which melt at 167*5O C. but deflagrate at a higher temperature. On allowing an alcoholic VOL. XIX. F axmas ON A NEW CLASS OF ition to evaporate spontaneously yellowish-browu granules are .requently obtained which show a golden- yellow fracture and a radiating crystalline structure. On several occasions ad under conditions not accurately determined a-diazo-amidodi-bromobenzol prepared from not absolutely pure dibromaniline crystallised from ether in extraordinarily beautiful yellow or ruby well-defined prisms.As this form differing in such a characteristic manner from the yellow needles appertained to the dibromaniline obtained from dibromisatin I should have been inclined in spite of what I had previously stated in regard to dibromaniline to seek the cause of this difference in the dibro- maniline prepared by the different methods. I soon however convinced myself that the beautiful red crystals are converted on further re-cry stallisation from ether iiito the same golden-yellow hair-like needles. C,,H,C14N = {C6H,C1,N D~azo-amidodichZorob~zo7 C6H,Cl,(~H,)) is also prepared from dichloraniline and crystallises also in hair- like needles which are however distinguished from the bromine compound by their light sulphur-yellow colour.It is insoluble in water and very difficultly soluble in boiling alcohol and ether. It melts at 126*5OC. In their deportment with reagents diazo-amidodibromobenzol and diazo-amidodichlorobenzol exhi bit the greatest analogy to the nitrogen-substituted auiline-derivatives already described whilst under the same conditions they yield corresponding products of decompssition. They also form precipitates with nitrate of silver. Their basic character however has completely disappeared; they no longer give platinum-salts; in fact they possess more the character of an acid than that of a base as they dissolve with ease in alcoholic potash forming a reddish-brown solution from which the original substance is precipitated in a perfectly unaltered state on the addition of an acid.Lt is how- ever not possible to prepare salts of a definite composition. Aqueous potash has no action upon these bodies. From what has been stated it is obvious that the acidifjmg in-fluence exerted by nitrogen when taking the place of hydrogen in aniline is repeated in an equal degree with the substitution-products of that body. AXD UTILIZAT€@W OF TOWN SEWAGE. 1. TABLEIX (continued). Plot 2. Plot 3. Plot 4. ’* 3 000 Tons 6,000 Tons 9,000 Tone Unsewaged* sewage. Sewage. Sewage. Gallona. Gallons. &Ilona 1861-Graas (alone)............ 180 178 151 1862-Grass (with oilcake) ...... 74 60 38 Orass (a without 4 with 1e63-{ oilcake.. .......... 154 132 101 Means.. 136 123 97 1 I I & 8. d. $ 8. d. e 8. d. 1861-OM (alone) ............ 5 19 10 6 18 8 5 0 11 1862-Oms (with oilcake) ...... 294 200 167 (a without + with M3-{O~ES I 627 481 377 oilcake ............ -I I I 1 Means.. 4 10 7 4 2 3 3 4 8 It may be stated generally that when the cows were fed on grass alone as much as they chose to eat a given weight of the animal was more productive both of milk and increase but espe- cially of milk on the unsewaged than on the sewaged grass. More milk was also produced from a given weight of the un-sewaged grass reckoned in the fresh or green state than from an equal weight of the fresh sewaged grass.Of dry or solid sub-stance however a given weight of that of the sewaged grass produced on the average more milk than an equal weight of that of the unsewaged. The milk from the cows fed on the sewaged grass was,upon the it The value of the milk “exclusive of oilcake,” is reckoned by deducting the cost of the cake consumed less the estimated value of the manure it yields fromthe gross value inclusive of oilcake ;and the amount of milk ‘‘exclusive of oilcake,” by deducting from the gross amount of milk with oilcake at the rate of one gallon for every 8d. of deducted value. Suchestimates are however obviously only approxima-tions to the truth. 4 LAWES AND GILBERT ON THl3 COMPOBXTION VALUE whole slightly the less rich containing generally somewhat less casein butter sugar and total solid matter (though more mineral matter) than that from the unsewaged; but when oilcake was given with the grass whether sewaged or unsewaged the richness ofthe milk mas notably increased The productive quality of the grass was very different in dif-ferent seasons and at different periods of the same season being very inferior in the wet and cold season of 1862 and towards the close as compared with the earlier periods of the seasons.Without commenting further on the difference of result ob- tained under different conditions of season or under other varying circumstances it will be suflicient briefly to call attention to the more general results which the records in the table bring promi- nently to view and to the practical conclusion which on a careful consideration of all the circumstances and details may seem to be safely deducible from them.It is seen that whether we reckon the total amount of food yielded per acre or the amount or the value of the milk ob- tained from the consumption of the produce of each acre there was a very great increase varying from two to three-fold ac- cording to season by the use of sewage. The land upon which these experiments were made was good feeding pasture of pro-bably more than average quality and the natural yicld without sewage was therefore correspondingly high. Taking into con-sideration this fact and other circnmstancea uiider which the results were obtained it is concluded that if not larger amounts of total produce per acre at any rate larger amounts of increase for a given quantity of sewage may be expected when it is applied systematically over large tracts of land with a view to the pro- duction of grass and milk.It is estimated that with 5,000 tons of sewage per acre per annum judiciously applied to Italian rye-grass or meadow-land properly laid down to receive it an average gross producc of not less and perhaps more than 2,000 gallons of milk per acre per annurn might be anticipated; and it may be observed that 1,000 gallons of milk at 8d. per gallon would represent a gross money return of 833 6s. 8d. Putting the result in another may it may be stated that it required according to circumstances the consumption of between 5 and 6 tone of grass for the production of J ton of milk; and if we reckon 6 parts of grass for 1 of milk and 30 tons of grass per AND UTILIZATION OF TOWN SEWAGE.acre this would give a gross return in value of milk at 8d. per gallon of something over X37 per acre or of about 25s. per ton of grass consumed. Still another illustration of the important bearing of the ques- tion of the utilization of the sewage of our town populations upon the re-production of food may be given. Supposing the whole of the sewage of a given population (which however would seldom be the case) were applied exclusively for the growth of grass for the production of milk the result would be an increased yield of about 2+ pints of milk per week or about +lb.per day per head of such population. So far as the sewage were so applied a por-tion of the milk produced would of course be represented in con- sumption by its equivalent in butter and cheese. A portion of the grass would however be used directly for the production of meat; and in addition to the milk and meat produced by the consump- tion of the grass a large amount of solid manure would be obtained which would be applicable to arable land for the growth of corn and other rotation crops. It would appear then that if town sewage were to a great extent utilized by the application of something like 5,000 tons per acre per annum to Italian rye-grass and meadow-land a direct result would be a very greatly increased production of important articles of human food which are at present both scarce and dear.But the question remains-wdd the sewage by such an applica- tion be sufficiently purified to allow of the drainage from the irrigated land being turned into rivers which are to be used as a water-supply for other towns ? Some light will be thrown on this subject by the results next to be considered. In order to determine how far in the experiments at Rugby the sewage was deprived of its manurial or putrescible constituents in its passage over and through the land samples of the drainage water were collected for analysis in each field simultaneously with those of the sewage commencing in May 1862 and ending in Octobei; 1.863. In all 68 partial analyses of drainage-water corresponding in detail with those of the sewage were made.A few other analyses in much more detail were made of the sewage and drainage of the season of 1864. The results of the large number of partial analyses are summarized in Table X which shows in parallel columns the average composition of corresponding samples of sewage and drainage. 116 LAWEB AND GILBERT ON THE COMPOSITION VALUE Mean Composition of the Rugby Xewage bgwe amtication and of the Drainage-water from the Irrigated Land in the Seasons 1862and 1863. Grains per Gallon. ~~~~ Five-Acre Field. Ten-Acre Field. The two Fields. Conntitueiits. 1 1 Sewage. Drainage. Sewage. Drainage. Sewage. Drainage. 1 I Season 1862 j May-October both inclusive.I 19 Samples. Inorganic 24 -89 2 92 14-69 17 -14 i39 Total... 40 -36 3 91 41 -20 4 -51 1 Inorganic 34.49 34JO 53-44 36 *01 7 -83 7 -18 7.71 7-56 Total... 39.98 44'93 41-16 43 '57 Total inorganic ... 60.16 36.31 67-27 40.84 58 *72 38 *93 Total orgauic ....... -22 -52 --8 -58 24 -74 9.22 23 *63 8 -95 I --7 Total eolid matter... 82-68 44.89 82 01 60 -06 82 35 47 #88 1-52 0 33 1-44 0 *29 4 -26 1.85 4 -20 1-41 1 -I Total... 5.78 2-18 6.64 1-70 Season 1863; November 1862-0ctober 1863 both inclusive. 22 Samples. 22 Samples. 45 Sam les. 43 Samples. 54.93 3-95 37-82 3 -06 I 27 -35 25 -99 3 -29 26 *69 2 '37 Total... 60.92 5 -43 Inorganic 39'57 3p5 38 -77 39-98 8 -35 8 -30 7'98 7-73 solution ... Organic**. --,-46 -~n iTotal...47'92 I 46-01 47.07 47 -71 Total inorpanic ... 78-98 40.69 73.70 46 -28 43.04 Total organic ...... 35 -70 8 *87 34 -29 11-27 10.10 1 -Total solid matter. .. 114.68 49-56 107 -99 63'14 In suspension 1*98 0 -31 0.23 --5 *69 1.85 1*28 -I Total ... 7 '67 2-16 7.79 1-51 It is seen that of matter in suspension in the sewage nearly the whole both inorganic or organic was retained by the soil; and probably a considerable part of the little which the drainage- water contained was derived from the soil itself. Of matter in solution on the other hand a gallon of the AND UTILIZATION OF TOWN SEWAGE. drainage-water contained on the average much about the same amount both inorganic and organic as a gallon of the sewage; though doubtless a corisiderable portion of the soluble matters in the drainage had their immediate source in the soil-the sewage giving up valuable manurial matters to the soil and the fluid in its turn taking up substances from it.It is important to remark that the drainage from the more porous and less naturally fertile soil of the five-acre field (which however gave the largest amount of increase for a given amount of sewage) contained less of almost every constituent or class of constituents enumerated than did that from the more argil- laceous and more naturally fertile soil of the more steeply sloping ten-acre field. The result is particularly marked in the case of the ammonia. The fact here indicated is of considerable practical as well as scientific interest; and it is perfectly consistent with the results of common experience which tend to show that a soil which may contain a comparatively small proportion of clay but which is thoroughly porous is as a rule much better adapted for sewage irrigation both as regards the utilization aud the purifica- tion of the sewage than one which though richer in clay and of higher natural quality is but imperfectly permeable by the fluid.The results given in Table XI show in more detail the changes in the composition of the fluid in its passage through the soil. They relate to samples of sewage and drainage taken in another field at Rugby during very dry weather in the summer of 1864. The plan of collection was to take of sewage about a gallon and of drainage about half :L gallon eight or ten times during the ten or twelve working hours of the day; at the end of the day after well shaking to take a gallon from each mixture; and to repeat this for six consecutive days until six gallons of each were obtained when after well shaking a two-gallon sample of each was bottled off for the purposes of analysis.VOL. XIX. K 118 LAIVES AND GILBERT ON THE COMPOSITION VALUE TABLE XI. Detailed Composition of samples of the Rugby Sewage before application and of the .%ainnge-water fyom the irrigated land collected July 1864. Grains per Gallon. Constituents. Collected Collected July 6-11. July 13-18. Inorganic matter :-Sewage. Drainage. Sewage. Drainage. Oxide of iron and alumina...... 4*57 .. 6.30 .. Lime. ....................... 4 *48 .. 3.75 .. d Magnesia .................... 0 .65 .. 0 -25 .. .r( Carbonicacid ................ 3.25 .. 2 .17 .. Es Phosphoric acid ............. 1.84 .. 1-14 .. .. P Silica sand &c. .............. 31 $0 .. 39.30 - z -d Total ................ 46 39 .. 52.91 .. l+ Organic matter ................ 40.40 .. 32.40 .. Total matter in suspension.. 86 T9 -.. 85.31 .. ~~~ ‘~norganic matter :-Oxide of iron &c ............ Traces. .. 1.25 0 -25 Lime.. ...................... 8.45 10.25 8 .23 10 -08 Magnesia .................... 1*76 1.69 1 80 1.69 Soda (1) ...................... 5 46 0 38 5 .24 2.30 Chloride of sodium (1).......... 6.82 9 .73 8 .53 9.21 Chloride of potassium (1) ......6 .08 1*50 6 .l’I 2 .34 .A o 2 < Sulphuric acid ................ 4.39 6 55 4.01 6 .75 CI Phosphoric acid .............. 1.28 0 .44 1.66 0 .32 g Cartwnio acid ................ 8 83 6 -Id 7 .42 7.01 1.80 0 -80 1-00 0 *80 c-( Silica.. ...................... ---- -Total.. ................ 44.87 37.52 45.31 40 -7.5 Organic matter ................ 11 -20 ‘7.80 10 -00 7 -05 --__ -__I 56 -07 46.32 55 -31 47 -80 91.26 37 *52 98 *22 40.75 51 *60 7 -80 42.40 7 05 142 -86 45 -32 140,62 47.80 -__ --I-3 *84 0 -94 3.90 1-48 9 .07 5 *54 9 5% 7-17 7 03 6 *61 8 .lo 6 TO 2 -92 .. 2 -42 .. 5 -74 0.98 6.36 0 -92 8 .66 0 .98 8 *78 0 *92 .... (3) 1-33 .. :4) 1.41 (3) 4.227 Nitric acid = 1’096 Nitrogen = 1.331 Ammonia (4) 4-483 ..= 1.162 = 1’411 .. AND UTILIZATION OF TOWN SEWAGE. The soil was light and gravelly with a gravelly subsoil; but an examinat,ion of the figures in Table XI shows that it had dorie the work of absorption at any rate as well if not better than on the average did the soils in the other fields. It Was intended to take samples for detailed analysis from this field under various conditions of the weather but owing to the continuance of the drought this could not be accomplished. In judging of these results as well as those already considered it must of course be borne in mind that excepting when the land is already saturated with water a gallon of drainage will represent much more than a gallon of sewage; and that hence the amount of any constituent of the sewage found in a gallon of the drainage must have been derived from more than a gallon of the former.The non-retention of valuable manurial matters by the soil was therefore not so great as would at first sight appear on an inspection of the comparative composition of equal volumes of the sewage and of the drainage. As in the larger number of cases so in these the quantity of matter in suspension in the drainage was very small and being obviously in great part derived from the soil it was not submitted to quantitative analysis. A considerable proportion of the phos- phoric acid of the sewwge was in suspension but there was none of' it in suspension in the drainage the whole of the portion so existing in the sewage having been retained by the soil.It is satisfactory to observe that among the inorganic constituents in solution in the sewage by far the larger proportion of those which are perhaps the most likely to become relatively deficient was retained by the soil. Thus smaller proportions of both the potassa aod the phosphoric acid of the sswage passed off in the drainage than of any other constituents. Soda was also retained by the soil to a considerable extent magnesia in a less degree and lime less still. Of lime indeed there was more in a gallon of drainage than in a gallon of sewage; of sulpburic acid also there was considerably more in the dr~iinage than in an equal volume of the sewage. Lastly of soluble silica a notable portion passed off in the drainage.Of organic matter in solution a very considerable quantity was found in the drainage-water. The character of the soluble organic matter in the drainage is however very different from that in the sewage. It contains very much less ammonia or arnmonia-yield-ing matter ; and especially in periods of active vegetation will K2 120 LAWES AND GILBERT ON THE COMPOSITION VALUE doubtless frequently he derived from vegetable matter within the soil rather than directly from the sewage. A very importaut point to remark is that whilst the sewage scarcely contained an appreciable amount of nitric acid the drainage contained more nitrogen in that form than as ammonia; the result being that the soil had retained a considerably less pro- portion of that important manurial constituent of the sewage than would have been supposed had only the more partial analyses been made.The general result was that practically the whole of the in- soluble or suspended matter of the sewage was retained by the soil; and that of the constituents of the sewage whether in sus-pension or in solution those which are of the most value because the most liable to become relatively exhausted were the most efficiently retained. Nevertheless the drainage- water still retained so much of potassa phosphoric acid ammonia and nitric acid as clearly to show that the sewage had not been perfectly deprived of its valuable manurial matters and also so much of total soluble matter especially of soluhle organic matter as to shorn that it had not been by any means perfectly purified.There is indeed a limit to the power which a soil possesses of removing substances from solution or of preventing those already absorbed from being dissolved in water passing through it the result being dependent on the physical and chemical characters of the soil itself and on the amount and composition of the fluid passing through it. So far as the soluble organic matters of' the drainage are derived from vegetable matter within the soil it is a quealion whether there will not always be a considerable amount in that passing from land covered with luxuriant vegetation. So far however as the nitrogen of the drainage exists in the form of nitric acid it is a pretty satisfactory indication that the organic matter has to a great extent already passed the stage of deleterious putrescence.In the Rugby experiments the arrangements were not such as to allow of the water drained from one portion of the land being passcd over another ; but at Beddington near Crogdon a great portion of the water docs duty twice and sometimes three times; and from results kindly communicated by Mr. Lat ham the engineer to the Croydon Board of Health and given in the following table it would appear that there the water eventually passes from the land in a state of much greater purity than was the case in the Rugby experiments. AND UTILIZATION OF TOWN SETS'AGIL TABLEXII. Partial Analyses of the Croydon Sewage before application of the Drainage-water from the irrigated land and of the River Wandle above and below the Drainage OzctfuUfrom the irrigated land.I Croydon. I River Wandle. I I I Below Constituents. Grains per gallon. Inorganic matter .............. Organic matter ................ 52.20 1*44 2 *08 Total Bolid matter .. Ammonia ..................... 6 70 0.21 0 *18 0.18 The figures show much about the same amount of ammonia in the sewage of Cropdon as was found on the average in that of Rugby; but the amount in the Croydon drainage was extremely small. It is unfortunate that the quantity of nitric acid was not also determined; but we are informed that it undoubtedly exists in some amount in the drainage from the Beddiiigton meadows.Still although formerly the Croydori Board had to meet numeroils law-suits on account of the pollution of the river by the sewage the fluid is now so far purified before being discharged that tliose having the right of fishing in the river have found it worth while to fix gratings to prevent the fish going up the main outfall from the sewage -irrigated land The results obtained in regard to this part of the subject-that of piirification-however interesting and importaut must still be looked upon as little more than initiative; but there can be no doubt that when large quantities of sewage are applied to grass-land the arrangements should be such as to allom of the drainng::c-water being collected and re-used in si:ch a mantier as toir1sui.e as far as possible both complete utilization and complete purific at'1011.It must be admitted however that further expericnccl arid fiirthcr investigation arc still wanting to determinewhat arnoiint of sewage provided the drainage-water be properly re-distri bnted caii tx 122 LAWES AND GILBERT ON THE COMPOSITION VALUE safely applied to a given area under different conditions of soil and subsoil and under different conditions of serson so as to insure its sufficient purification. Experience of Common Practice in the Utilization of Sewage. Leaving the results of experimental inqairy it will be well briefly to notice those of practical experience hitherto in regard to the value and utilization of town sewage. The instance most frequently quoted is that of the neighbourhood of Edinburgh relating to which some particulars are given in the following Table :-TABLEXIII.Relating to the Sewage-irrigated Meadows near Edinburgh. 'Imperial Approximate Approximate Population Quantity of Names of Meadowa. Acres under contributing Sewage available Irrigation* to each Acre. for each Acre. Tons. Lochend Spring Gardens andCraig- } entinny .................... 285 337 20,500 ltoseburn and Western Dalry ...... 80 7 12 1'1,080 Quarry Holes.. .................. 8 562 65,000 Broughton Burn ................ 6 1,666 102,000 The Grange.. .................... 16i 302 9;;ooo These tabular statements are chiefly based upon direct informa- tion obtained in part from Mr. McPherson the Edinburgh City Surveyor and in part from the occupiers or managers of the respective meadows.To prevent misundei~standing however it must be explained with regard to them that as water-closets are not universal arid as the sewage is frequently allowed to pass unused the records of the amount of population contributing to and of sewage available for each acre do not show the amounts actually utilized but only approximately the total amounts avail- able whether used or wasted. Sewage has been applied to some portions of the land in the neighbourhood of Edinburgh for about 200 years to a considerable portion for more than 60 and to most of that now undcr irriga- tion for more than 30 years. In two instances arrangements have been made for raising the sewage by pumping an iuconsiderable AND UTILIZATION OF TOWN SEWAGE.number of feet; but the cost has been found too great to allow of a sufficient quantity being applied per acre and hence the appli- cation in this way has beeu much limited if not on some portions of the land entirely abandoned. The application is confined to meadow land and Italian rye-grass and the distribution is entirely by means of open runs. When Italian rye-grass is grown the land is periodically broken up and one or two other crops taken without sewage before laying down again to grass. The applica- tion to ordinary rotation crops on arable land forms no part of the system adopted. There is no doubt that at Edinburgh larger amounts of sewage are applied per acre than anywhere else and that it is under those conditions that there are there obtained larger amounts of produce per acre than anywhere else Nor is there any doubt on the other hand that there is at Edinburgh not only very great waste of manurial constituents but very imperfect purification of the sewage.Hence the experience there however interesting and important in some points of view cannot be taken as the founda- tion either of estimates of the value realizable in practice by the utilization of given amounts of sewage or of the sewage of a given population or of safe conclusions as to the amount of sewage that can advantageously be applied per acre when the drainage has to be passed into a river which may have to serve as the water-supply of other towns instead of as at Edinburgh having a11 immediate outfall into tlie sea.It may be mentioned that generally four or five crops of grass are obtained per acre annually amounting according to circum- stances to 30 40 50 60 and even more tons per Imperial acre and selling for prices varying from $8 to over 240 per acre but averaging perhaps about $25. These results are indeed suffi-ciently striking and well merit careful inquiry and consideration ; but for the reasons above stated the exact practice of Edinbiirgh is not applicable to towns generally and is especially inapplicable to inland towns. Table XIV summarizes the results of the experience of the most important instaiices of sewage utilization in other localities. 124 LAWEB AND GILBERT ON THB COMPOSITION VALUE TABLEXIV.Relating to Sewage-irrigation in &xrious localities. Acres. Annual Towns. kiginal Xeduced Crops &c. Payment o Towns. Alnwick . . . . 6,500 270 0 Arable and grass ;abandoned Nothing Carlisle .... 22,000 70 .. Meadow-grass; all grazed 2 Croydon .... 16,000 250 .. Meadow and rye-grass 3300 Malvern .... 4,000 50 8. Grass Nothing Rugby.. .... 6,700 f 190‘1280 20 100 Meadow and rye-grass Meadow ; chiefly grazed } 250 Tavistock.. .. 6,000 95 .. Grass Nothing Watford ,.. 4,000 210 { 3; Rye-grass-SummerMeadow-grass- Winter } &lo Worthing .. 7,000 42 .. Grass ; not yet at work Nothing At Alnwick the late Duke of Northumberland put down machinery and piping for the distribution of the Eewage of the town over about 270 acres of mixed arable and grass land.After ft very short time the tenants who had the free use of the sewage for the cost of its application abandoned it altogether ; and the Bailiff of the District who reports the failure expresses his opinion strongly against the general applicability of sewage to arable land. At Cadisle the sewage of only a portion of the town is utilized. It is deodorized by Mr. McDougall’s disinfecting fluid and raised by steam power some 10 or 12 feet into an open Cut from which it is diverted for application to the lard by moveable iron troughs. It is estimated that from 8,000 to 9,000 tons of sewage are applied per acre per armurn. It is understood that little or nothing is realised by the town; but that the tenant malies a considerable profit by sub-letting the sewage-irrigated laxd for grazing purposes.In the neighbourhood of Croydon as already referred to the sewage of nearly 20,000 persons is applied to about 250 acres of meadow and Italian rye-grass. It is calculated that more than 6,000 tons of sewage are available for each acrc. A considerable portion of the fluid is used two or three times over; and it finally AND UTILIZATION OF TOWN SEWAGE. passes from the land pretty satisfactorily purified. It is esti-mated that after making deduction of' &4 for rental the gross return per ton of sewage applied is at the present prices of the produce with Italian rye-grass from fd. to Id. and with meadow grass from id.to 2d. The sewage is not applied in any systematic manner to other crops but it has been tried on a small scale to root-crops. An enlargement of the area of irrigation is contem-plated which will if carried out somewhat reduce the amount of fluid and excretal matters available per acre below the quantitics above stated. About 12 years ago arrangements were made for collecting the sewage of Rugby in a tank from which it is pumped by a 12-horse power engine through iron pipes laid down for the distribution over about 470 acres of mixed arable and grass land. TJp to last year 190 acres were held by Mr. James Archibald Campbell but he has gradually limited the area of application and during the last few years has abandoned the use of hose and jet excepting occasionally on a small scale and confined the application almost exclusively to from 12 to 20 acres of meadow and Italian rye- grass.The remainder of the land amounting to about 280 acres has passed through the hands of two tenants both of whom are said to have sustained considerable loss. The last of the two had confined the applicatiou almost exclusively to about 100 acres of grass land and applied the sewage almost entirely by open runs. The whole is now in the hands of the landlord Mr. G. H. Walker who it is understood is contemplating the abandonment of the use of steam power pipes and hose and jet and the application to a limited area by means of gravitation. The general result at Rugby is then that after about a dozen years of practical experience with arrangements adapted for the applicatioii of small qiiantities of sewage per acre to arable as well as to grass land and to all crops the area has been greatly limited the use to any other crops than meadow and Italian rye- grass is quite exceptional and the application by means of steam-power pipes and hose and jet will probably soon be entirely abandoned.It may be added that at the time of the experiments of the Commission the sewage which was considerably stronger than that of the Metropolis cost the tenarits only about jd. per ton at the hydrants in the fields ; yet rather than incur the loss of using it at that cost both were glad to get rid of it to the Com-mission at rates which though three times as high during the 126 LAWES AND GILBERT ON THE COMPOSITlON VALTJE six summer as during the six winter months averaged the year round scarcely but very nearly Id.per ton at the hydrants. Some’years ago the Earl of Essex laid down pipes for the appli- cation of the sewage of Watford by pumping and hose and jet to about 210 acres of mixed arable and grass land. The results which hisLordship obtained on the application of only 134 tons of sewage per acre to wheat have frequently been held to be conclu- sive proof of its applicability in small quantities per acre over large areas to arable land and to all crops. But in the evidence given by his Lordship before the Sewage Committee of 1862 lie stated very emphatically that his great error had been the piping of too much land; that he required 5,000 tons per acre for 10 acres of rye-grass ;and that applying the remainder to 35 acres of meadow he had none to spare for wheat.In other words although the abandonment of one acre of rye-grass would set free sewage enough for nearly 40 acres of wheat if applied only at the rate which yielded the large gross return per ton of sewage so frequently quoted yet his Lordship’s practical experience had led him to prefer the application to the one acre of rye-grass rather than to the nearly 40 acres of wheat. Further his Lordship gave it as his opinion that sewage would not be profitable to the farmer unless he could have it at from &I. to ad. per ton. Referring to the question of the application of sewage to corn crops it may be stated that in an experiment made by the Coni-mission at ,Rugby with oats a very high gross money return per ton of sewage was also obtained.The experiment was made in the unusually productive season of 1863 and with sewage of about double the average strength of that of the Metropolis applied during a period of very dry weather. The results were therefore quite exceptional and cannot be taken as affording any indication of what might be expected from the application of small quantities of sewage to corn crops generally on different soils and on the average of seasons There cannot indeed be a doubt that to obtain a maximum gross value of produce from a given amount of sewage it should be applied in small quantities per acre and in dry weather.But sewage is produced in large daily amount at all seasons and must be disposed of as soon as it is produced. It must therefore be applied in winter when of comparatively little value as well as in summer when of more and it would frequently be quite inapplicable to arable land. Moreover to obtain an increased gross money return per ton of‘ sewage by using it on a AND UTILIZATION OF TOWN SEWAGE. comprehensive scale for corn and ofher ordinary rotation crops would involve the extra cost of main distribution over at least a ten-fold if not frequently a twenty-fold area and require the application to a great extent hy the expensive means of pipes and hose and jet instead of by the economical one of open runs.At Malvern and Tavistock the application of sewage to grass land has now been carried on for some years but at Worthing it has only very recently been commenced. From this short review of the experience of practical men who have undertaken the utilization of sewage with a view to profit it appears that wherever arrangements have been made for the application of small quantities over large areas to corn and other rotation crops on arable land and by means of pipes and hose and jet the undertaking has either been entirely abandoned or the area greatly limited and the application confined almost exclu- sively to meadow and Italian rye-grass. On the other hand the undertakings which have been the most successful from the agri- cultural point of view are those in which the arrangements have been adapted for the almost exclusive application to grass and the application to other crops is only exceptional.The practical conclusions deducible from the whole inquiry may be briefly stated as follows :-1. It is only by a liberal use of water that the refuse matters of large populations can be removed from their dwellings without nuisance and injnry to health. 2. That the discharse of town sewage into rivers renders them unfit as a water supply to other towns is destructive of their fish causes deposits which injure their channels gives rise to emana- tions which are injurious to health is a great waste of manurial matter and should not be permitted. 3. That the proper mode of both utilizing and purifying sewage is to apply it to land.4. That considering the great dilution of town sewage its con-stant daily supply at all seasons its greater amount in wet weather when the land can least bear or least requires more water and the cost of distribution it is best fitted for application to grass which alone can receive it the year round. It may however be occasionally applied with advantage to other crops within easy reach of the line or area laid down for the continuous application to grass. WANKLPN ON A NEW METHOD 5. That having regard both tourban and rural interests an appli-cation of about 5,000 tons of sewage pw acre per annum tomeadow or Italian rye-grass would probttbkg in the majority of cases prove to be the most profitable mode of utilization though the quantity would have to be reduced provided experience showed that the water was not sufficiently purified ;and it is pretty certain that the farmer would not pay jd.and it is even very doubtful whether he could afford to pay id. per ton the year round for sewage of the average strength of that of the Metropolis (excluding storm- water) delivered on his land. 6. That the direct result of the general application of town sewage to grass land would be au enormous increase in the pro- duction of milk butter cheese and meat; whilst by the con-sumption of the grass a large amount of solid manure applicable to arable land and to crops generally would be produced. 7. That the cost or profit to a town of arrangements for the removal and utilization of its sewage must vary very greatly according to its position and to the character and levels of the land to be irrigated.Where the sewage can be conveyed by gravitation and a sufficient tract of suitable land is available the town map realize a profit; but under contrary conditions it may have to submit to a pecuniary sacrifice to secure the necessary sanitary advantages.

ISSN:0368-1769    

DOI:10.1039/JS8661900080

出版商:RSC    

年代:1866

数据来源: RSC

摘要:

WANKLPN ON A NEW METHOD X3.I.-On a New Nethod of Forming Organo-metallic Bodies. By J. ALFREDWANKLYN, Professor of Chemistry at the London Institution. EIGHT years ago I showed that sodium attacks zinc-ethyl precipi- tating zinc and forming sodium-ethyl. Having observed similar reactions between zinc-ethyl and the metals potassium lithium calcium and strontiiim and having regard to the great facility with which these displacements of metal are effected I was led to compare them to the well-known electro- chemical precipitation from ordinary inetallic solutions and to regard them as examples of a very general method of producing a number of the orgsno- metallic bodies. On the prescnt sccasion 1 have to announce a different method of procedure.Iiistead of taking an organo-metallic compound of OF FORMING ORGANO-METALLIC BODIES. a less positive metal and attackingit with a more positive metal I take an organo-metallic compound of one of the most positive metals arid attack it with mercnry or with an amalgam or a mix- ture of mercury with some other metal. The result of the opera- tion is an amalgam of mercury with the positive metal whilst the organic radical unites either with the mercury or with the other metal. Thus the new method of forming organo-metallic bodies consists in utilizing for that purpose the great affinity of mercury for the alkali-metals. The following examples will serve to characterize it :-Mercury Zinc and Sodium-ethyl. When the crystalline compound of sodium-ethyl and zinc-ethyl,* which is prepared by treating zinc-ethyl with sodium is heated in the water-bath with mercury and zinc it is rapidly resolved into zinc-ethyl and sodium-amalgam according to the followiug equation :-In one experiment I took about lfi grms.of the compound con- taining sodium-ethyl and sealed it up with mercury and zinc and heated in the water-bath. The result was a quantity of pretty pure zinc-ethyl not less than 7 grms. and an amalgam of sodium very rich in sodium. I made an analysis of a portion of the 7 grms. of zinc-ethyl. It did not contain so much as 0.5 per cent. of sodium Mercury Magnesium and Sodium-ethyl. Some of the crystals containing sodium-ethyl were sealed up with mercury and magnesium-wire. After a short heating in the water-bath they did not form a liquid as in the last case but a white solid.On opening the tube it was observed that the mer-curyt was very considerably alloyed with sodium and that the white solid,which did not fume took fire spontaceoualy in the air and contained magnesium and zinc but not more than traces of sodium. Evidently therefore the reaction was essentially- * Ann. Ch. Pharm. (1858). + The mercury effervesced furiously with water much more violently than a simple amalgam of sodium does. It would seem that the presence of a little metalIic magnesium in sodium-amalgam heightens the activity of the amalgam. 130 CHURCH ON NEW AND RARE CORXISH MINERALEL 44g + M-g + 2NaC,H5 = &€@a + Mg(C,H,),. the magnesium-ethyl forming a compound with the zinc-ethyl pre- viously in union with the sodium-ethyl.Mercury Copper and ~oddium-EthyI.-Mercury Iron and Sodium-E1hyl.-Mer cury,Silver and Sodium-Ethy1. The result in each of these three cases is mercury-ethyl and sodium-amalgam the presence of the copper or iron or silver appearing to have little or no influence on the course of the reaction. The foregoing reactions exhibit sodium-ethyl in a new light. It is a sodium compound which possesses the very singular property of giving up its sodium to mercury. In conclusion I would remark that since the organo-metallic bodies are liable to be attacked by mercury very little reliance can be placed on those vapour-density determinations of orgauo-metallic bodies which have been made by the method of Gay-Lussac in- volving as it does the employment of mercury in contact with the organo-metallic body in a state of vapour. Most probably the ano- malous results obtained by Buckton and Odling viz. that the vapours of aluminum-methyl and aluminum-ethyl do not expand re- gularly depend upon the decomposition 0f those compounds by the mercury of the bath. And most probably vaponr-density determi- nations of these compounds will be found to yield perfectly intelli- gible and normal results when the method of Dumas instead of the method of Gay-Lussac is employed.

ISSN:0368-1769    

DOI:10.1039/JS8661900128

出版商:RSC    

年代:1866

数据来源: RSC

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130 CHURCH ON NEW AND RARE CORXISH MINERALEL XI1I.-Chemical Researches on A'ew and Rare Cornish Minerals. By -4. H. CHURCH, M.A. Professor of Chemistry R.A. College Cirences ter. (Continued from vol. III. new series p. 259.) IV.-A New Hydrated Cupric-aluminum Subhate. I HAVE been engaged for some time in analysing certain chry-socollas containing aluminium similar to the Tuscan specimens CIIURCH ON NEW AND RARE CORNISH MINERALS. 131 described by Delesse. But no definite cornyosition was presented by these bodies ; indeed they were evidently mixtures in most in- stances In some of the specimens I found as B er thier had previously stated much sulphuric acid and at last I have obtained from Mr.Talling some specimens of a mineral almost free from silica and containing over 13 per ceut.of sulphuric acid. I noticed it in Mr. Talling’s collection was struck by its appear- ance and at once secured a few fragments. The analyses proved satisfactory and accordant and showed the mineral to be a new and undescribed species. I purpose naming the mineral Wood-wardite after my valued friend the late Dr. s. P. Woodward. I shall be glad if this slight act of homage to the memory of an eminent man of science serve to recall the labours of a palzon-tologist who was well versed likewise in chemical geology. Woodwardite occurs in stalactitic forms consisting of minute botryoidal aggregations. It often constitutes a crust about +th of an inch in thickness and possessing the peculiar rippled appearance well seen in some specimens of langite.Woodwarditc presents a most striking appearance when viewed with an 18 inch objective in the microscope the inammillarp or botryoidal aggregations heirig arranged in irregular columiiar masses. No trace of crys- talline structure has yet been detected. The mineral is perfectly uniform in appearance and evidently free except where in contact with its matrix from all admixture. To the unassisted eye Woodwardite appears nearly opaque but under the microscope the globules of which it consists are seen to be translucent. The lustre is between waxy and dull. The colour of the mineral is a rather greenish turquoise-blue. The streak and powder are pale blue. The mineral though it readily falls to a coarse powder pre- sents a peculiar toughness and tendency to cohere under the pestle resembling caniphor and sal-ammoniac in this respect.The hardness is about 2. The specific gravity is about 2.38. This determination is approximative only; it was made with a specimen freed from interstitial air but containing a large quantity of hygroscopic or accidental moistnre about 13 per cent. in all probability. Woodwardite is tasteless and without odour. It dissolves readily in dilute acids a minute residue about 1 per cent. of gelatinous silica remaining unaffected. 132 CHURCH ON NEW AND RARE CORNISH MINERALS. Heated in a bulb-tube before the blow-pipe it gives off a large amount of water with a slightly acid reaction the residue becoming olive-brown and finally black.Heated to 100' the blue tint of the mineral thereby becomes richer. In vacuo over oil of vitriol woodwardite loses a somewhat variable amount of water Like many other uncrystallized minerals it is hygroscopic and if dried merely between pieces of filtering paper would be found to give a different formula on a dry and on a damp day. One determination of this accidental water gave 13-33 per cent. another a considerably smaller proportion. But the vacuum-dried mineral loses a constant amount of water at looo; while the mineral dried at 100' suffers a considerable and perfectly definite further loss at a temperature below redness. Woodwardite contains traces of phosphoric acid lime and magnesia; the percentage of phosphoric acid has been determined the lime and magnesia do not exist in sufficient quantity to be estimated.The analysis of the mineral offers no difficulty in one inctance (Anal. 111) the sample for analysis was thorouglily washed before being employed. The wash waters contained a minute trace of copper. Analyses I and I1 were made by my assistant MF. R. War-in g to n Junior. I. 5.47 grains of the mineral dried in vacuo gave :--06 grain of Sio,. -21grain of H,O at looo. 2.56 grains of CuO. 1.00grain of A1,0,. 23-00grain of BaSO,. 11. 10.19 grains dried in vacuo lost at a red heat :-2.41 grains of H,O; and gave 3.67 grains of BaSO,. III. *4gramme dried at looo gave :-0005 gramme of SiO,. 0073 gramme of H,O at a low red heat.*191 gramme of CuO. -071 gramme of A1,0,. 01605gramme of BaSO,. IV -5725 gramme dried iu vacuo gave :-*0035gramme of SiO,. *0300gramme of H,O at 100’. 00955gramme of H,O at a low red heat. 0267 gramme of CuO. *099 gramme of A1,0,. -209 gramme of BaSO,. V. $246 gramme dried in vacuo gave :-0014gramme of H,O at 100”. VI. *271gramme dried in vacuo gave :-0015gramme of H,O at 100’. The preceding analytical results point without doubt to a definite formula for the mioeral not only after it has become of constant weight in vacuo hut after drying at 100’ C. To aualyse the miueral indeed exactly in its natural conditioc of moisture would be useless for as the atmospheric water increases or diminishes so does that of the mineral.But in vacuo over oil of vitriol Woodwardite acquires in the course of an hour or two a perfect constancy of weight and composition. The formula which suggests itself for the mineral in this state is- 2Cu~’SO,.5Cu”H20,.4Al‘‘‘I130,.4H,0. This formula demands the percentages given below :-7 CU”0.. ........ 557.5 Theory. 46-67 Experiment.(mean.) 46.83 2 A1;(‘03 ........ 206.0 17.27 17.66 2 SO .......... 160.0 13.42 12.50 15 H,O .......... 270.0 2264 22-86 1193-5 lOC;*OO 99089 The numbers required by theory agree well with those furnished by experiment except in the case of the SO in which there is a deficiency of nearly one per cent. in the amount found. This may be accounted for by the occurrence of a small quantity of silicic acid in the mineral.The formula of the mineral after it has been dried at 100’ C. is-2Cu”S0,.5Cu’’H2O2 .4A1”/H303. This formula demands these percentages- YOL. x1x. L 134 CBURCH ON KEW AXD RARE CORXISH 31INEltALS. Theory. Experiment. (mean.) 7 cuo .......... 553.5 49.65 48-85 2 AI,O ......... 206.0 18-39 18-33 2 so .......... 1RO*O 14% 13.43 11 H,O .......... 198.0 17-68 18.10 1121.5 100*00 98.71 This new mineral though physically and chemically distinct from Lettsomite is near that species. Woodwardite is more basic than Lettsomite both in regard to the cupric and aluminic oxides. The difference is most strikingly seen in the percentage of alumina; in Lettsomite this amounts to 11.06 per cent. only according to Dr. Percy's analysis in Woodwardite it is nearly 18 per cent.It is possible to regard the new mineral as a compound of Ero-chantite and gibbsite. A trace of copper is removed from Woodwardite by digestion in cold water. Analysis IV. was made with a specimen so purified. The following percentages are those deduced from analyses I. II.,IV. V. and VI. Before calculating the results the small amount of silica found about 1 per cent. has been subtracted in all the analyses but 11. In analysis I. the phosphoric acid which was found in the alurniua has also been deducted -03 of a grain of Mg','P,O was obtained corresponding to -0192of P,O :-Analysis of Woodwardite dried in vucuo :-I. 11. IT. v. VI. H,O lost at 100'. ..... 5-28 5.69 5-53 3'H0} 23.65{16.79 -I c H,O lost on ignition .. CUO ................ 46-80 -46.95 - Ai,O .............. 17.93 -17.40 - SO ................ 12.54 12.37 12.60 - The following percentages are based on analyses I. III. and IV. the weights taken being those of the miueral dried till con- stant at 100"C. Analyses of TVoodwardite dried at 100"C :-I. 1x1. IV. H,O lost on ignition. ... CuO ................ (1965) 48-67 18.48 48.34 17.72 49.54 Al,O,. ............... SO ................ 18.64 13.04 17.97 13.95 -.- 18.37 13-30 100.00 98.74 98.93 CHAPMAN ON THE ACTION OF NITROUS ACID ETC. 135 I have already described to the Society several mineral species new to science as occurring in Cornwall. During my experiments I have ohtained numerous results relating to species already de- scribed some of which however have not hitherto been recognized as Cornish or are of rare occurrence.MeZuconite.-This mineral vas described by me in March last as occurring in a definite crystallized form I had then observed forms quite incompatible with the cubical system and had com-municated the fact to Professor Miller of Cambridge in my notice in the Chemical News I stated that it was my intention to measure the crystals but Professor Maskelyue soon after read a paper on the crystalline form of the mineral before the British Association last summer and exhausted the subject although the paper has not yet been published in full. I cannot regret that the crystallographic work has fallen into hands so much more competent to deal with it than my own.Murrnatite. -This black variety of blende occurs in Cornwall. The composition is similar to the Marmato specimen analysed by Boussingault and is represented by the expression 4ZnS.FeS. Erinite and CornwalZite.-The only reported locality of erinite is Limerick. But I:have a few grains which I have identified with this species from Cornwall. I have met more frequently with Cornwallite a perfectly distinct species. But there exists an im-pure chrysocolla containing phosphate which has occasionally been mistaken for the latter species. Autunite.-I have examined a Cornish specimen of autunite incrusting chalcolite and found it as free from copper as the St. Symphorien specimens.

ISSN:0368-1769    

DOI:10.1039/JS8661900130

出版商:RSC    

年代:1866

数据来源: RSC

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CHAPMAN ON THE ACTION OF NITROUS ACID ETC. 135 XIV.-Action of Nitrous Acid on Nuphthylamine. INtheir first paper on this subject," Rlessrs. Perkiii and Church state that by the action of nitrous acid on naphthylamine or rather by the action of a soluble nitrite on a salt of naphthylaminc a red btlse was obtained having the peculiar property of turning violet on * Quarterly Journal of Chemical Society vol. ix page 1 et 8ep. L2 CBAPMAN ON THE ACTION OF the addition of acids named by them azo-dinaphthyldiamine.They state that this substance is analogous to or identical with one obtained from dinitronaphthalene by the action of nascent hydrogen; and from an analysis of the former substance they were led to the formula C,,H,N,O. Were this formula correct the production of the compound in question by the action of nascent hydrogen on dinitronaphthalene would be intelligible ;but as they subsequently succeeded in obtaining this compound in a state of purity and as it was then found to possess the composition CzoH15N3*, it is by no means clear how such a compound could be formed in the manner above stated.And in fact I could not obtain any evidence of the substance by this method but on the contrary obtained a com-pound of a dark green colour possessing feeble basic properties ; it dissolves in alcohol forming a tolerably bright green solution. Alcohol acidified with hydrochloric acid dissolves much more of it but with a dirty olive-green colour. Ammonia precipitates it from this solution with its original colour.I could not make the coni- pound crystallise and have not further examined it. Messrs. Perki n and Church prepare azo-dinaphthyldiamine by acting on 2 eq. of naphthylamine with 1eq. of nitrous acid and effect this object by acting on 2 eq. of hydrochlorate of naphthyl-amine with 1 eq. of nitrite of potash and 1eq. of potash+-2(Cl0H9N.I-IC1)+ KNO + KHO = C,,Hl,N +2KC1+ 3H,O. The process answers admirably ;the only points needing attention are that the sohtion of hydrochlorate of naphthylarnine must be cold and dilute.$ The liquid is at once filled with a white precipitate which rapidly turns scarlet and gradually deposits. This is the substance in question; it has pnly to be filtered OF,washed with cold water and crystallised from alcohol; it is then in a state of perfect purity.I discovered this substance amongst the products of the action * Chem.SOC.J. [2] i 207. + Azo-dinaphthyldiamine ie not obtained by acting upon a mixture of 1 eq. of nnphthylarnine and 1eq. of hydrochlorate of naphthylamine dissolved in alcohol with 1 eq. of nitrite of potassium. If such a mixture be made the liquid yields no crystals on evaporation but a pitch-like substance gradually separates which dissolves in alcohol with violet colour turning red on addition of acids. The substance when quite cold shows faint signs of crystallisation. 5 This fact was kindly communicated to me by Prof. Church. XfTROUS ACID ON NAPETHYLAMINE. of zinc-ethyl on a mixture of nitro- and dinitro-naphthalene.The obseivation was accidentally made I supposed myself to be act- ing on pure dinitronaphthalene ;but on repeating the experiment 1 could not obtain the same result. As the dinitronaphthalene em- ployed in the first case had only been washed in boiling alcohol and not recrystallised I supposed that it might contain a small proportion of nitronaphthalene and that this substance might produce the base in question. As I knew from previous experiments that it was incapable of doing so alone I concluded that a mixture of the two was necessary to produce the base and found this conclusion to be borne out by experiment. At the time of making this obser- vation I was unaquainted with Messrs. Perkin and Church’s second paper and therefore supposed that I had a new substance in hand.Nascent hydrogen at least in the form of €I$ willsreduce dini tronaphthalene to ninaphthylamine C,,H8N20 and the same agent will reduce nitronaphthalene to naphthylamine C,,HgN. Now if these two substances were to unite and water were eliminated C2,H,,N (azo-dinaphthyldiamine),would be prod uced C,,H,N20 + C,,HgN = C2,H1,N3 + H20 And in fact on treating a mixture of dinitronaphthalene and nitronaphthalene in alcoholic solution with zinc and hydrochloric acid the splendid violet colour of azo-dinaphthyldiamine is produced. The colour of course very soon goes and is not produced for some time after the mixture is made. I intend to examine this reaction more fully. If instead of employing in the preparation of azo-dinaphthyldia- mine 1 eq.of nitrous acid to 2eq. of naphthylamine we take 1 eq. of each we still obtain the substance but in an impure state; and if some of this impure substance be dissolved in alcohol hydro- chloric acid added and then ether and tbe whole diluted with water the ether will rise to the surface coloured coppery-red the other portion of the liquid being violet. On separating and evapo- rating off the ether a brownish gummy residue remaius. On liberating the azo-dinaphthyldiamitie by means of ammonia it will be found that it now readily crystallises from alcohol which it would not do before this purification. As the gummy substance dissolved by this ether seemed to be formed only when nitrous acid was present in excess I proceeded to try if I could obtain it by mix-ing an acidified solution of hydrochlorate of naphthylamine with a solution of nitrite also acidulated ;under these circumstmces the liquids remained clear but a slight effervescence took place the gas liberated being apparently nitrogen; in the course of about ten CHAPMAN ON THE ACTION OF minutes the liquid began to get a little thick and a pitch-like sub-stance gradually separated gas being evolved during the whole process.If during the earlier stages of this process the liquid be filtered off and ammonia added or if before the black substance begins to separate ammonia be added azo-dinapht hyldiamine will be precipitated apparently in a state of great purity; at least it crystallises very easily.If instead of employing ammonia we employ an alcoholic solution of naphthylamine adding it drop by drop so long scs the white spot formed at first by its addition dis- appears we shall arrive at a point at which the addition of a drop of the iiaph thylamine solution will cause azo-dinaytithyldiamine to separate from the fluid. Potash and soda produce a reddish-brown precipitate altogether devoid of basic properties. This substance if filtered off washed first with very dilute hydrochloric acid then with water and dried at 100' C. forms a chocolate-coloured powder. It is odour-less arid tasteless altogether insoluble in water hot or cold very slightly soluble in alcohol slightly more so in ether but very readily in bisulphide of carbon; benzole also dissolves it pretty freely butit would not crystalhe from any of these liquids.It dissolves in concentrated sulphuric acid with a green colour but regains its original colour on dilution and is precipitated apparently un-altered. Concentrated nitric acid also dissolves it but at the same time alters its composition. The colour of its alcoholic solution is not in the slightest degree affected by acids and it forms no compounds so far as I am aware with acids or bases or in fact with any class of substances whatsoever. Acted upon by nascent hydrogen it was rapidly decolorised. Heated on the platinum- knife it melts gives off a little red fume and leaves a very diffi-cultly combustible carbonaceous residue ; it was analysed by burning it ixi a stream of common air.It gave the following numbers- Substance. coz. H,O. Anal. I. . . . . -0535 gave 01612 and -0290 , 11. . . *0914 -2748 *0395 , 111. . . -1590 *4789 *0708 Or :-C. H. Anal. I... . . . 82.17 per cent. and 6-02 per cent. , 11. .. .. 81.99 , , >, 4-80 ,> , 111.. . . . 82.15 , >> 4.95 9 NITROUS ACID ON NAPHTHYLAMINE. 1\79 Two nitrogen determinations by D utn as' method gave the following results :-Substance. Nitrogen. Bar. Temp. Nit. p.c. Anal. I. . . -495 31.1 C.C. 760 O* 7*88 , 11... -283 18-96 C.C. 760 0. 7.98 From these numbers excluding the hydrogen in the first analysis I obtained the following average percentages :-C. H. N. 0. (by diff.) 82.1 4.87 7-93 5-10 but could not obtain a satisfactory formula.Of course as there is sufficient hydrochloric acid present to saturate both the naphthylamine and the potash of the nitrite the reaction really takes place on hydrochlorate of naphthylamine and not on naphthylamine itself. It is possible therefore that the nitrous acid effects changes in the naphthylamine-salt without completely breaking it up and that it is the addition of the alkali which completes the reaction. The liquid filtered off after the deposit of the brown substance contained no organic matter. The black substance before-mentioned as being formed when a solution of hydrochlorate of naphthyiamine is allowed to stand with an excess of nitrite of potassium and hydrochloric acid is like the brown substance uncrystallisable and soluble only with great difficultyin alcohol ether or bisulphide of carbon.It forms a yellow solution. It is soluble to a considerable extent in alcoholic ammonia. This solution is brown and the substance is precipitated from it apparently unchanged by the addition of acids. It will not bear a temperature of 100' without undergoing partial decomposition. If heated to a 100' for a considerahle time it partially melts and gives off gas; after this it becomes hard again and is fouiid to have lost about 6 per cent. of its weight. I could obtain no compound with it whatsoever. Its solution is easily decolorised by nascent hydrogen. Sulphurous acid has no effect upon it. Chlorine also seems to be without action at least in the cold.Sulphuric acid dissolves it without evolution of gas but it is not re-precipitated in an unchanged form on dilution. Concentrated nitric acid also dissolves it with-out evolutionof gas. It cannot be formed by the action of nitrous 140 ACTION OF NITROUS ACID ON NAPHTHYLAMINE. acid on the brown substance. Analysis of the substance furnished the following numbers :-Substance. COS H'O. Anal. I. .... *2305 gave -522 and 00615 , 11 .... *l225 02765 00325 Nitrogen determination :-Substance taken 01375gave 185 c. c. of N. at 767 bar. and 15' C. or :-Anal. I. gives 61.8 per cent. C. and 3-06 per cent. H. ,Y 9 JJ ) 11. , 61-6 2.95 , and the nitrogen determination gives 15.84per cent. From the foregoing numbers I deduce the following formula C,OH,fAO5~ Theory.Found. Average. C, ...... 62.18 '61.8 61.6 -' 61-70 €Ilo...... 2.59 3.06 2.95 -3-00 N ...... 14.51 -15.84 15-84 0 ...... 20.72 --39.46 (by dif.) 1ooooo 100*00 The following equation will show the formation of the substance from naphthylamine :-2CloH9N+6HN0 = C,0H,oN405+7HQO4-4N. Hydriodate of monoethylated naphthylamine when acted upon by a nitrite or by nitrous acid apparently produces the same compounds that a salt of naphthylamine does. At least on dissolving 2 eqs. of the hydriodate in water alid adding 1 eq. nitrite of potash mixed with 1 eq. potash a base having all the characteristics of azo-dinaphthyldiamine was precipitated. This substance differs tot ally from inonoeth ylated azo- dinap hthyldia- mine inasmuch as the latter base dissolves with violet colour in alcohol and is turned crimson by the addition of acids while the former dissolves with an orange colour which is turned violet by acids.

ISSN:0368-1769    

DOI:10.1039/JS8661900135

出版商:RSC    

年代:1866

数据来源: RSC

摘要:

141 XV.-On Magnesium WANKLYN By J. ALFRED and ERNESTT. CHAPMAN. THEmagnesium met with in commerce appears to be very pure as is shown by the following determinations of the quantity of hydrogen evolved on dissolving a known weight of the metal in dilute acids. The magnesiumsibbon such as is sold for exhibit-ing the magnesium-light was employed having been first rubbed bright with sand paper. I.-0*1275 grrn. of magnesium ribbon was dissolved in dilute acetic acid and the hydrogen evolved measured- Observed volume of gas ...... 127 cub. cent. (moist) Temperature .............. 11.2' C. Barometer ................ 754.8 millirnetres Height of water column iii the tube containing the gas cor- responding to 0.8 millimetres of mercury. Tension of aqueous vapour at 11.2"C.= 9.8 mm. Correction of the barometric reading i. e. for reduction for tem-perature = -1.0 millimetre. From this we deihice- Hydrogen = 127 cub. cent. (dryj at 11.2' C. and 743.2 millimetres pressure. = 115.31 C.C. (dry) at Oo C. and 760 m.m. pres-sure = -010665grm. (the weight of 1,000 C.C. of hydrogen at normal temperature and pressure being taken at -08939 grm.) Taking 12for the equivalent of magnesium this will correspond to 0.127980 grm. of real magnesium. Therefore 100 parts of magnesium-ribbon contain 100*38 parts of real magnesium. 11.-0*1410 grm. of magnesium-ribbon was dissolved in dilute hydrochloric acid and the hydrogen evolved measured-Observed volume of gas ........ 141 cub. cent. Temperature.................. 11.2' C. VOL. x1x. Y 142 WANKLYN AND CHAPMm Ox' MAGNESIUN. Barometer.. ................. 754.8 mm. Height of water column in milli-metres of mercury. ........... =0*8mm. Tension of aqueous vapour at 11.2"C. =9.8mm. Correction of barometer ........ = 1 mm. From which we deduce- Hydrogen = 141 cubic centimeters (dry) at 11.2" C. and 743.2 m. m. pressure. = 132.46 C.C. (dry) at 0" C. and 760 m.m. pres-sure = OgO11841grm. which corresponds to *142092grm. of real magnesium. Therefore 100 parts of magnesium-ribbon contain 100*78parts of real magnesium. IIT.-0*1340 grm. of magnesium-ribbon was dissolved in dilute sulphuric acid and the hydrogen evolved measured- Observed vol. of gas.. ..............133.2C.C. Temperature.. .................... 1l0 C. Barometer. ....................... 754.8 mm. Height of water column in mercury .. 1.1 mm. Teneion of aqueous vapour at 1l0 C. .. 9.8 mm. Correction of barometer ............ 1 mm. From which we deduce- Hydrogen = 133.2 C.C. (dry) at 11" C. and 742-9 m.m. pressure = 125.16 C.C. (dry) 0'at C. and 760 m.m. pressure = 0.011185 grm. which corresponds to ,134256 grm. of real magnesium. Therefore 100 parts of magnesium-ribbon contain 100*19 parts of real magnesium. The apparatus employed in these determinations was very simple. A small vessel such as is made for determinations of carbonic acid was used for the generation of the hydrogen (see fig.). The upper part of the vessel contaiued the dilute acid the lower portion below the glass stop-cock contained water and the WANKLYN AND CHAPMAN ON XAGNESIUM:.14!3 weighed magnesium-ribbon. The method of using the apparatus together with the fact that accurate measurements of hydrogen I I d-7-can be made over water saturated with atmospheric air will be familiar to those who are conversant with the ordinary processes of gas-analysis. It will moreover be obvious that instead of employing the pneumatic trough as we did it is quite practicable to use the merciirial trough. We are however of opinion that in this particular instance there would be no advantage in doing so. When it is considered that next to lithium the metal which has the lowest equivalent is magnesium it will be obvious that this determination of the percentage of metallic magnesium from the quantity of hydrogen gas liberated is an extremely rigorous pro- ceeding.Moreover the determinations may be made with great facility and are susceptible of a very high degree of precision. Indeed this measurement of the hydrogen evolred when the metal is dissolved in a dilute acid offers such advantages that we propose to determine equivalents by meam of it believing that with suitable precautions it will be found to rival in accuracy the met,hods hitherto employed . M2 144 WANKLYN AND CHAPXAN ON MAQNESIUM. We have made some observations on the chemical properties of metallic magnesium which appear to be of interest.Towards the halogens this metal is very indifferent. At ordinary tempera- tures a solution of iodine in alcohol or ether has very little action on it and even at 100"C. a solution of iodine in iodide of methyl is only very slowly decolorised by it. Magnesium may be dipped into liquid bromine without being attacked and when plunged into chlorine gas it is not immediately tarnished. This inertness of magnesium would seem to be con-nected with the well-known decomposition of its haloid salts when their aqueous solutions are evaporated to dryness. With mercury it forms an amalgam endowed with very singular properties. To obtain this amalgam magnesium is heated with mercury nearly to the boiling point of the latter whereupon com- bination takes place attended with very violent action somewhat like that between mercury and sodium.An amalgam of magne-sium containing only one part by weight of magnesium to two hundred parts of mercury tarnishes instantly on exposure to the air swells up and becomes very hot when just moistened with water and decomposes water violently when immersed in it. A comparison was made between sodium-amalgam and magnesium- amalgam. The magnesium-amalgam which has just been described containing one part of magnesium to two hundred parts of mer-cury decomposed water far more rapidly than a sodium-amalgam containing the same proportion or even twice as much sodium. It is worthy of note that whilst amalgamation diminishes the energy of sodium it increases the energy of magnesium.The foregoing observations are for the most part in accordance with the results obtained by Dr. Phipson who has shown that iodine may be distilled from magnesium without attacking the metal and that magnesium alloys. with tin forming with it au alloy capable of decomposing water. It would seem that magnesium has a great tendency to form these alloys capable of decomposing water. Dr. Phipson's observation that mercury does not amalgamate with magnesium in the cold depends most probably on his not having polished the magnesium. When perfectly clean magnesium combines slowly with mercury even in the cold. Dr. Phipson's paper Proc. Roy. SOC.xiii 217 contains no account of the amalgam of magnesium. The experiments above described were made in the Laboratory of the London Institution.

ISSN:0368-1769    

DOI:10.1039/JS8661900141

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年代:1866

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145 XVL-A Further Contribution to the History of the Pe~odidesof the Organic Bases. By WILLIAM A. TILDEN. SOMEtime ago in a paper which I had the honour of submitting to the Chemical Society I described several compounds similar to others already known which result from the union of iodine with the hydriodates of the several organic bases from which they are derived. Since that time I have made a few experiments upon some substances which I have found to possess a similar consti- tution containing however chlorine in place of two atoms of the iodine. These chloriodides have not perhaps quite the same interest that attaches to the corresponding iodides since all that I have examined appear to be destitute of the peculiar action upon light so remarkable in several of those bodies.They are produced simply by adding aqueous protochloride of iodine to an acid aqueous solu- tion in water of the hydrochlorate of any of the bases. A yellow precipitate is obtained which speedily becomes crystalline. Some few admit of recrystallisation from dilute hydrochloric acid but the majority upon attempting resolution are either entirely broken up with the formation of products of oxidation or deposit upon cooling oily substances with which it was not thought worth while to attempt anything further. The highly complex natural alkaloids all appear to furnish pre- cipitates of the same nature which are distinctly crystalline under the microscope; but I thought it would be more satisfactory to examine in detail the compound produced from one of the arti- ficial bases of known constitution.Chloride of Tetrethylammonium whose iodide unites with two extra atoms of iodine producing a teriodide which is crystalline and definite was dissolved in dilute hydrochloric acid the solu- tion gently heated and a quantity of aqueous protochloride of iodine added. Upon standing large fern-leaf crystals belonging to the regular system were deposited. They were dried in vacuo and analysed. I. *4837gramme gave- W05 g':amme of mixed iodide and chloride of silver Theo- TILDEN ON THE PERIODIDES retically the precipitate should have weighed *7695 gramme. 11. 05347 gramme gave- *1612metallic platinum. 111. 05763gramme gave- *0935metallic palladium corresponding to *2228iodine.These results give percentages coinciding with those required by the formula (C,H,),NCl,I. Experiment. Theory. N ........ 4.264 4.268 I.......... 38.66 38-71 This compound is more soluble in dilute hydrochloric acid than in water which latter causes decomposition. The solution gives reactions precisely resembling those of protochloride of iodine itself. Iodine is liberated from iodide of potassium proto-salts of iron converted into persalts and on addition of iinc to the liquid it slowly dissolves at first precipitating iodine which after a time disappears. Baryta or lime-water added to the solution drop by drop likewise causes a liberation of iodine which mbse- quently vanishes on adding an excess of the reagent.These changes are sufficient to show that the constitution of this body iq represented by the formula I ascribe to it. Hydrochlorate of triethylamine yields in like manner a com- pound crystallising in fine needles but it is so unstable that it could scarcely be obtained in a fit state for analysis. The most easily manageable of these substances I found to be that con-taining caffeine which furnishes crystals apparently oblique rhombic prisms with the utmost readiness. A quantity of these was dried in vaciio and submitted to analysis. I. -3797 gramme gave 05018gramme of mixed iodide and chloride of silver; by calculatiou this should have been 05043gramme. 11. 07945 dissolved in aqueous iodide of potassium required a quanty of hyposulphite solution equivalent to -51197 iodine.Half of this -255'38 corresponds to chlorine -0715 gramme. OF THE ORGHIC BASES. 111. *7177 gramme gave -1920H,O -6455CO,. These numbers agree closely with those required by the formula (C,HloN,O,H)Cl,I as shown below. Experiment. Theory. C .......... 2452 24.45 H.......... 2.96 2.79 I .......... 32.20 32-31 Cl.. ........ 8-99 9-03 -7 -Total C1 .... -18.06 Quinine like the rest gives a yellow precipitate which in this case may be obtained in distinct crystals from dilute hydrochloric acid not however without becoming much darkened in colour. Its solution gives the reactions already described. These iodides and chloro-iodides naturally appear to be related to the substances formed by the solution of iodine in iodide of potassium of sodium and of ammonium which may fairly be con-sidered as having a similar constitution.Obviously they may all be viewed as constructed either on the type of the triple molecule of hydriodic acid when the metal would be represented as triatomic :-Periodide of Potassium. ....... KT , Ammonium ...... (NH4)”’13 , Tetrethylammonium {N(c2H5)41”’13 Chlorhdide of >> ”2HJ41”qI , Caff-ammonium .. (C,HloN,O,H)’”C1,I or they may be considered as derived from the double molecule of hydrochloric or hydriodic acid in which case they would be written :-Periodide of Potassium. ......... K’IJI , Ammonium ........ NH4’I.II Chloriodide of Tetrethylammonium { (C,H,),N) 1C1.ClT

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DOI:10.1039/JS8661900145

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年代:1866

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148 SPILLER ON THE ESTIMATION OF PROSPHORUS XVII.-On the Estimation of Phosphorus in Iron and Steel. By JOHNSPILLER, F.C.S. IN the course of a somewhat extensive series of analytical exami- nations which are now being made upon iron and steel under the direction of the Chemist of the War Department it has become possible to introduce a modification into the process ordinarily employed in the estimation of phosphorus whereby a saving of time is effected without impairing the accuracy of the results. The method of procedure hitherto followed has been that de- scribed by Fresenius in which the nitro-hydrochloric solution of the metal is for the most part reduced to the state o€ proto-salt by the action of sulphurous acid. The excess of the latter having been expelled by boiling the solution is cooled partially neutralized with ammonia and boiled with acetate of ammonia whereby all the phosphoric acid is concentrated in the precipitate of basic ferric acetate so formed whilst the greater portion of the iron remains dissolved as ferrous acetate and can be separated by filtration.The mixture of pbosphate and basic acetate of iron remaining on the filter is then slightly washed dissolved in hydro- chloric acid and to the warm solution are added successively citric acid ammonia in excess and sulphide of ammonium whereby the iron is precipitated and niay be filtered off washed perfectly with sulphide of ammonium water and the solution only reserved. For the extraction of the phosphoric acid the bulky filtrate is slowly evaporated with full exposure to air the sepalmated sulphur removed and the solution precipitated as usual by the mixed chlorides of magnesium and ammonium in the presence of free ammonia.The product is then incinerated and weighed in the form of pprophosphate of magnesia. The modification of the process to which reference is now to be made consists in dispensing altogether with the acetic treatment. For the purpose of concentrating the whole of the phosphoric acid contained in the solution of the specimen under examination in a comparatively small proportion of the ferric oxide it is only necessary to add to the partially reduced and cold solution aqueous sesqui-carbonate of ammonia until the precipitate at first red assumes a greenish hue-a sign that some of the ferrous carbonate is also thrown dorm.The whole of the phosphorus is contained IN IRON AND STEEL. in the precipitate thus obtained and this fact admits of easy proof for it is only necessary to add to the filtrate a few drops of ferric chloride and agaiii the requisite amount of carbonate of ammonia to procure a further precipitate which can be separately examined. Not only has this been done in several trials the results of which will presently be described but the filtrates have been afterwards tested by the acetic process which has failed to detect any phos- phori'c acid in the solution. It has moreover been found unne-cessary to pay particular attention to the thorough expulsion of the excess of sulphurous acid before proceeding to the use of the alkaline carbon ate.A few precautions remain however to be noticed; firstly the temperature at which the precipitation (with carbonate of ammonia) should be conducted. The liquid must not be heated above 70° or at most 75" Fahr. otherwise a loss of phosphate will be experi- enced as the following numbers will show :-Temperature. Phosphorus per cent. obtained by Deg. Fahr. 1st Pptn. 2nd Pptn. 70 *lo3 Nil. 100 *146 *004 100 -258 0006 150 *238 *022 The experiment last quoted was an extreme case both as regards temperature and the presence of sulphiirous acid the excess of which mas not boiled off before adding the carbonate. Secorldly after having dissolved the metallic iron in red nitro-hydrochloric acid it is advisable to drop into the flask containing the solution a few small pieces of solid carbonate of ammonia which by causing an effervescence in the liquid will aid in the expulsion of nitrous vapours.The great excess of acid should now be driven off by evaporation and the diluted solution further neutralized with ammonia or the carhonate before adding the bisulphite of ammonia to effect the reduction of the ferric chloride. The general accordance of the results obtained in experiments made upon several samples of wrought iron taken from the deliveries of three manufacturers will appear from the following tabulated statement :-Series. Phosphorus per cent. found. I. *038 0048 *034 11. -115 *110 -108 111. 260 -264 -273 CHAP?\IAN ON MERCURY-ETHYL. And finally the results obtained in the analysis of identical samples of wrought-irou by the carbonate (a),and by the acetate method (p),are shown in two columns as under. Phosphorus per cent. a. 8. A. '034 -036 B. -048 0043 C. 0103 *108* D. E. L-150 *160 The application of the above process to the analysis of steel does not call for any special remark but when cast-iron containing much silicium is operated upon it mill always be necessary to search for and separate any silica that may be contained in the ultimate product.

ISSN:0368-1769    

DOI:10.1039/JS8661900148

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年代:1866

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CHAP?\IAN ON MERCURY-ETHYL. XVIII.-bTote on Mercury-ethyl. By E. T. CHAPMAN. BROMIDE of ethyl may be made to yield mercury-ethyl by the action of dilute sodium-amalgam in the presence of acetic ether just as the iodide yields it. The reaction takes place equally well with both substances. The compound was recognised by the action of iodine upon it anti also by converting it into zinc-ethyl by digestion with metallic zinc. This is I believe the first instance of an organo-metallic compound of an alcohol-radical being produced from any other source than the iodide. I failed in obtaining zinc-ethyl by the actioii of metallic zinc on bromide of ethyl. Nevertheless bromide of zinc is formed and ga3 svolved. The presence of mercury greatly-facilitates the reaction. I may also mention that sodium decomposes alcoholic solutions both of mercury-ethyl and mercury-methyl liberating mercury. The sodium first floats on the solution but rapidly becomes amalgamated and sinks to the bottom evolving much gas during the process and finally leaving a globule of mercury. These experiments were made in the Laboratory of the London Institution. * Mean of two experimcnts-'l04 and *112.

ISSN:0368-1769    

DOI:10.1039/JS8661900150

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年代:1866

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151 XIX.-A Modijication of Berthelot’s Experiment for the Formation of Acetylene by imperfect combustion. By HERBERT MCLEOD. INJanuary last* M. Berthelot described an experiment in which he formed acetylene by the cornbustion with an insufficient quantity of air of bodies containing carbon and hydrogen. He found that not only did hydrocarbons produce this result but that compounds containing oxygen in addition such as ether or chlorine such as ethylic chloride gave rise to the formation of considerable quantities of acetylene. An experiment of this kind he describes as follows :-“ Let us fill an eprouvette of 300 cubic centimeters’ capacity with the gas or pour into it a few drops of the volatile liquid ; and then add a few cubic centimeters of am- moniacal cuprous chloride inflame the combustible vapour and ineline the eprouvet te almost horizontally causing it to revolve so as to spread the cuprous reagent over the whole interior surface ; we see immediately the cuprous acetylide produced.It is gene-rated in contact with the flame and below in the form of a characteristic red precipitate. ‘‘ The experiment is particularly brilliant with ordinary ether and hydride of amyl. It is a beautiful lecture experiment. The quantity of acetylene which manifests itself under these circumstances in the form of acetylide is evidently greater than that which is produced under the influence of heat alone acting upon the same compounds. The quantity of acetylene really produced is besides much superior to that which becomes mani- fest in the form of acetylide because the greater part of the acetylene burns almost immediately after being formed and with- out coming in contact with the reagent.Also I think that it will be possible to deduce from this experiment conveniently modified a method of preparation of acetylene more advantageous than those which are known up to the present time.” It is the object of this communication to describe such a modification. It is obvious that the most favourable condition for obtaining an imperfect combustion is when the combustion is so to speak inverted aud oxygen is made to burn in an excess of the carboni- ferous gas or vapour. For this purpose an apparatus was em- * Compt. Rend. lxii 94. 152 MCLEOD ON THE FORMATION OF ACETYLENE ployed which had been originally constructed some few years ago for exhibiting the combustion of oxygen in ammonia as an illus- tration in Dr.Hofmann’s course of lectures and which was used for various similar experiments such as the combustion of oxygen in hydrogen of oxygen in coal gas and of chlorine in bydrogen. The apparatus arranged for the formation of acety-lene is shown in Fig. 1. The experiment is most conclusively performed by burning oxygen in marsh-gas which is passed from a gas-holder through the tube a into a test tube A. When the air has been expelled a quantity of solution of cuprous chloride is poured into the test-tube through the tube b and subsequently an excess of ammonia the tube being then closed by a compression-cock.The presence of any acetylene in the gas would here be indicated by the formation of the characteristic red precipitate. The gas theii pneses into a vertical cylinder R closed at the lower BY IMPERFECT COMBUSTION. extremity by a perforated cork carrying two tubes one of which is rather wide; this tube is closed with a conical cork carrying a piece of quill tube to the top of which a platinum jet is adapted by rolling a piece of thin platinum foil into the form of a tribe of two or three millimetres in diameter and placing it within the glass tube and subsequently fusing the glass in contact with the platinum ;the lower extremity of the glass tube is connected with a gas-holder containing oxygen. The arrangement of the lower part of this cylinder is shown in Fig.2. From the cylinder B the gases pass into a small receiver and from thence into a bottle D fitted with a cork and tubes perfectly similar to the fit-tings of the test-tube A. When the air has been expelled from the whole apparatus the solutions of cuyrous chloride and ammonia 'IC.2 are introduced into D through the tube d which is afterwards closed. To ignite the oxygen in the marsh-gas the conical cork and jet are removed from the wide tube c > a current of oxygen allowed to pass through the jet the marsh-gas escaping at c inflamed the jet passed through the flame and the cork rapidly returned to its place. The oxygen then continues burning in the marsh-gas and in the course of a few seconds the production of acetylene is indicated by the formation of the red precipitate in the bottle D.By this process it is easy to obtain from marsh gas about 1.5 grammes of cuprous acetylide in an hour. By employing the gases in larger quantities it will doubtless be possible to increase this amount of product considerably. For the purpose of pre-paring acetylene one would of course employ ordinary coal gas perhaps charged with ether vayour the tube A being dispensed with; and if the oxygen can be replaced by atmospheric air an experiment which will be tried shortly the product!on of this interesting hydrocarbon will become a matter of comparative ease,* and although the gas may not be obtained so rapidly or in such a state of purity as by other methods yet the simplicity of the process and the ease with which the necessary materials are pro-cured appear to indicate it as one of the most convenient hitherto suggested. It is quite possible and even probable that M. Ber-* Since writing the above it has been found poesihle to replace the oxygen by atmospheric air and with satisfactory resalts. KOPP ON THE SPECIFIC HEAT thelot has already modified his experiment in the manner above described but as far as I am aware no account of it has yet been published.

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DOI:10.1039/JS8661900151

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年代:1866

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154 KOPP ON THE SPECIFIC HEAT XX.-lnuestigutions of the XpeciJic Heat of Solid Bodies. By HERMANN KOPP. (Abstract from the Philosophical Transactions for 1865.) I. Historicat Introduction. 1. ABOUTthe year 1780 it was distinctly proved that the same weights of different bodies require unequal quantities of heat to raise them through the same temperature or give out unequal quantities of heat on cooling through the same number of ther-mometric degrees. It was recognised that for different bodies the unequal quantities of heat by which the same weights of different bodies are heated through the same range must be determined as special constants and considered as characteristic of the individual bodies. This newly discovered property of bodies Wil ke desig- nated as their specific heat while Crawford described it as the cornparalive heat or as the capaciiy of bodies for heat.I will not enter upon the earliest iiivestigations of Black Irvine Craw-ford and Wilke with reference to which it may merely be men- tioned that they depend essential17 on the thermal action produced when bodies of different temperatures are mixed and that Irvine appears to have been the first to statc definitely and correctly in what manner this thermal action (that is the temperature result- ing from the mixture) depends on the original temperature the weights and the specific heats of the hodies used for the mixture. Lavoisier and’laplace soon introduced the use of the ice- calorimeter as a method for determining the specific heat of bodies and J.T. Mayer showed subsequently that this determination can be based on the observation of the times in which different bodies placed under comparable conditions cool to the same extent by radiation. The knowledge of the specific heats of solid and liquid bodies gained during the last century and in the first sixteen years of the present one by these various methods may be left unmen- tioned. The individual determinations then made were not suffi-ciently accurate to be compared with the present ones nor was any general conclusion drawn with reference to the specific heats of the varions bodies. OF SOLID RODIEB. 2.Dulong and Petit's invatigations. the publication of which commenced in 1818. brought into the field more accurate deter- Berzelius's Regnault's weights.weights. weights. .tomic weights . hermal atomic rsual equivalen aodern atomic .... Aluminium .. A1 = 13.7 A1 = 13.7 A1 = 13.7 A1 = 27.4 Antimony .... Arsenic ...... Barium ...... Sb = 61 AS = 37.5 Ba = 685 8b = 61 AS] = 37.5 Ra = 68.5 Sb =122 AS = 75 Ba = 68.5 Sb =122 Ag =75 %a =137 Bismuth .... Bi -105 Bi =lo5 Bi =210 Bi =210 Boron ...... B = 10.9 B = 10.9 B = 10.9 B = 10.9 Bromine .... Br = 40 Br = 40 Br = 80 Br =80 Cadmium .... Cd = 56 Cd = 56 C'd = 56 @d =112 Calcium ...... Ca = 20 Ca = 20 Ca = 20 6a =40 Carbon ...... Chlorine .... C=6 Cl = 17.75 c C1 = = 32 17-75 C=6c1 = 35.5 E c1 =12 = 35.5 Chromium.... Cobalt ...... Fluorine .... Copper ...... Cr = 26.1 CO = 29.4 CU = 31.7 F1 = 9.5 Cr = 26.1 CO = 29.4 CU = 31.7 Fl = 9.5 Cr = 26.1 CO = 29.4 CU = 31.7 F1 = 19 Qr = 52.2 60= 58.8GU = 63.4 F1 =19 Gold ........AU = 98.5 AU = 98.5 AU =197 AU =197 lodine ...... Hydrogen .... H I = 0.5 = 63.5 I = 63.3 H= 1 I =127 H= 1 I =127 Iridium ...... Ir = 99 Jr = 99 Ir = 99 €r =198 Iron ........ Fe = 28 Fe = 28 Fe = 28 Fe =56 Lead ........ Pb =103*5 Pb =103*5 Pb =103. 5 Pb =207 Lithium ...... Li = 7 Li = 3.5 Li = 7 Li =7 Magnesium .. Manganese .. Mercury ...... Molybdenum.. Nickel ....... Nitrogen ..... Osmium...... Mg= 12 Mn= 27.5 Hg=lOOMo= 48 Ni = 29.4 N=7 OS = 99.6 Mn = 27.5big= 12 3ig =loo Mo= 48 Ni = 29.4 N *-7 0s 99.6 Mg= 12 MU = 27.5 Hg =lo0 MoL 48 Ni = 29.4 N = 14 08 = 99'6 %g= 24 mu= 55 sg =200 3€0= 96 Si = 58.8 N =14 8s =199*2 nr Oxygen ......Palladium. . . Phosphorus .. Platinum .... 0 = 8 Pd = 53.3 P = 15.5 Pt = 98.7 Pd P Pt = 53.3 = 15.5 = 98-7 0=8 Pd = 53.3 P = 31 Pt = 98.7 Q =16 Fd =106*6 Y = 31 4% =197.4 Potassium .... Rhodium .. . K = 391 Rh = 52.2 I( = 19.55 Rh = 52.2 I< = 39.1 Rh = 52.2 K = 39.1 8h =104*4 Rubidium .... Rb = 85.4 Rb = 85.4 Rb = 85.4 Selenium .... Se = 39.7 Se = 39.7 Se = 39.7 f3e = 79.4 Silicium .... Si = 21 Ei = 14 5i = 28 Silver ........ Sodium ...... Ag -108 Na = 23 Ag= 54 Na = 11.5 Na= 23Ag =1OS Na= 23Ag =108 Strontium .... Sr = 43.8 Sr = 43.8 Sr = 438 %r = 87.6 Tellurium .... Thallium .... Sulpliur ...... S Te Tl = 16 = 64 =204 S = 16 Te = 64 T1 -102 S Te Tl = 16 L= 64 =204 S Tin .......... Titanium .... Tiingsten .... Zinc ........ Sn Ti W Zn = 59 = 25 = 92 = 32.6 Sn = 59 Ti = 25 W = 92 Zn = 32.6 Sn = 59 Ti -25 W = 92 Zn = 32.6 En -65.2 W =184 Zirconium ....Zr = 33.6 Zr = 44.8 Zr = 89.6 IEOPP ON THE SPECIFIC HEAT minations and a general law. The investigations of the relations between the specific heats of the elements and their atomic weights date from this time and were afterwards followed by similar in- vestigations into the relations of the specific heats of compound bodies to their composition. In order to give a general view of the results of these investigations it is desirable to present for the elements mentioned in the sequel a synopsis of the atomic weights assumed at different times and of certain numbers which stand in the closest coanexion with these atomic weights. For each of the previous columns the relation of the numbers to each other is alone important and not the number which is taken as unit or starting-point.Berzelius’s atomic weights and Regnault’s thermal atomic weights are corrected with the nearest and most trustworthy experimental dete%minations without altera- tion of the bases for the adoption of these numbers. The nume- rical relations presented in the above Table require from the chemical point of view no further explanation. The relations of these numbers to the specific heat form the subject of the investi- gations which are presented in the sequel. 3. The experiments by which Dulong and Petit* showed in the case of mercury various solid metals and glass that the specific heat increases with increasing temperature were made by the method of mixtures.They determined at ordinary tempera- tiires the specific heats of a greater number of elements hy the method of cooling.? They found that when the numbers in the first column in $ 2 corresponding to the elements Bi PPb Au Pt Sn Zu Cu Ni Fe and S (the Berzelian atomic weights) are multiplied hy the respective specific heats of these bodies approxi- mately the same number is obtained ; and that approximately the same number is also obtained when 4Ag 4 Te and 3 Co are multiplied by their corresponding specific heats. They were of opinion that the atomic weights of the elements could and should be so selected that when multiplied by the specific heats they should give approximately the same number as product.This observation and this view which Dulong arid Petit stated in 1819 in the following manner The atoms of all simple bodies I‘ have all exactly the same capacity for heat,” have since that time been known as Dulong and Petit’s Law. I shall not here dwell upon Potter’s investigations on the specific heat of metals and on the validity of Dulong and Petit’s * Ann. Ch. Phys. [2] vii 142. t Ild. x 395. OF SOLID BODIES. law,* but proceed directly to discuss Ne umann’s investigations which rank worthily by the side of those of Dulong and Petit. 4. In his “Investigation on the specific heat of Minerals,” Neumann (in 1831) first publishedt more accurate determina- tions of the specific heats of solid compounds. He investigated a large number of such compounds especially those occurring in nature partly by the method of mixture and partly by the method of cooling; and he determined the sources of error in both these methods and the corrections necessary to be introduced.In a postscript of this paper he mentioned that he continued the in-vestigations with an apparatus which compared with that he had previously used promised far greater accuracy in the individual results without needing tedious and troublesome reductions. This apparatus by means of which the specific heats of solid bodies which may be heated in a closed space surrounded by steam can be determined with great accuracy he has not de-scribed.$ Of the general results of N eum ann’s investigations one must be particularly mentioned that a dimorphous substance has the same specific heat in its two conditions.This he showed was the case with arragonite and calcite and with iron pyrites and mar- casite. But the most important is the discovery that in analogous compounds the products of the atomic weights into the specific heats are approximately equal. Neumann stated this last ob- servation in the following manner :-(‘ In bodies of analogous chemical composition the specific heats are inversely as the stoYchiometrical quantities or what is the same stokhiometrical quantities of bodies of analogous chemical composition have the same specific capacity for heat.” Neumann adduced 8 carbo-nates 4 sulphates 4 siilphides (MeS) 5 oxides (MeO) and 3 oxides (Me,O,) as showing this regularity which is to be denoted as Neumann’s law.§ * Edinburgh Journal of Science new series vol.v p. 75 and vol. vi p. 166. J. F. W.Johnston’s remarks vol. v p. 278. I know these papers only from B e rz e 1 i u a’ s Jahresbericht vol. xii p. 17 and (x e hl e r ’a Physicalisches Worterbuch new edition vol. x,part 1 p. 805 et seq. t Pogg. Ann. xxiii 1. $ Pape (Pogg.Ann. cxx 337) has recently described this apparatus. I have had no opportunity of seeing Neumann’s memoir cited by Pape “Commentatio de emendenda formula per quam caIoret3 corporum specifici ex experimentis methodo mixtionis institutis computantur.” Regiomonti 1834. Q The objection of Regnault (Ann. Ch. Phys. [33 i 131) as to the inadequacy of the proofs adduced by Neumann in support of the law are not conclusive.VOL. XIX. h’ 158 EOPP ON TEE SPECIFIC HEAT 5. Soon after the publication of Neumann’s researches in 1833 Avogadro published* a “Memoir on the Specific Heat of Solid and Liquid Bodies.” He there gave a number of determi- nations of the specific heat of solid bodies made by the method of mixture. As far as can be ascertained by comparison with the most trustworthy of our newer determinations these results are by no means so accurate as those of Neumann; but they are far more accurate than those which had been obtained up to about 1830 and many of them come very close to the best of our modern results. It would be unjust to Avogadro’s determinationst to judge them all by oue case in which he obtained a totally erro- neous result (for ice by a modified method) ; and by the circum- stance that in a subsequent memoir$ he gives specific heats for several elements as deduced from -his experiments which are decidedly incorrect.$ Avogadro recognizes the validity of .hlong and Petit’s law.With reference to the specific heats of compound bodies he considers that he had established with tolerable probability that for solid and liquid bodies the same regularity prevails that he had previously deduced for gases from Dulong’s experiments That is (‘that the specific heat of‘ the atom of a compound body is equal to the square root of the integral or fractional number expressing the atoms or parts of atoms which go to form the atom of the compound body such as it exists in the solid or liquid state taking as unity the specific heat of the atom of a simple body in the same state.” He ob- serves that there is a difficulty incidental to the application of this law to solid and liquid bodies which is not met with in the case of gaseous bodies in which the composition by atoms or by volumes is held to be directly given by observation.This diffi-culty consists in knowing what constitution is to be assigned to the body in question for the solid or liquid condition; this con-stitution from the conclusions derived from his theoretical con- sideraticns would often be different from that which the body has Ann. Ch. Phys. [2] Iv. 80 as an abstract from Memorie della Societh Italiana delle 8cienze residente in Modem t.xx. Fascicolo 3 di fisica. .t. They are also found in Qmelin’s Handbuch der Chemie 4 Adage vol. i. in the Tables pp. 215-218 et. seq. (English Edition I 241-244 et.seq.) $. Ann. Ch. Phys [2J vol. lvii. p 113. 0 I know Avogadro’s investigations only from the abstracts published in the Annales de Chimie et de Physique and am not aware whether the bold correction8 of Avogadro urged by Regnault (Ann. Ch. Phys. [23 lxxiii 10) were used in all his experimenfs or only in some OF SOLID BODIES. in the state of gas or vapour. His considerations led him to assume the atomic weights of many elements different from those which Berzelius had given Avogadro described the atoms to which the weights assumed by him refer as thermaZ atoms.6. R. Hermann published in 1834 a memoir ‘‘ On the propor- tions in which Heat unites with the Chemical Elements and their Compounds and on the Combining Weights considered as quo-tients of the capacity for Heat of Bodies into their Specific Gravities”*. He gives there a great number of determinations of the specific heat of solid bodies (of a few elements but chiefly of compound bodies;. He made a few experiments in which he used Lavoisi er and Laplace’s calorimetert ; but by far the greater number of determinations are made by the method of cooling.$ Many of his results approach very closely to those which are at present considered accurate but a considerable num-ber among them are decidedly incorrect. As for Hermann’s theoretical results it must be borne in mind that regarding matter as he does not from the point of view of the atomic but of the dynamical theory he puts the idea of combination-weights in the place of the idea of atomic weights.The propositions which he endeavours to establish are the follow- ing :-The quotients obtained by dividing the specific gravities of the elements5 in the solid state by their specific gravities in the gaseous state are either equal or stand to each other in simple ratios; they are 1 2... . . . 15 times as much as a certain base. The same is the case with the products of the specific gravities of the solid elements into their epecific heats that is with their relative heat ; and the number indicating the multiple for a given element is the same for both the above relations.It follows from this that the combining weights m of the elements are proportional to the quotients of their relative heats into their specific gravities in the solid condition ; that the products of the specific heats and Nouveaux MBmoires de la SociM Imperiale des Naturalistes de MOSCOU, vol. iii p. 137. + Hermann tried to alter this apparatus so as to make it serve for measuring the change of volume which takes place when ice melts ;but he did not further follow this application of the modified apparatus. $ They are found not quite complete in Gmelin’s Handbuch der Chemie 4 Anflage in the Tables. pp. 215-218 et. seq. (English edition I 24‘1-244 et. seq.) 9 Hermann considers that the specific gravities of the elements in the state of gas or vapour are either obtained by observation or may be theoretically deduced by assuming that they are in the ratio of the combining weights.N2 160 KOPP ON TRE SPECIFIC ‘EIEAT the combining weights for different elements are equal to a con-stant and that from the known combining weight of an element its specific heat in the solid form may be calculated (it is equal to 0*375,where m is the combining weight of the substance in question m referred to oxygen = 1). For several elements (phosphorus tel- lurium cadmium and silver for instance) atomic weights are taken which differ from those of Berzelius. In the case of the sulphides the specific heats may be calculated from those of the constituents assuming that the specific heats of the elements in these compounds are the same as in the free state.The same holds good for several chlorides and for basic metallic oxides if the specific heats of chlorine and of oxygen as given by the above formula are taken as basis. But in acids a smaller specific heat must be taken for oxygen (one-half in several acids and null in phosphoric acid) ; and there are even compounds (cassiterite e.g. or arsenious acid) in which the same element is contained partly with the normal and partly with the modified specific heat*. For oxygen-salts it is to be assumed that hoth the acid and the base have the same specific heat as in the free state and hence the specific heat of one constituent (of the acid for instance) may be calculated if that of the salt and that of the other constituent (the base) is known; and it is also found that the specific heat of chromic acid in neutral and in acid chromate of lead is the same.This memoir of Hermann’s did not become much known. Unacquainted with it other philosophers have subsequently de- veloped independently similar opinions. 7. In 1835 Rudberg described a method,? which by ascer-tainiug the heat developed when salts are dissolved in water in experiments in which the proportion of the salt to the water was constant but the temperature of the salt varied should give a means of at once determining the specific heat of the salt and of the heat which was either absorbed or became free. Yet the numbers which he obtained from his experiments for the specific heat of solid salts are undoubtedly erroneous.* Hermann designates such compounds as hermaphrodites. He thinks that an acid and a base may have the mme composition and that they may form salts with each other. Cassiterite for instance he considers to be stannate of binoxide of tin. t Berzelius’s Jahresbericht vol. xv p. 63. Pogg. Ann. xxxv 474. OF SOLID BODIES. 161 Dumas* (in 1838) discussed the possibility of determining the apecific heat of organic bodies by the following process. A pla-tinum vessel containing the substance in question along with a thermometer is to be heated to 30" or 40° and then brought into a vessel provided with a second thermometer and containing water the temperature being about 5" or 6' lower than that of I the surrounding room.When the temperature has risen to the same extent above that of the room both thermometers are to be observed. f know no determinations made by this method. 8. In 1844 Regnault commenced the publication of a series of important investigations which he had made on specific heat. As they are generally known I map be more brief in enumerating the contents of the individual publications. In the first which he published Regnault developedi the reasons which led him to prefer the method of mixture to other processes for determining the specific heats of solid bodies; he described his mode of exe- cuting this method and published the results obtained for a great number of elements.In a second memoir$ he gave the specific heats of several metallic alloys containing metals in simple atomic ratios and of a great number of solid chemical compounds; and he published comprehensive experiments on the specific heat of carbon in its different conditions. The investigations announced in the first memoir5 on the specific heat of organic ccxnpunds as well as those promised in the second memoir11 on the specific heat of sulphur at different temperatures have not to my knowledge been published. But in a third mernoirB Regnault has investi- gated the difference in the specific heats of certain metals accord- ing as they are hardened or soft and also with reference to sulphur according as it is in the native crystallised form or has solidified a longer or shorter time after being melted; and he has more especially tried to impart greater certainty to the method of cool-ing.In his subsequent investigations however he has used only the method of mixture as being the more certain. These investi- gations** have given the specific heats of a large number of solid elements and also of individual compounds. * Dumas'a Thbse sur la question de l'action du calorique sur les corps organiques (Paris 1835) Ann. Ch. Pharm. xxviii 161. t Ann. Ch. Phys. [2] lxxiii 5. 2 Ann. Cli. Phys. [3] i 129. 8 Ibid. [2] lxxiii '71. II Ibid. [3] i 205. 7 bid. [3] ix 322. ** Ibid. [3] xxvi 261 & 268 ;xxxviii 129 ; xlvi 257 ;lxiii 5. Compt. rend. Iv 88'7. 162 KOPP ON TEE SPECIFIC HEAT By his investigations Regnaul t has removed some objections which seemed to affect Dulong aEd Petit’s law and has given a great number of new cases in which it applies.He considers* this law to be universally valid and discusses the reasons why for individual elements the specific heats found do not quite agree with the lam but only approximately. In his view the atomic weight of an element is to be so taken that it agrees with Dulong and Petit’s law. He took the atomic weight of silver and of the alkaline metals half as great and that of carbon twice as great as Berzelius had done. Yet with regard to selecting by means of the specific heat from among the numbers which the chemical investigations of an element has given as admissible that which is the correct one Regnault does not always express himself deci- dedly.In the case of carbont and of siliciumj he mentions the possibility of their disagreement with Dulong and Petit’s law. He proved the validity of Neumann’s law for a number of cases very considerably greater than that on which it had originally been based and he expressed it in a much more general form.§ ‘‘In all compounds of analogous atomic composition and similar che- mical constitutiou the specific heats are approximately inversely proportional to the atomic weights. Regnaul t designates the numbers agreeing with this law as thermal atomic weights. He has either determined them directly from the nrimbers found for the specific heats of the elements in the free state applying Dulong and Petit’s law or indirectly by ascertaining the specific heat of solid compounds assuming Neumann’s law; or finally (and only in a few cases) he has determined them by means of their probable analogies.These are the atomic weights given in the second column of the table in 0 2. With regard to the relations of the specific heats of solid com-pounds to those of their constituents Regnault has shown11 that with metallic alloys at a considerable distance from their melting points the specific heats may be calculated from those of their constituents in tolerable accordance with the experimental results assuming that the specific heats of the metals are the same in the alloys as in the free state. The investigation whether for true * Ann.Ch. Phye. [2] lxxiii 66 ;further [3] xxvi 261 and xlvi 257. Ibid. [3] i 205. But both before and after (Ibid. [2] lxxiii ’71. and [3] xxvi 263) Regnault inclined to the view that carbon with the equivalent=12 and the specific heat found for woodcharcorl must be considered as obeying Dulong and Petit’s law. $ Ibid. Ixiii 30. 3 Ibid. i 199 11 Ann. Ch. Phya [3] i 183. OF SOLID BODIES. chemical compounds there is a simple relation between their specific heats and those of their constituent elements Regnault has re- served* till the conclusion of his experiments on the specific heats of gaseous bodies.? To my knowledge he has published nothing for solid bodies. But in 1862 with reference to the relations which had been recognized between the specific heats and atomic weights of solid simple or compound bodies he spoke as follows.$ ‘I It is true that these laws in the case of solid bodies apply only approximately to simple bodies and those compounds of least com- plex constitution; for all others it is impossible to pronounce any-thing in thia respect.” From some remarks of Regnault with reference to carbong and silicium,il he considers it possible or probable that the specific heat of certain elements in their compounds is different from that which they possess in the free state.9. In 1840De la Rive and Marcet publishedv investigations on the specific heat of solid bodies. They made their determinations by the method of cooling. They found that assuming Berzelius’s atomic weights selenium molybdennm and wolfram fall under Dulong and Petit’s law which they consider as universally valid ; but that carbon forms an exception and they consider it as pro-bable that its true atomic weight has not yet been ascertained.For several sulphides they found a greater specific heat than was calculated for them assuming that their constituents bave in them the same specific heat as in the free state. They think that for solid as well as for liquid and gaseous compounds the law govern- ing the specific heat is still unknown. A subsequent memoir by these physicists** treated of the specific heat of carbon in its various conditions. 10. In 1840fl H. Schrijder made an investigation as to what volumes are to be assigned to the constituents of solid and liquid compounds when contained in those compounds.In his memoirs on the subject he expressed the view that the specific heat of compounds depends on the specific heats of the constituents in * Ibid. p. 132. t Regnaul t has made known the results of these experiments in 1853 by a pre-liminary account in the Comptes Rendus vol. xxxvi p. 676 and more completely in 1862 in his u Relation dee experiences pour determiner lea loie et lee donnees physiques n6cessaires au calcul des machines feu,” vol. ii p. 3. Relation &c. POI.ii p. 289. 5 Ann. Cb. Phys. [3] i 205. 11 Ibid. [3] lxiii 31. 7 Ibid. [23 lxxv 113. ** Ibid. [3] ii 121. t-t Pogg. Ann. 1 553. 164 KOPP ON THE SPECIFIC HEAT that particular state of condensation in which they are contained in the compounds in question In 1841* reasoning from the results of Regnault’s experiments he endeavoured to show that the atomic heat (that is the product of the atomic weight into the specific heat) of a compound is equal to the sum of the atomic heats for the states of condensation in which the elements are contained in the compound and to ascertain what atomic heats are to be assigned to certain elements in certain compounds.On the assumption that the atomic heat of metals in compounds is as great as in the free state he endeavoured to determine the atomic heat of oxygen sulphur &c. in certain compounds of these elements with the metals; he came to the conclusion that an element (sulphur for instance) may in some compounds have an atomic heat different from that which it has in the free state; and the same element (sulphur or oxygen for instance) may have different atomic heats in different compounds; but the changes in the atomic heat of an element always ensue in simple ratios.I cannot here adduce the individual results which he obtained when he inferred the atomic heat of an element in a compound by sub-tracting from the atomic heat of the compound the atomic heat of the other elements in it which he had calculated either from direct determinations of their specific heat or from previous con- siderations. The essential part of Schroder’s conception is that in this manner the atomic heat of a body as a constituent of a compound may be indirectly determined; and the result is that the atomic heat at any rate of some elements in compounds is different from what it is in the free state and may be different in different compounds and that the changes are in simple ratios.Sc hro de r considered also that there was probably a connesion between these changes and those of the volumes of the elements without however stating how the one change might be deduced from the other. 11. L. Gmelin (in 1843)t considered it as inadmissible fi.om the chemical point of view to assigu throughout such atomic weights to the elements as to make them agree with Dulong and Pet it’s law. Certain exceptions must be admitted. Comparing the specific heats of oxygen hydrogen and nitrogen for the gaseous state with the specific heats of other elements in the solid @ Pogg.Ann. Xi 269. t L. Cfmelin’s Handbuch der Chemie 4th ed. vol. i p. 217. (English edition i 243.) OF 80LID BODIEg. state he came to the conclusion that if the numbers given in 9 2 as the equivalents ordinarily assumed be taken as atomic weights the atomic heat of hydrogen of nitrogen and by far the greater number of the elements is equal to about 3.2; several of them twice as great ;that of oxygen one-half; that of carbon (as diamond) one-fourth as great. With reference to the dependence of the atomic heats of the compounds on those of the elements Gmelin expressed the opinion* that in general the elements on entering into compounds retain the atomic heats they have in the free state ; but for individual elements especially for oxygen and carbon it must be assumed that their atomic heat changes in simple ratios with the compounds into which they enter.12. Waestyn was also of opinion? that the specific heats of the elements remain unchanged when they enter into chemical com- pounds. In 1848 he stated as a general proposition “The quan- tity of heat necessary to raise the temperature of the atomic weight of a body through 1’ is equal to the sum of the quantities of heat necessary to raise the temperature of the atoms and fractions of atoms through lo.” If A is the atomic weight and C the specific heat of a compound a, a2 a3 . . . the atomic weightst and c, c2 c3 . . . . the specific heats of the ele- ments contained in it and n, n2 n3 .. . . the numbers which express how many atoms of each element are contained in an atom of the compound then AC = n,a,cl +-n,a2c2 + n3a,c,...... As a proof of this law he compared the calculated values of PC of several compounds (metallic iodides and sulphides) and alloys with the observed values taking Regnault’s determinations of the specific heats of the elements and of the compounds. It follows further from that proposition that if the formula and the values for several compounds are compared with each other there must be the same differences of the values AC for the same dif- ferences of formulae. Waestyn showed by a number of examples that this is so approximately. By means of this law the product of the specific heat and the atomic weightfor one constituent of a compound may be found if this is known for the compound and the other constitneuts.Woestyn deduced in this way the product * Ibid. p. 222 :compare an earlier remark of G me1 i n which applies to this subject (1840) in the new edition of Gehler’s Physikalisches Worterbuch vol. ir p. 1941; + Ann. Ch. Phys. [3] xxiii 295. $ Wceatyn based his consideratione on Regnault’s thermal atomic weight& KOPP ON THE 6PECIFIC HEAT for oxygen (by subtracting from the product for different metallic oxides that found for the metals and from chlorate of potassium that for cliloride of potassium) to be 2.4 to 2.1 (0.=8),and for chlorine 3.0to 3.5 (Cl. =17.75). Was ty n finally expressed a doubt whether Neumann’s law is universally applicable.He laid stress on the circumstance that when two elements gave dif- ferent products the difference is also met with in the products for their analogous compounds ;and for instance the greater products which mercury and bismuth have in comparison with other elements are also met with in the compouuds of these metals. 13. Garnier (in 1852) developed the view” that not only in the case of elements are the atomic weights At inversely pro- portional to the specific heats C but that the same is the case with water and solid compounds in whose atom n elementary atoms are contained if the so-called mean atomic weight 4 be n compared with the specific heat C ;for elements A x C=3 and for compound bodies x C=3 (if 0=8).He endeavoured to n prove this from Regnaul t’s determinations of specific heats. From the latter equation he calculated the specific heat for several com- pounds. In the case of the basic oxides sulphides chlorides bromides and iodides his calculated reaults agree tolerably with the observed ones; this is less the case with metallic acids and oxygen-salts for which calculation mostly gives results far too large. Garniert drew further from the above proposition the conclusion that the atomic weight of hydrogen chlorine &c. must in fact be taken only half as great as the respective equiva- lent weights; for only by assuming this smaller atomic weight is the mean atomic weight such that its product with the specific heat is near 3. In 1852 BancalariG repeated that the specific heat of an atom of a compound body (that is its atomic heat) is equal to the sum of the specific heats of the individual constituent simple atoms and showed from a series of examples (oxides chlorides sulphates and nitrates) that according to that proposition the * Compt.Rend. xxxv 278. + Tf Regnault’e thermal atomic weights are taken. $ Compt. Rend. xxxvii 130. 5 An abstract from Memorie della Accademis delle Scienze di Torino [2] vol. xiit p. 287 in the Archives des Sciences Physiques et Naturelles vol. uii,p. 81. know the contents of this memoir only from thia ab-t OF SOLID BODIES. atomic heats of many compounds may be calculated in tolerable approximation with those derived from R egn aul t ’s experimentd investigations if for the elements which he investigated the atomic heats derived from his determinations be taken as a basis that is for oxygen (0~8)the atomic heat 1-89;for chlorine (C1= 1773) 3-21; for nitrogen (N= 7) 3.11.Caunizaro (in 1858 *) has used the proposition that in AC the sense above taken universally -ia constant for the pur- n pose of ascertaining the value of n for the atomic weight of different compounds and therewith ascertaining the atomic weight of elements which are contained in these compounds. 14. Besides those of Regnault but few experimental deter- minations of the specific heats of solid bodies have been published. Bedet and Bystrom 1 have published investigations on the specific heat of several metals at different temperatures $ both sets of experiments were made by the method of mixtures.From the year 1835 Per son 11 in his investigations on the specific heat of ice then on the latent heats of fusion and their relations to the specific heats in the solid nud liquid state has determined the specific heat for several solid substances especially also for some hydrated salts. He worked more especially by the method of mixture. He observed 7,in the case of these salts that their epecific heats may be calculated in close approximation with those found experimentally on the assumption that the coustituents anhydrous salt and water considered as ice have the same specific * 11 Wuovo Cimento 001. vii p. 321. Piazza also gives a statement of this speculation in his pamphlet “ Formole atomistiche e typi chimici,” 1863.I know this only from a notice in the Bulletin de la Soci6tB Chimique dc Paris 1863. I. An abstract from the Bulletin de YAcad5mie des Sciences de Belgique vol. xxii p. 4’73 and the MBmoires Couronne‘s par I’dcademie de Eelgique vol. xxvii ap- peared in the Bericht iiber die Fortschritte der Physik im Jahre 1855 dargestellt von der physicalischen Qesellschaft zu Berlin p. 379. $ Abstract from the Oversigt of Stockholm Vetenskaps-AkademieG FGrhandlingar 1860 in the same Jahresbericht 1800 p. 369. b To the experiments of Dulong and Petit on this subject mentioned in 9 3 Poui llet’s determinations of the specific heat of platinum at different temperatures must be added (Compt.Rend. ii ’782). 11 Compt. Rend. xx 1457 ;xxiii 162 and 366. Ann. Ch. Phys. [3] xxi 295 ;xxiv 129 ; xxvii 250 ;xxx 78. B Person expressed this in 1845 (Compt. Rend. xx l45’7) with regard to his determinations of the Ypecific heat of cryatallised borax and of ordinary phosphate of soda. He haa subsequently published the results of his experiments for the latter salt (Ann.Ch. Phys. [31 xxvii 253) but I cannot find the number which he found for crystallised borax. 168 KOPP ON THE SPECIFIC HEAT heats in them as in the free state. By the same method Alluard * (in 2859) determined the specific heat of napthalene. Schafarikt lastly has executed by the method of mixtures a series of experiments on the determination of the specific heats of vanadic molybdic and arsenious acids.Quite recently (1863) P a p e 1has published investigations on the specific heat of anhydrous arid hydrated sulphates. He worked by the method of mixture which he modified in the case of salts rich in water by placing them in turpentine and observ- ing the increase of temperature produced in the salt and in the liquid by immersing heated copper. As a more general result Pape finds that for hydrated sulphates of analogous formulae the products of the specific heats and the equivalents are approxi- mately equal ; and further that with sulphates containing different quantities of water the product of the specific heat and the equivalent increases with the quantity of water in such a manner that to an increase of each one equivalent there is a corresponding increase in the product.15. In the preceding paragraphs I have collated as far as 1 know them the investigations on the specific heat of solid bodies on the relations of this property to the atomic weight and on the connexion with the chemical composition of a substance. The views which have been expressed relative to the validity of the law of Dulong and Petit 8 and that of Xeumann and also as to the question whether the elements enter into chemical compounds with the same specific heats which they have in the free state or with modified ones are various and often discordant. In this respect it may be dificult to express an opinion which has not been already either stated or hinted at or which at any rate can- not be naturally deduced from a view previously expressed.The results to which my investigations on the specific heats of solid bodies have led me are the following :-Each solid substance * Ann Ch. Phye. [3] lvii 438. + Berichte der Wiener Akademie der Wiseenschaften xlvii 248. Pogg. Ann. cxx 337 and 579. tj The universal validity of this law was also defended by Bredow On the rela- tion of the Specific Heat to the Chemical Combining Weight.” Berlin 1838. I know this paper only from the mention of it in the new edition of Oehler’e “Physicalisches Worterbuch,” ~01,.x p. 818. It is also admitted by Mann in his attempt to deduce this law from the undulatory theoryof heat. (1857 Schlomilch and W iltzschel’s “Zeitschrift fur Mathematik und Physik,” 11.Jahrgang p. 280); and by Stefan in his investigation on the bearing of this law on the mechanicd theory of heat (1859 Berichte der Wiener Akademie vol. xxxvi p. 85). OF SOLID BODIES. at a sufficient distance from its melting-point has a specific heat which may vary somewhat with physical conditions (temperature greater or less density amorphous or crystalline conditions &c.) ; yet the variations are never so great as must be the case if a variation in the specific heat of a body is to be held as a reasoa for explaining why the determinations of the specific heats of solid elements do not even approximately obey Dulong and Petit’s law nor those of solid compounds of analogous chemical constitution Neumann’s law.Neither law is universally valid although I have found that Neurnann’s law applies in the case of many compounds of analogous atomic composition to which on account of their totally different chemical deportment different formulas are assigned ; and even in cases in which these laws have hitherto been considered as essentially true the divergences from them are material. Each element has the same specific heat in its solid free state and in its solid compounds. From the specific heats to be assigned to the elements either directly from experi- mental determination or indirectly by calculation on the basis of the law just stated the specific heats of their compounds may be calculated. I show the applicability of this by a great number of ex amp1 es .In reference to this calculation of the specific heats of solid bodies I may here make a remark. The agreement between the 9esults of calculation and experiment is often only approximate ; and it is important to bring the approximation closer. On the other hand we may be allowed to ask What means are there of even approximately predicting and calculating before-hand the specific heat of any inorganic or organic solid compound when nothing but its empirical formula is given? to which among the numbers 0.1 0.2 0.3 . . .. . . may it come nearest? Against this uncertainty may be set the differences between calculation and observation exhibited by the numbers in 0 103 to 110. My proof of the propositions given above is based on deter-minations made by earlier inqiiirers and on a not inconsiderable number of my own.I first describe the method by which I worked and then give the results which I have obtained by its means. PART11.-Description of a method of determining the Specific Heat of Solid Bodies. 16. I have worked by the method of mixture. It is not neces- 170 KOPP ON THE SPECIFIC HEAT sary to discuss the advantages which this method has over that of the ice-calorimeter at any rate in requiring smaller quantities; nor as compared with the method of cooling need I discuss the uncertainties and differences in the results for the same substance which are incidental to the use of this method and which Regnault has detailed.* The method of mixtures has been raised by Neumann and by Regnault to a high degree of perfection.Although by Neum ann’s method it is possible to determine more accurately the temperature to which the body investigated is heated Regnault’s method allows larger quantities to be used and gives the specific heats of such substances as can be inves-tigated by it as accurately as can at all be expected in the determination of this property. In the case of copper and steel it is not merely possihle to determine their specific heats by its means but also to say whether and how far there is a difference in the first metal according as it has been heated or hammered and in the second according as it is soft or. hard. It may be compared with a goniometer which not only measures the angles of a crystal but also the differences in the angle produced by heat; or it may be compared to a method for determining the specific gravity of a body by which not only this property but also its changes with the temperature may be determined.But along with such methods simpler ones though perhaps less accurate have also their value. Which method is the most con- venient or which ought to be used in a given case depends on the question to be decided by the experiment or on the extent to which the property in question is constant in the siibstance examined. With regard to the relations of the specific heat of solid bodies to their atomic weight and to their composition Regn ault’s deter- minations have shown that both Dulong and Petit’s and Neumann’s laws are only approximate and that even the accuracy in determining the specific heat which Re gnaiilt attempted and obtained could not show that these laws were quite accurate.Although the description of Regnault’s- mode of experiment-ing is so widely known yet it caiinot be said to have become the common property of physicists or to have found an entrance into the laboratories of chemists to whom the determination of the specific heat is interesting from its relation to the atomic weight. Ann. Ch.Phys. [2] lxxiii 14;[a] ix 327. OF SOLID BODIES. Very few experiments have been made by this method other than the determinations of Regnault. The method depends on the use of an apparatus which is tolerably complicated and takes up much room.Each experiment requires a long time and for its performance several persons are required. Regnault has usually worked with very considerable quantities of the solid substance and in by far the majority of cases at temperatures (usually up to 100') which many chemical preparations whose specific heats it is important to know do not bear. In the sequel I will describe a process for the performance of which the apparatus can be readily constructed and for which one operator is sufficient; by which moreover the determination of specific heat can be made with small quantities of the solid substance and at a moderate temperature. The method as I have used it has by no means the accuracy of that of Regnault; but the results obtained by it are capable of increased accuracy provided the experiments are exe- cuted on a larger scale and within greater ranges of temperature.17. The principle which forms the basis of my method is as follows :-To determine the total increase of temperature produced when a glass containing the substance to be investigated covered by a liquid which does not dissolve it the whole previously warmed is immersed in cold water; to subtract from the total increase of temperature that due to the glass and the liquid in it and to deduce from the difference which is due to the solid sub-stance its specific heat. If with regard to gain or loss of heat the glass in so far as it comes in contact with water is equivalent to x parts of water and iff is the weight of the liquid in it y the specific heat of that liquid m the weight of the solid substance M the weight of the water in a calorimeter including the value in water of the im- mersed part of a thermometer and of the calorimeter T the tem- perature to which the glass and its contents have been heated before immersion in water and T' the temperature to which the glass sinks when immersed in the water while the temperature of the latter rises from t to t' then the specific heat (sp.H.) of the solid substance is M(t' -t) -(X + ft~) . (T-'I"). sp. H = m(T -T') The glass vessel in which the substance is confined (a in fig. 1) is a tube of glass the bottom of an ordinary test-tube. In it fits 172 KOPP ON THE SPECIFIC HEAT but not air-tight a cork c which is pressed between two small brass plates screwed to a wire b.The solid substance to be investigated in the form of thin cylinders or in small pieces the size of a pea along with a liquid- of known specific heat which does not dissolve it are placed in the tube in such a manner that the liquid covers the solid substance and that there is a space between the liquid and the cork when it is inserted. The glass when the cork is fitted may be suspended to the balance by the wire 6. Three weighings (1) of the empty glass (2) after intro- ducing the solid substance and (3)after introducing the liquid give the weight of the solid substance (m)and of the liquid df). FIG. 2 Q The heating apparatus (fig. 1)serves to raise the temperature of the glass with its contents.The glass is dipped in a mercury- bath A near its upper edge and retained by a holder E. The mercury-bath which consists of a cylindrical glass vessel is sus-pended by means of a triangle round the neck of the vessel in an oil-bath B which stands on a tripod C and can be heated by a spirit-lamp D. A thermometer d,# fixed to the holder F is also immersed in the mercury-bath. The flame of the spirit-lamp may be regulated so that the * The figures are oneeixth of the natural size. OF SOLID BODIES. thermometer d indicates the same temperature for a long time." As soon as it may be assumed that the contents of the glass a have also risen to this temperatiire then the wire b being firmly held in the right-hand by its hook and the clamp of the holder E in the left the glass a is to be rapidly removed from the heating vessel to the calorimeter H (fig.2). This is almost the only part of the experiment requiring much practice ; the transference of the glass a from the one vessel to the other must be effected in an instant and none of the liquid in the glass must touch the cork. The calorimeter H stands upon a support G (fig. 2)7 on which there is an oval metal plate 0. In this there are three depressions in which fit the three feet of' the calorimeter (they are made of very thin hard brass wire). The calorimeter is oval-shaped and is made of the very thinnest brass plate. In it 5ts a brass stirrer made of two parallel plates of equally thin brass which are joined below by thin wires and provided with a thin wire ending in a 'little button i serving as handle.The plates of the stirrer are perforated in such a manner that the glass a and a thermometer can be passed through them. Fig. 3 shows more distinctly the construction of the stirrer also the section of the calorimeter. For the experiments the calorimeter is always filled as nearly as possible with the same quantity of water. The stirrer is immersed and a thermometer f dipping in the water gives its temperature which is kept uniform by an upward and downward uniform motion of the stirrer. When the tube a is brought into the water of the calorimeter it is fastened in the clamp of the holder K which is arranged like the forceps used for blowpipe experiments so that it stands on the bottom of the calorimeter and then the stirrer is set to work.This motion of the stirrer arid therewith of the water must be moderate atid uniform in all experiments ; this is of some importance for the uniformity and comparability of the experiments. The temperature indicated by * In order to obtain temperatures constant at about 50°,a spirit4amp with a thin wick is used and this is pressed in the sheath EO that the alcoholvapour above it burns witch a very small flame. The positiirn of the wick and the intensity of the flame may be conveniently regulated if the upper part of the wick is surrounded by a spiral of thin copper wire whose ends project froiii the sheath. t In making the experiment the actual distance between the calorimeter and the heating apparatus must be grcater than is indicated in the figure but not BO great that the glass a cannot by a rapid motion of the arm be transferred from the mercury-bath to the calorimeter.VOL. XIX. 0 KOPP ON TFIX SPEC%FTCHEAT the thermometer f rises and soon attains its maximum which continues for some time and can be observed with certaisty. With this the experiment is concluded. The tube a can br taken from the Calorimeter dried aud used for a new experi- ment. The increase of temperature produced in the calorimeter by the tube a and its contents would be incorrectly given if the warmth of the body of the operator who moves the atirrer an observes the thermometer acted on the calorimeter. This prevented by a glass screen gggg fig.2 which is fitted in tht brackets h h and above which the handle of the stirrer projects 18.This process for determining the specific heat of soli0 hodies has the following advantages over those hitherto princi- pally used :-The use of the mercury-bath makes it possible readily to -produce; and maintain for any adequate length of time any temperature desirable in such experiments. The mercury- bath* shares with the air-bath the advantage that nothing whicl. might influence the thermal effect in the calorimeter can adhere tc tbe substance heated in it (in this case the tube and contents) when it is removed. Over the air-bath it has the advantage tha any body placed in it takes the temperature of the surroundin( medium much more quickly through its entire mass.The corn munication of heat to the solid substance is materially promoted by the circulation of the liquid in the tube between its particles the time necessary for the entire contents of the glass to becomc equally heated is a very short one. Moreover this very circula- tion of the liquid between the particles of the solid ensures a quicker and more uniform transmission of the heat of the content! of the glass to the water of the calorimeter ;the maximum tem- perature of this water is soon attained although the transmission of the excess of temperature must take place through the sidw of the glass. The apparatus just described is very simple. It is readily con- structed; the chief point is to have two thermometers which have been compared with each other one of them (f) graduate6 in tenths of a degree while on the other (d)the tenth of a degree can be observed with certainty.The apparatus does not require much space; yet while the experiment is being made rapid changes in the temperature of the surrounding air must be avoided. In 1848 I already used such a one for heating liquids enclosed in glrtas tubes in determining their apecific heats (Poggendorff’s“Anmlen,’’ POI. lxxv p. 98). OF SOLID BODIES. One observer only is required. The experiments which I shall communicate prove that by means of this apparatus the specific heat of solid substances even when only small quantities are taken (in most cases I worked with ouly a few grammes) may be deter- mined with an accuracy not much less than that attained with larger quantities in more complicated processes.20. In order to appreciate the trustworthiness of the results arrived at by my mode of experiment it is important to state with what amount of accuracy the data of observation and the ancillary magnitudes were determined. For observing the temperature of the water in the calorimeter I used thermometers made by Geissler of Bonn which the kind- ness of Professor Buff Director of the Physical Cabinet in Giessen placed at my disposal. In these thermometers the tube consists of a fine glass thread drawu out at the lamp. The bulb is cylin-drical very thin in the glass and contains but little mercury. On one (a) 1"C. corresponds to a length of almost 5millims.on the scale and ou the other (r) to almost 4.5 millims. Tenths of a degree can be read off directly on the scale and it is easy to learn to estimate hundredths safely. I have repeatedly compared these two thermometers betweeu 70 and 24O with two normal thermo- meters of my own construction which agree very well with each other and on one of which a division corresponds to 0°*4878,and the other to OO.4341. The differences of the indications between the Geissle r's thermometers and these could be considered as constant with those limits; for the differences thus observed all the readings made with the Geissler's thermometers had to be corrected to make them comparable with the indications of the normal thermometer.The temperature of the mercury-bath was ascertained by means of one of these normal thermometers and the indications of this thermometer immersed in the bath (d in fig. 1.) corrected for the lower temperature of the mercury-thread out of the bath; this 1a.tter temperature was given with adequate approximation by the second thermometer e.* 21. The weight of the thin sheet-brass calorimeter together with stirrer was 11-145 grms.? Taking the specific heat of brass The paragraphs in this abstract are numbered as in the original memoir. 't At the beginning of these investigations. During their progress the calorimetet was cleaned and dried with bibulous paper a countless number of times so that itt weight diminished by about 0.04 grm. in the course of the experiments.In deter-02 KOPP ON THE SPElCIFfC HEAT according to Regnault at 009391 the calorimetric value in water of this mass of metal is 1-046 grm. Considering that the calorimeter in the experiments was not quite filled with water but about &th remained empty even after introducing the tube I put the value in water at 0.872. In determining the calorimetric water value of the immersed parts of the thermometers r and b the following experiments were made. The weight of water in the calorimeter together with tl,# reduced weight of the metal was 30.87 grms. When the ther- mometer r heated to 33O.86 was immersed the temperature rose from 10'-73 to lOo-85;the immersion of the thermometer b at a temperature of 370-53caused a rise from 10"*61to 10O.76.In both cases the temperature of the water was indicated by means of the other thermometer the reduced value of which might be neglected under these circumstances. These experiments gave 0.16 as the reduced value of the thermometer r and 0.17 as the reduced value of the thermometer b. The thermometers have very nearly the same dimensions. Hence I put the reduced value of the calorimeter (that is of the part of the metal concerned). of the stirrer and of the immersed part of the thermometer a 1-04grm. Even if this determination is a few tenths out it i scarcely appreciable as compared with the quantity of water in the calorimeter In all following experiments this was between 25.85 and 25.95 grms. All the subsequent determinations depend on fixing differences of weights and of temperatures.The accuracy of the results depends on the precision with which both kinds of magnitudes are ascertained ; and it is useless to determine the weights to rlba or nearer if the differences in temperature cannot be determined more accurately than to or -&. I have weighed to centi- grammes instead of to milligrammes by which the time necessary for the weighings is much shortened and their accuracy not materially lessened. 22. The reduced value x remained to be determined of the glasses (cylindrical tubes of thin glass see 0 17) or rather of that part which was immersed in the water of the calorimeter the quantity of which was always the same. In the following T is the temperature to which the glass in the mercury-bath was heated (compare fig.I) M the quantity of water in the calori- mining the weight of water used in each experiment the weight wbich the calori-meter actually had at the time waa taken as bssis. OF SOLID BODIES. meter + the reduced value in water of the other parts of the latter which required to be taken into account t the temperature of the water in the calorimeter when the glass was immersed (fig. 2) and r the temperature to which the water became heated and which must be considered as that to which the glass cooled.* We have then M(T -t) x= T-7 In my experiments I used three glasses which may be called 1 2 and 3. To ascertain the reduced value of glass 1 I made the following determinations :-Temperature of Air 15'-8.T. I-. t. M. 2. 0 78.54 0 17.23 0 15-72 grms.26.98 0.664 14-38 17-16 15-78 26.97 0.651 7551 17.14 15-72 26.92 0.655 76-06 17.15 15-73 26.945 0.649 77-32 17.22 15.74 26.96 0.664- Mean.. 0.657 A second series of experiments made in a similar manner to determine the reduced value for glass 1 gave the following re- 8dtS :-Temperature of the Air 19"*9-19O.8. T. T. t. M. X. grms. 0 0 0 78.50 21-32 19.93 26.99 0.656 81-86 21.47' 20.03 26-98 0.643 80.42 21.43 20.02 26.98 0.645 79-77 21.42 20.03 26.935 0.642 80.14 21-51 20.12 26.955 -0.639 Mean.. 0.645 The mean of these two means 0.657 and 0.645 gives as the reduced value in water of glass 1 0.651 grm. * If the cork which closes the glaw and by means of the wire passing through it enables it to be handled is moist incorrect and discordant values are obtained for it owing to the evaporation of water in the empty glass so long as this is in the mercury-bath,and to the condensation of aqueous vapour in the glass when it is immersed in the calorimeter.KOPP ON THE SPECIFIC REAT In like manner the reduced water-value of glass 2,was found to be 0.487 and that of glass 3 was found to be 0.453. 23. In those experiments in which a glass containing a liquid and perhaps a solid substance is immersed while warm in the water of the calorimeter it may be asked if when the water has become heated to a certain maximum temperature the contents of the glass have actually cooled to the same temperature.IN earlier experiments made by the method of mixture it was at once assumed that the temperature assumed by the water of the calorimeter after immersing the solid was actually that also to which the immersed body sank. Neumarin has taken into account that the immersed body when the water shows its maximum temperature may have a somewhat higher tempera- ture.* Avogadro has also taken this into account,t arid Regnault has also allowed for this circumstance in the case iii which the mass immersed in the water of the calorimeter is a bad conductor of heat.$ A correction for this fact is certaiiilp in-considerable and unnecessary if the immersed body conducts heat well and the range of temperature through which it cools in the liquid is great.This interval of teniperature was in my experi- ments considerably smaller than in those of Neumann and of Regnault; and as in my experiments the excess of heat of the contents of the glass bad to pass through its sides to the water of the calorimeter it might be doubted whether when the temperature of the water was at ita maximurn this temperature could be considered as that of the contents of the glass. I have endeavoured to answer these questions experimentally. A glass such as mas used for holding the solid investigated and a liquid was filled with water and a perforated cork fitted by means of which the glass could be handled. The glass filled with water was warmed and then placed in the calorimeter filled with water; a thermometer A passing through the cork showed the temperature of the water in the glass; a second €3 showed that of the calorimeter-water.If the glass filled with the warmer water is immersed in the cold water the following circumstances are observed.0 A sinks very rapidly while B rises more slowly ; * In the memoira mentioned in tj 4 Pape has also discussed and applied the correction to be made for the above circumstance (Pogg.Ann. cxx 341). .t. Ann. Ch. Phys. [2] Iv 90. $ Ibid [2] lxxiii 26. 0 In theee experimenta in order to insure uniformity in the temperature of the water the stirrel was kept ig continual motion wd the same proem followed as in ascertaining the specific heat. OF SOLID BODIES. if B shows the maximum temperature for the water of the calori- meter (this temperature being called t’) A gives a higher tempe- rature (T) for the contents of the glass.B then slowly sinks and A follows it while the difference between t‘ and T always becomes smaller. In the two following series of experiments I have endeavoured to determine hy how much under certain con- ditions the temperature T’ of the water in the glass exceeds the maximum temperature t’ of the water in the calorimeter when this maximum temperature as such is observed. I obtained the following results the temperature of the air in the experiments was 13°2-130.5. Experiments with Glass 1. Experiments with Glass 2. T’* t’. Difference. T’. t.’ Difference. 0 0 0 0 0 0 15.51 15.13 0.38 15.71 15.50 0.21 14-96 14.72 024 15-96 15.65 0.31 16-11 15.94 0.17 15.16 1491 0.25 15.56 35-36 0.20 14.76 14.47 0.29 14-24 1405 0.19 14-66 14.33 0.33 15-96 15.64 0.32 15-56 15.24 0.32 A closer agreement in the numbers expressing the difference between T’ and t’ is difficult to attain since a certain time is necessary to observe the occurrence of the maximum temperature and during the time in which the thermometer B remains con- stant the thermometer A still sinks ; according to the moment at which the maximum temperature is considered to be established this difference may be obtained different and the smaller the later the observation ia made.Moreover the magnitude of this difference between T’ and t’ depends on the difference between t’ and the temperature of the air.I have always endeavoured to work under the same circumstances and especially to arrange the experiments so that the maximum temperature of the water in the calorimeter did not exceed by more than 2’ the temperature of the air*. For these experiments and the apparatus which I # A preliminary experiment &om how cool the water in the calorimeter ought to be. Water which is somewhat cooler than the surrounding air may be kept in stock for such experiments by placing it in a cylindrical flask covered externally with filtering paper and standing in a dish of water 80 that the paper is always moist. To warm the water in the calorimeter it was merely necessary with apparatus of the the dimensions I used to lay the hand on it for a ahort time.HOPP ON THE SPECIFlC HEAT used I assumed on the basis of the preceding experiments that if tlie water of the calorimeter had assumed its maximum tempe- rature t’ the contents of the glass were 0’93 higher; that is I pat throughout T’ the temperature to which the contents of the glass immersed in the calorimeter had fallen =t’ i-OO.3. 24. It is a matter of course that in introducing this correction for obtaining the temperature of the contents of the glass at the time the maximum temperature has been attained in the calori-meter it is unnecessary to give the indications of T’ in hundredths of a degree; and since the temperature T to which the glass with its contents was heated in the mercury-bath only serves to deduce the difference T-T’ it is unimportant in giviiig this temperature to do so in hundredths of a degree.The accuracy of the determixiations of specific heat in so far as it depends on determinations of temperature is limited by the accuracy with which the difference T-T’ and t’ -t are determined (where t is the original temperature of the water in the calorimeter and the other letters have the meanings previously assigned to them). To have one of these differences very accurately while the other is much less accurately determined avails nothing for the accuracy of the final results. It is at once seen that in my experiments and especially in those of Neumann and Regnault the hundredths of a degree have a greater significance for the small difference t‘ -t than the tenths of a degree for the great difference T -T‘.The correction for educing the value of T’ which I have just discussed is of course more important the smaller the difference T -T’; for most of my experiments in which this difference is about 30° the significance of this correction is inconsiderable if the contents of the glass be a good conductor. I give a few numbers. The experiments giveii in 0 25 on the specific heat of mercury which by using this correction give it at 0.0335 in the mean give it =0.0331 if this correction is neglected that is T’ made = t’. The fourth eeries of experiments given in 5 27 for determining the specific heat of coalrtar naphtha A give it at 0.425 when this correction is made and at 0.420 when it is omitted.The first series of experiments in 0 33 for determiriing the specific heat of sulphur give it at 0.159 when this correction is used and at 0.152 when it is neglected. Whether in all such cases T‘ is put =t’ or =t‘O+0°*3 is of considerable importance. The correction in question is inadequate if the substance in the OF SOLID BODIES. glass is a bad conductor ; for example when the solid in the glass is a pnlverulent or porous mass in which the moistening liquid stagnates (compare 8 18). That under such circumstances the numbers obtained for the specific heat are found somewhat too small must be remembered in the case of chromium and in that of chloride of chromium. Too small numhers are also obtained if in the experiments the maximum temperature of the cooling water exceeds that of the air by much more than 2’.Such experiments are not comparable with the others for example with those made for the purpose of ascertaining the ancillary magnitudes occurring in the calculation of the results ; for them this correction is inadequate and the loss of heat which the con- tents of the calorimeter experiences between the time which elapsed between immersing the glass and the establishment of the maximum temperature is too great. 25. I first attempted to test my method by some experiments in which water or mercury was placed in the calorimeter. For the specific heats of these liquids the following numbers were ob- tained calculated by the formula :-M(t’ -t) -x(T -T‘) , sp. €3 = f (T -T’) in which the signification off is manifest from what follows that of the other letters from what has been given before.In the experiments in which a readily vaporizable liquid was contained ih the glass such as water or coal-tar naphtha a sen- sible formation of vapour took place although the tern perature did not exceed 50’. If the glass contaiuing the liquid was heated in the mercury-bath vapour was formed in the empty space below the cork which served as stopper ; if the glass was then brought into the water of the calorimeter this vapour condensed and settled partially on the stopper. The stopper did not act mate- rially on the water of the calorimeter. The quantity of liquid in the glass which acted directly on the water of the calorimeter decreased somewhat in each experiment ; but this decrease is very inconsiderable.In the following experiments f denotes first the weight of the liquid in the glass at the commencement of the ex- periment and at last its weight at the end of the experiments that is after subtracting the liquid which had vaporized and con-densed on the stopper. After the end of the experiment the stopper was dried to Temove the liquid and by another weighing KOPP ON THE SPECIFIC HEAT Of the glass together with its contents and stopper the weight of the liquid still contained in the glass was obtained. The decrease of weight of the liquid in theglass was always found to be incon- siderable and might without any harm have been neglected ; for the last experiment of a series I have always taken the diminished weight of the liquid into account hut for those between the first and the last I have neglected the diminution oE the weight of the liquid in the glass.In the following tables the values off marked with an asterisk are those which were formed after drying the stopper. Two series of experiments in which water was contained in the glass gave the following results for the specific heat of this liquid :-Experiments with Glass 1. Temperature of the Air 19'*0. T. T'. t'. t. M. f. x. ap. H. 0 0 0 0 grms. grms. grm. 45-2 209 20.62 16.83 26.945 3.43 om1 1.036 46.6 21.2 20.92 1'7.03 26.936 , 1,013 47.4 21-3 20.96 17'03 26.966 3*42* , 0.917 98 Experiments with Glass 3.Temperature of the Air 19O.O. T. T'. i?. t. M. f. x. ap. H. 0 0 0 0 grms. grma grm. 46.8 21.1 20.76 17.03 26-96 3.445 0.453 1.004 46.8 ai-1 20.83 17.12 26.986 , , 0.999 47-0 21.2 20.93 17.22 26,936 3.435* , 0.996 The value found for the specific heat of the contents of the glass comes very near the Dumber 1 assumed for the specific heat of water. Determinations in which mercury was contained in the glass gave the following results for the specific heat of the contents of the glass. Experiments with Glass 1. Temperature of the Air 13°*8-140.4. T. T'. e. t. M. f. x. sp. H. 0 0 0 0 grms. grms. grm. 61.1 16.8 16'50 13-41 26.946 53.016 0.661 0.0235 48-5 16.8 16.48 13.64 26.96 2) , 0.0333 45-2 16.6 16-20 13-63 26.966 9 ,j 0.0333 Experiments with Glass 2.Temperature of the Air 13°*8-140 4. T. T'. t'. t. M. f. x. ap. R. 0 grms. grm. grm. 0 0 0 50.0 17.1 16-79 13'74 26,935 60.015 0.487 0.0335 45.6 16-7 16-41 13'12 26'936 9 , W0337 OF SOLID BODIES. The mean of these five determinations gives 0.0335 for the specific heat of mercury in accordance with the results found by other observers for this 0' between(0,0330metal and loo" Dulong and Petit; 0.0333,Regnault). 26. For the liquid which is to be placed in the glass along with the substance whose specific heat is to be investigated I could in many cases use water ; but many substances the determination of which is important dissolve in water and hence I had to use a different liquid. Coal-tar naphtha has the advantage that it is a mobile liquid does not dissolve most salts and does not resinify in contact with the air ; but its odour is very disagreeable especially on continuous working respiring air charged with its vapour appears to act injuriously on the organs of the voice.As compared with water coal-tar naphtha has the disadvantage that its specific heat must be specially determined and any possible uncertainty in this is transferred to the determination of the specific heat of the solid substance ;but the thermal action of a given volume of naphtha is only about 3 that of the same volume of water ; and in experi- ments in which the thermal actioii of a solid substance is deter-mined along with that of the necessary quantity of liquid which is contained with that substance in a glass the thermal action due to the solid is a larger fraction of the total if coal-tar naphtha is used than if water is the liquid which is a favourable circumstance in the accurate determination of specific heat.As it was more especially important to obtain comparability in the results for specific heat I have for a great many substances which are in- soluble in water and for whose investigation water might have been used also employed coal-tar naphtha. Water was used for a few substances which are soluble in coal-tar naphtha (sulphur phosphorus sesquichloride of carbon for instance). Several sub- stances I determined both with water and with naphtha; the results thus obtained agree satisfactorily. To the question as to whether any possible change in the specific heat of naphtha with the temperature can be urged against the use of this liquid I shall return in a future paragraph.27. The coar-tar naphtha A which I principally used in the subsequent experiments was prepared from the commercial mix- ture of hydrocarbons C,H, -6 'by purifying it with sulphuric acid treating the portion which distilled between 105" and 12O0 with chloride of calcium for six days then again rectifying it and collecting separately that which passed between 105O and 120". 184 KOPP ON THE SPECIFIC HEAT This liquid had the specific gravity 0.869 at 15'. Four series of experiments made to determine its specific heat gives as a mean result the number 0.431 between 14"and 52O.Another sample of coal-tar naphtha B used in some of the ex- periments was found to have a specific heat = 0.419 between 20" and 50". 29. My experiments were made at very different tempera-tnres. The temperature of the air was often something under lo" sometimes above 20'. These numbers represent the limits to which the liquid in the glass together with the solid substance cooled in the calorimeter. In most experiments I heated the glass with its contents to about 50° in some cases not so high. Now for the various intervals of temperature within which the liquid in the glass cooled can its specific heat he assumed to be always the same? For water this may be done and for coal-tar naphtha I did not doubt it while engaged in my experiments.I first when they were finished became acquainted with Reg-nault's * investigations on the specific heat of liquids at various temperatures ; according to these experiments the specific heat of some liquids considerably increases with the temperature. I have not directly investigated coal-tar naphtha in this respect but it is probable that the specific heat of this mixture of hydrocarbons C H, 6 alters but little with the temperature and it is certain that this change is without influence on the accuracy of my deter-minations of the specific heats of solid substances. Regnanl t's experimentsf made by the method of cooling show no change for benzole C&, between 20' and 5" while there is a distinct change in the case of alcohol. For pure benzolet I found the specific heat by the method of mixture to be 0.450between 46' and 19"; Eegnaults found it between 71" and 21" to be 0.436.These numbers obtained with different preparations are not indeed comparable for a decision of the question just discussed but they render improbable a considerable increase in the specific heat of benzole with the temperature. What 1more especially lay weight upon is this the specific heats of solids which I have determined at various temperatures by their agreement with the Relation des expkriences ..,.pour de'terminer les lois et le8 domi58 physiques nkcessaires au calcul des machines B feu vol. ii p. 262 (1862). t. Ann. Ch. Phye. [3] ix 336 and 349. $ Pogg. Ann. lxxv 107. 5 Relation &c. . ii 288.OF SOLID BODIEB. numbers previously found by others do not indicate any influence of a change of specific heat of naphtha with the temperature. In the preceding method of experiment whether water or naphtha of the kind described is contained in the vessel a tempe- rature much higher than 50’ cannot be employed; for otherwise the quantity of liquid evaporating and condensing on the stopper becomes far too considerable. Perhaps with hydrocarbons of higher boiling-points higher temperatures might be ventured upon. PART111.-Determination of the Specific Heat of Individual Solid Substances. 31. By the method whose principle and mde of execution have been discussed in the preceding paragraphs I have determined the specific heat of a large number of solid substances.* I should have liked to include a still larger number of bodies in my inves-tigations ; but a limit was put by the straining of the eyes from constant reading of finely divided scales and by the injurious action which the long-continued wcjrking with coal-tar naphtha produces.32. The signification of the letters in the statement of the fol-lowing experiments and their calculation is clear from 5 17; in reference to the value of the numbers for M compare 5 21 for x 5 22 for l” 5 23; y denotes the specific heat of the water or naphtha used in the experiments. 33. SuZphur pieces of transparent (rhombic) crystals from Girgenti. I made three series of experiments with this sub-stance. 1.-Experiments with Water.Glasa 1. Temperature of the Air 13O.2. T. T’. t? t. M. m. j. y. x. sp. H. 0 45 8 0 15-5 0 15.24 11.74 grms.26’95 grms.4.16 grm.1.765 1.000 w. 0.651 0.168 46.0 45 2 45.8 16.2 16.0 16.4 15-93 15-73 16-05 12.52 12-42 12-74 26.935 26-945 26.96 , , , $9 Y? 1.75 99 1j , , , , 0.160 0.153 0-153- Mean .. 0.159 * We give in this abstract only a few of Professor Kopp’s determinations in de. tall referring for the rest to the original paper.-ED. 186 HOPP ON THE SPECIFIC HEAT 11.-Experiments with Water. Glass 2. Temperature of the Air 13O.2. T. T'. C. 1. M. m. 3 y. 5. sp. H. 0 0 0 grma grms. grme. gm* 45-8 16.4 16.07 12.36 26.96 4-815 2.09 1.000 0.487 0.171 47.3 16.6 16-33 12.46 26.95 ,) 0.170 0156 1) YY ,¶ ,¶ 441 16.5 16-15 12-74 26.925 ) Yt n 45-1 16.6 16-28 12.77 26.96 ,¶ 2.w , 0.159 -,¶ Mean ..0'164 111.-Experiments with Water. Glass 3. Temperature of the Air 17O.2. T. T'. t'. t. M. n. f. y. x. sp. H. grms. grms. grms. gm* 26.99 4'92 2.065 0.453 0.166 W 0 0 43.7 19.1 18-83 , 15.79 1.000 43 6 19.1 18.84 15.84 26-97 ) ,) 0.162 99 3 43.3 19.2 18-92 15.92 26-94 ) Y9 9s ,) 0.170 43.1 19.2 18.87 16.93 27-98 , 2.05' ) , 0.166 -Mean .. 0.166 Taking the mean of the means obtained in the three series of experiments 0.159 0.164 0.166 we obtain 0.163 as the specific heat of rhombic sulphur between li0and 45O. By the method of cooling D u 1o n g and Pet it found the specific heat of sulphur at the mean temperature to be 0.188; Neumaiin found 0.209by the method of mixture; for sulphur which had been purified by distillation fused and cast in rolls Regnault foundt the specific heat between 14' and 98O to be 02026.In these experiments a dxelopment of heat depending on a change from amorphous sulphur iuto rliombic-crystallised appears to have co-operated and to have caused the circumstance observed by Regnault that after immersing the heated sulphur in the water of the calorimeter the maximum tcniperatiire was set up only after an unusually long time. Sulphur which has solidified after being melted usually contains an admixture of amorphous sulpliur-the greater the more the melting point has been exceeded-which at the ordinary tern- perature passes slowly at 100" more rapidly into crystallised accompanied by disengagement of heat.The transformation of the sulphur set up by the heating and continued in the water of the calorimeter brought about this slow appearance of the maxi-mum temperature and made the specific heat appear too great; * After drying the stopper. 'b Ann. Ch. Phys. [2]lxxiii 50. OF SOLID BODIES. 187 for Regnault's subsequent determinations,* also made between 97" and 99O and the mean temperature gave it considerably less; 0.1844 for freshly melted sulphur (in which superfusion had been avoided?); 0.1803 for sulphur which had been melted two months; 0.1764 for what had been melted two years (and which had then given 0.2026); 0.1796 for sulphur of natural occurrence. The difference between the latter result and my own doubtless depends partially at least on the fact that Regnault's determination was made between 14' and 99" (the latter of which temperatures is very near the melting point of rhombic sulphur) ; mine was made between 17"and 45O.t 34.Boron.-I have made some experiments with 'this substance which have some interest for the question whether this body has essentially different specific heats in its different modifications ; but the results are not very trustworthy owing to the spongy nature of the amorphous boron and the doubtful purity of the cry st allised variety. The amorphous Boron$ which I investigated was pressed in small bars and had stood several days in vacuo over sulphuric acid. Experiments with Naphtha A.Glass 1.$ Temperature of the Air 17°*0-170.2. T. TI. t'. t. M. m. f. g. 2. sp. H. 4i.O 1i.7 108.73 l"s.36 26.955grms. 1-52grm. 2.515grms. 0.431 0.651grm. 0.246 48.1 18.6 18-65 16.23 26.965 , 99 9 , 0254 48.0 47-9 18.6 18.7 18-64 18.72 16.33 16.42 26.95 26% , , 9 2*491! 9 , , , 0.252 0.262 - Mean .. 0.254 Even if the results of the individual experiments agree tolerably with each other they are not very trustworthy ; for the quantity of boron (only 1&grm.) is very small and the amount of heat due to the boron is a very small part of the total (comp. 4 19). Yet I do not consider the result of the above series of experiments (that Ann. Ch. Php. [3] ix 826 and 344. i. There is nothing known certainly as to whether the different modifications of sulphur have ementially different specific heata Marchand and Scheerer's experiments on brown and yellow sulphur made by the method of cooling compare in Journal fur Prakt.Chemie vol. xxiv p. 153. $ Prepared from boracic acid by aodium and treated with hydrochloric mid."-Wohler. 5 See page 1'77. 11 After drying the stopper. KOPP I ON THE SPECIFIC HEAT between 18' and 48' the specific heat of amorphous boron is about 0.254)as very far from the truth. There are no consider-able accidental errors of observation in these experiments to judge from their agreement with one another. Of the constants for calculating the experiments x and y must be taken into account in regard to any possible uncertainty. It has been assumed that x=0*615 and y=0.431; if we took x=0*63 and y=0*41,the specific heat as the mean of four experiments would be =0*30; if x were 0.67 aud y 0.45 the specific heat would be 0.21.But from what has been communicated in 0 22 and 0 27 in reference to the determination of x and y it cannot be assumed that any possible uncertainty in reference to these values can reach either of the above limits. It can be assumed with the greater certainty that the specific heat of amorphous boron is between 0.2 and 0.3 and nearly 025 because x and y could not simultaneously both be found too great or too small (if x had been too small y would have been too great and vice versci). Crystallised Boron*. Experiments with Naphtha A. Glass 3. Temperature of the Air 18°.9-180.7.T. T'. t'. t. M. m. f. y. x. sp. H. 0 50.9 0 20.8 0 20.52 0 18.53 grms. 26.94 grms. 2.82 grm. 1.53 0.431 grm. 0.453 0.237 51 3 20.8 20.52 18.52 26.975 , 9 99 , 0.233 51.5 51.4 20.8 20.8 20.53 20.46 18.53 18.43 26.985 26.99 , , I 1-52? n , , , 0-229 0.222 I_ Mean .. 0230 Hence the specific heat of the crystallised (adamantine) boron investigated is 0.230between 21' arid 51"; it is pretty near that found for amorphous boron 0.256. Regn aul t found $ (between 98' and 100' and the mean temperature) 0.225 for a specimen of crystallised boron prepared by Rousseau; 0.257 for one pre-pared by Debra y ; 0.262 for one obtained from Deville; and 0.235 for a specimen of graphitic boron prepared by Debray. The specific heat of amorphous boron could not be determined by * '' Made in Paris probably by Rousseau and doubtless by melting borax with aluminium.To conclude from its external appearance it probably contained Borne aluminium and carbon ; compare the analjsis in Ann. Ch. Pbarm. ci. 347. + After drying tbe stopper. $ Ann. Ch. Phys. [3] lxiii 31. OF SOLID BODIES. 189 Regnault’s method because when heated to looo in air it partially oxidizes into boracic acid with disengagement of heat (three experiments in which the quantity of boracic acid formed was tletermiued and its specific heat but not the thermal action due to the formation of hydrated boracic acid in immersion in water allowed for gave respectively 0.405 0.348 and 0.360 which numbers Regriault does not consider as even approxi- mately representing the specific heat of amorphous boron) and when greatly cooled disengages a quantity of air when im-mersed in warmer water which renders the results uncertain.36. Carbon.-It is known how different are the numbers obtained for the specific heat of carbon in its different forms I have determined the specific heat for comparatively only a few of the modificztions of carbon-for gas-carbon for natural and arti- ficial graphite Before the experiment each of these substances was strongly heated for some time in a covered porcelain crucible and then allowed to cool and immediately transferred to the glass for its reception and after weighing naphtha was poured over it. Gas-carbon from a Paris gas-works; very dense of an iron- grey colour; left very littie ash when calcined.* It was used in pieces the size of a pea and two series of experiments were made.1.-Experiments with Naphtha A. Glass 1. Temperature of the Air 18°.9-190.2. T. T’. t? t. M. 9n. f. y. 2. sp. H. 0 52.9 0 20.8 0 0 grms. 20.53 18.13 26.955 grms.3.135 grm.1.825 0.431 grm. 0.651 0.184 51.7 52.6 20.7 20.9 20.42 20.63 18 06 18.26 26.97 26-98 , , ,Y >> ,9, I , 0186 0.196 52.4 20.9 20.58 18.23 26’98 , 1*805+ , , 0.186 c_ Mean .. 0.188 * Thiscarbon as well m the above-mentioned varieties of graphite was analyzed in the Laboratory at Giessen by Jlr. H u be r. The gas-carbongave when placed in a platinum boat and burned in a stream of oxygen-I. 11. 111. IV. v. Carbon ........,.97‘19 98.25 9’1.73 98-08 98.55 Hydrogen .... . ... 0.53 0.15 0.68 9-37 1-00 Ash ............ 0‘61 0-62 0.73 0‘23 0.69 -L_-98.33 99.02 99‘14 98.68 100.24 + After drying the stopper. VOL. XlX. P KOPP ON TEIE SPECIFIC HEAT 11.-Experiments with Naphtha A. Glass 3. Temperature of the Air 2Oo*5-2O0*8. T. T’. t’. t. M. m. f. y. x. sp. H. 0 0 0 0 grms. grms. grm. grm. 52.6 22.6 22.33 20.23 26.985 3.345 1.935 0.431 0.453 0,180 52.2 22.5 22.23 20.14 26.985 ,) 9 )) 0.183 ?9 52.3 22.5 2T20 20.12 26.965 ,) ,> ,) 0.179 39 52.5 22.6 22.31 20.22 26.955 , 1*91# , , 0.182 -Mean .. 0.181 These determinations give as the average of means of both sets of experiments the number 0.185 as the specific heat of gas-carbon between 22O and 62’.Natural graphite from Ceylon. Left very small quantities of ash when calcined.? 1.-Experiments with Naphtha A. Glass 3. Temperature of the Air 18°-9-190.2. T. T’. t’. t. M. m. f. y. x. sp. H. 0 0 0 0 grms. grms. grms. grm. 51.4 20.8 20.48 18-13 26.975 4.025. 2.085 0.431 0,453 0.1’79 9, 51.4 20.8 20.51 18.13 26.99 , 9 , 0.186 51.8 20.8 20.54 18‘15 26.975 , ; >> ) 0.181 52:O 20.8 20.54 18.13 26.99 ,) 2-06” )) ,) 0,183 Mean .. 0.183 11.-Experiments with Naphtha A. Glass 1. Temperature of the Air 19°*0-180*7. T. T’. t’. t. M. m. $ y. x sp. H. 0 0 0 grms. grms. grm. grm. 53.9 21.1 20.77 18.22 26.97 3.515 1.935 0.431 0.651 0.1’74 52.2 21’0 20.73 18.31 26-96 ) ,# >, , 0.176 9 9, 52.1 21.2 20.86 18.52 26.94 , , 0.158 ?J 53.0 21-0 20.73 18.32 26-97 ,; ,I , 0.155 52.8 21.0 20.73 18.33 26.965 ) 1.91 , , 0.160 -Mean ..0-165 * After drying the stopper. t In Mr. Huber’s analyses this substance was placed in a platinum boat then burned in a porcelain tube in oxygen. 1. Ir. III. Carbon .......... 99.11 98.52 Hydrogen ........ 0 17 0.06 Ash .......... 0.26 0.27 0.61 99.55 99.09 The residual porous ash left after the combustion was tolerably white with admixed red particles. OF SOLID BODIES. 111.-Experiments with Naphtha A. Glass 3. Temperature of the Air 19"*9-20"~0. T. T'. t? 1. M. m. f. y. Z. Bp. H. 0 51.6 0 21.9 0 21.55 0 19.33 grms.26.97 grms.3'90 grms.2.05 0.431 grm.0.453 0.174 51.3 22.0 22.71 19.52 26.955 , 99 J , 0.174 51.5 22.0 21-70 19-52 26.9'7 >, , 0.168 , )* 51.5 21.9 21-63 19-42 26.96 , 2-04" , , 0.175 *-Mean ..0.173 The average of the means of these three series of determinations 0*183,0,165,and 0.173 gives 0.174 as the specific heat of Ceylon graphite between 21" and 52'. Iron graphite from Oberhammer near Sayn separated upon black ordnance iron. Thin very lustrous laminae freed from iron by treatment with aqua regia as much as possible yet not complet e1y.t I.-Experiments with Naphtha A. Glass 3. Temperature of the Air 19"*0-18°-7. . T'. t'. t. M. m. f. Y* x. ~p.H. 0 0 0 grms. grms. grms. grm. 52.5 20.8 20.53 18.21 26.955 2.51 2 445 0.431 0.453 0.186 52.9 21.1 20'84 18.64 26.98 , 2.565$ , , 0.156 61.4 20.9 20.64 18.43 26.94 , Y, ,> , 0.157 52.0 20-9 20.60 18-33 26.99 , 2.545' , , 0.168 Mean ..0.167 * After drying the stopper. .t. This iron graphite according to Mr.Huber'a analyses in which it was also burned in oxygen in a platinum boat placed in a porcelain tube gave the following results :-I. 11. IIT. Carbon .......... 97.01 96.12 96.37 Hydrogen .......... 0.12 0.18 AS^ ............ 4-88 4-87 3-99 101.89 101.11 100.54 It is probable that both in this graphite and in that of natural occurrence the hy- drogen is not essential but arises from hygroscopic moisture. The residual ash contained porous particles consisting of sesquioxide of iron and silica and also small pellets ccvered externally with a layer of magnetic oxide of iron these dissolved in hydrochloric acid at first quietly and afterwards with disengagement of hydrogen ; and in the solution small blisters of graphite could be perceived.It is owing to the oxidation of the iron that the sum of the constituente in all cases exceeds 100. $ After mme more naphtha had been added. P2 KOPP ON TEE SPECIFIC HE-4'r 11.-Experiments with Naphtha A. Glass 1. Temperature of the Air 19°~Y-2Go-0. T. T'. t'. t. M. m. f. Y. x. sp. H. 0 U 0 grms. grms. grms. grm. 52.1 21.9 21.57 19.32 26.94 2.48 2.205 0,431 0,651 0'164 51.7 22.0 21-66 19.45 26.97 , ,a , 0.163 >9 51.5 22'0 21-73 1954 26.98 , , 0-162 9 99 51.5 22.0 21.66 19.46 26.945 , 2*19* # , 0-167 -Mean ..0.164 The average of the means of both these series of experiments 0.167and 0.164,gives as the specific heat of iron graphite between 22O and 52" the number 0.166. The results previously known with reference to the specific heat of carbon differ greatly for its different conditions as also do the results obtained by different inquirers and by different methods for the same condition. But even leaving out of consideration the numbers obtained by De la Rive and Marcet by the method of cooling there are still considerable differences between Regnault's results obtained by the method of mixture arid my own. Regnault found for animal charcoal 0.261 for wood-charcoal 0.241 for gas-carbon 0.209 for natural graphite 0.202 for iron graphite 0.197 for diamond 0.1469 ; his experiments gave greater numbers for the same substance than my own.I think that exactly for a substance like carbon in its less dense modifications my method promises more accurate results than that of Regnault. Even in mine the substance after being strongly heated before the experiment might absorb gases or aqneous vapour vhich would make the specific heat too great. But in Regnault's method this source of error might also operate and more especially also the source of error due to the disengagement of heat wheu porous substances are moistened by water. These sources of error which affect the determination of the specific heat of the various modifications of carbon and make it too high have the more infltience the looser and the more porous the substance investigated.I believe that the only certain determination of the specific heat of carbon is that of diamond and all other determinations are too high owing to various cir- cumstances and in Regnault's experiments with wood and animal charcoal &c. to the heat disengaged when these substances are moistened by water. * After drying the stopper. OF SOLID BODIES. 37. Silicium. -I have invest,igated this substance in four different modifications. Amorphous Silicium*.-For the experiments picked coherent pieces were used which had stood for several days in vacuo over sulphuric acid. Experiments with Naphtha A. Glass 3. Temperature of the Air 3 9O.2. T. T'. t'. t.M. m. J y. a. sp. H. 0 51.5 0 20.7 0 20.38 18.13 grms.26.95 grm.1.095 grms.2.88 0.431 grm.0.453 0.251 5Q.5 50.0 50.4 20.9 20.8 21.0 20.59 20.54 20.66 18.52 18.46 18'55 26.935 96.975 26.98 , , , 2.i7t ,Y 1 9 , , , 0.177 0.208 0.221 Mean .. 0.214 The very discordant results of these experiments are very little trustworthy; the quantity of silicium 1 grm. was too small and its thermal action inconsiderable as compared with that of the other substances immersed with it in the water of the calorimeter. Graphitoi'dal Silicium. 5 Experiments with Naphtha A. Glass 3. Temperature of the Air I6O.7-1iO.2. T. T'. t? t. M. m. J y. x. sp. H. grms. grms. grm. grm. 0 0 0 0 51.0 18.8 18.51 16.34 26.965 3.155 1.83 0.431 0.453 0-182 52.3 19.1 18.82 16.59 26.975 ,I , 0.181 79 9 51.1 18.9 18.62 16-44 26.98 , 9 , 0.185 Yf 50.4 18.8 18.52 16.43 26.95 9 1-U-l 9 , 0.174 -Mean ..0.181 Crystallised Silicium.-Grey needles. 6 * "Prepared from ailicofluoride of potassium by means of sodium."-W ij h 1e r. t After drying the stopper. $ " Obtained by melting silicofluoride of potassium or sodium with aluminium ; the aluminium was then extracted wit,h hot hydrochloric acid and the oxide of sili-cium with fluoric acid."-W oh 1 er. 8 " This silicium was prepared from the silico%uoride of potassium or sodium by sodium and zinc and the lead (from the zinc) removed by nitric acid. Whetlier it was aft rwards treated with hydrofluoric acid I cannot say but probably SO. It was quite unchanged when heated in the vapour of hydrochlorate of chloride of silicium (passed by means of hydrogen).Probably it contained however like ail silicium reduced by zinc a trace of iron which appears when it is heated in chlorine. An experiment with another portion of such siliciu'm gave however so little iron that its quantity could not be determined."-Wohler. 194 KOPP ON THE SPECIFIC HEAT Experiments with Naphtha A. Glass 1. Temperature of the Air 19O.1. T. T? t? t. M. m. f. 9. x. sp. H. grms. grms. grm. grm. 0 0 0 0 53.8 21.1 20.83 18.53 26.94 2.395 1.955 0.431 0.651 0'168 52.6 21.0 20.74 18'52 26.975 I I? , 0.168 ?, ,) 51.9 21.0 20.66 18.53 26.975 , 1'935* ,) 62.3 21.0 20.72 18.52 26.98 , 0.168 )t 0.156 , , -Mean ..0.165 Fused 8ilicium.i Experiments with Naphtha A. Glass 1. Temperature of the Air 18O.9-18.7. T. T'. 6'. t. M. m. f. Y* x. sp. H. 49.0 0 20-5 0 20.24 0 18-40 0 26.97 417 grms. grms. 1.555 grm. 0.431 0.651grm- 0.142 50.5 49.7 50.8 20.7 20.6 20.7 20.43 20.27 20.43 18'52 18-42 18-52 26.96 26.965 26.94 , , , 1.145* ?? $ , ?? ? ,,,) , 0.139 0-136 0.136 _I_ Mean .. 0.138 * * * * * PARTIV.-Table of the Substances whose Specijc Heat has been experimentally determined. 81. The determinations given in the following summary are principally due to Dulong and Petit (D. P.) Nesmann (N.) Regnault (R.) and Kopp (Kp.). There are besides some of Person (Pr.) of Alluard (A.) arid the recent investigations of Pape (Pp.) are also included. By far the largest number of these determinations have been made by the method of mixture.A few only of the elements investigated by Dulong and Petit and some of the chemical compounds by Neumann were determined by the method of cooling. Where it is not otherwise stated in referecce to the temperature all determinations refer to tempera- 100°.and 0'tures between Where the determination has been made beyond these limits or where a more accurate statement of temperature is important it ia noticed. Where the same sub-stance has been repeatedly investigated by the same observer the result obtained for the purer preparation and in general the most certain result is taken. After drying the stopper. + Wohler had obtained it from Deville; it formed a cylindrical piece.OF SOLID BODIES. 195 In the following tables the chemical formula is given for each substance (the symbols used both here and subsequently when not otherwise mentioned referring to the numbers given in the last column of 5 2 as the most recent assumptions for the atomic weights) also the corresponding atomic weight and the atomic heat viz. the product of the specific heat and the atomic weight. 82. Elements and Alloys. Atomic Specific Atomic weight. heat. heat. .......... 0'055'1 D.P. 6.02 Ag .. .. 108 I .......... 0.0670 R. 6.16 .......... 0'0560 Kp. 6.05 A1 .. .. 27.4{ .......... 0'2143 R. 5.87 .......... 0.202 Kp. 5.53 A0 .......... 0.0814 R. 6.1 1 .. .. .. 75 { .......... 0.0293 D. P. 5-85 All ..197 .......... 0.0324 H. 6-38 Amorphous ...... 0.264 Kp. 2.77 Graphiioidal ...... 0.235 R. 2-56 B.. .. {Crystalline ...... 0'230 Kp. 2.51 .... 0*225-0%2 R. 2.45-2'86 11 .......... 0 0288 D. P. 6.05 Bi.. .. .. 210 .......... 0'0308 K. 6.47 0.0305 Kp. 6.41 I .......... Br .. 80 Between -78" and 20" . 0.0843 R. 6-74 I (Wood charcoal.. .... 0.241 R. 2.89 Gas carbon. ...... R. 0 204 Natural graphite Iron graphite '1: ...... 0.185 Kp. 2-22 .. 12 .... 0.202 R. c .. .. .... 0.1'14 Kp. 2.09 0.197 3.. ...... 2 36 ...... 0.166 Kp. 1-91) ...... 0.1469 R. 1.76 0'0567 It. (Diamond { .......... 112 Cd .. .. .......... 0'0542 Kp. 6.07 .. 68 8 0.1067 R. 6.27 .......... 0'0949 D. P. co ............ cu .. .. 63 4{ Hammered ...... 0.0935 R. 5.93 Heated ........ 0'0952 R. 6.04 .......... 0.0930 Kp. 5.90 .......... 0*1100 D. P. 6.16 Fe .. .. 66 { .......... 0'1138 R. 6 37 .......... 0.112 lip. 6-27 .. . . 200 Between -78" and -40" . . 0.0319 R. 6-33 7. .. .. 127 .......... 0.0341 B. 6.87 Ir.. .. .. 198 .......... 0.0326 R. 6-45 K.. .. .. 39 *1 Between -78" and 1 .... 0.1655 R. 6.47 Li.. .. .. 7 .......... 0.9408 R. 6.59 .. 24 1 .......... 0.2499 R. 6.00 Mg .. .......... 0'245 Rp. 5.88 Mn .. .. 55 .......... 01217 R. 6-69 Mo .. .. 96 ...... ... O.Oi22 K. 6.93 Na .. . 23 Between -34" and 7" .. 0.2934 R. 6.75 Ni .. .. 58.8 .......... 0'1092 R. 6.42 0s .. .. 199.2 .......... 0.0311 R. 6.20 KOPP ON THE SPECIFIC HEAT Atomic Specific Atomic weight.heat. heat. Yellow. between 13" and 36. .. 0.202 Kp. 6-26 .. 7" ..30. .. 0.1895 R.. 5'87 ..-21" ..7" .. 0-1788 Pr. 6.54 P .. .. ..31 [: ..-i8" ..10".. 0'1740 R. 5.39 .. 15" ..98. .. 0.1698 R. 5.26 ........ 0.0293 D.P. 6.06 Pb .. .. 207 6'50 {?!'..........0.0314 R. ..........0.0315 Kp. 0.52 Pd .. ..106.6 ..........0.0593 R. 6.32 .......... 0.0314 D.P. 6.20 Pt .. .. ..197.4 .... ..... 0'0324 R. 6.40 ..........0'0325 Kp. 6.42 Rh .. ..104.4 ..........0.0580 R. 6.06 ..........0.1880 D.P. 6.02 s .. .. .. 32 Rhombic. between 14" and 99" 0.1776 R . 5.68 { .. .. 17" ..45" 0.163 Kp. 5.22 ..........0.0507D.P. 6-20 .. ..122 .r..........0.0508 R. Sb 6.20 ........0 0523 Kp. 6-38 Amorphous. bet .-27" and 8" 0'0746 R. 6-92 Se.. .. . ..98" ..20° 0'0762 R. 6-05 ..-18" ..7" 0.0745 R. 6.92 Grapktoidal ......0.181 Kp. 6-07 Crystallised .... 0.165 Kp. 4.62 Si.. .. . 28 .... 0.i97-om R.4.68-5.01 Fuse$ ........0.135 KP. 3.86 ...... 0-156-0.175 R,.-4. -4.90 ........0.0514 D.P. 6-06 Sn .. .. 118 ........0.0562 R. 6.63 ........0'0548 Kp . 6.46 6.0'7 Te .. ..128 {........ ..0.0474 R. ..........00475 Kp. 6.08 TI.. .. .. 204 ..........0.0336 R. 6.85 w.. .. ..184 ..........0.0334 R. 6-15 ..........0'0927 D.P. 6-04 Zn .. .. 65 *2{ ..........0.0956 R. 6.23 ..........0-0932 Kp. 6.08 Alloys which only melt far above 100'. Bi Sn .. ..328 ..........0-0400R. 13.1 Ri Sn2 .. ..446 ..........0.0450 R. 20.1 Bi SnlSb .. 668 ..........0-0462R. 26.2 Bi SnsSbZn2 .. 698.4 ..........0.0566 R. 39.5 PbSb .. ..329 ..........0.0388 R. 12.8 Yb Sn .. ..325 ..........0'0407 K. 132 Pb Sn2 .. ..443 ..........0'0451 R. 20'0 83.Arsenides and Sulphides. CO AS^ ..208.8 Speis-cobalt ......0*0920 N. 19.2 As the locality of this mineral is not given. the formuIa and atomic weight are not certain . Metals replacing the cobalt can. however. have little influence on the atomic weight and the product . OF SOLID BODIES. 197 Atomic Specific Atomic weight. heat. heat. Ag2 S .. 248 Fused .... .... 0.0746 R. 18.5 CoAsS .. .. 166 Cobalt-glance .. .... 0.1070 N. 17.8 cui 9 .. .. 158.81Fu~ed .... .... 0-1212 R. 19.2 1Copper-glance ...... 0.120 Kp. 19.1 Fe As9 .. .. 163 Miepickel .. .... 0.1012 N. 16.5 ASS .. .. 107 Commercial .. .... 0.1111 N. 11.9 cos .. .. 90.8 Fused .... .... 0.1251 R. 11-4 9l .1Copper pyrites .. .... 0.1289 N. 11.8 Cnk Fea S .. I .. .. .... 0.131 Kp. 12.1 FeS .. .. 88 Fused .... .... 0.1357 R. 11-9 {rCinnabar .. .... 0.052 N. 12.1 HgS .. .. 232 .. .. .... 0-0512 R. 11.9 I .. .... 00517 Kp. 12.0 NiS .. .. 90.8 Fudh .... .... 0.1281 R. 11-6 Galena .... .... 0.053 N. 12-7 PbS .. 12.2 .. 239 { ...... .... 0-0509 R. 1 ?Y ** ** .... 0'0490 Kp . 11.7 SnS .. .. 150 Fused .... .... 0.0837 R. 12.6 f Zinc-blende .. .... 0'1145 N. 11.1 ZnS .. .. 97.24 .. .. .... 0'1230 H. 12.0 99 .. .... 0'120 Kp. 11.7 .. 648 {1 Magnetic pyrites ....0.1533 N. 99.3 Fe7 SB .. ...... .... 0.1602 R. 103.8 As. 53 . .. 246 Natural .... .... 0.1132 N. 2'7.8 BizS3 .. .. 616 1Artificial .. .... 0-0600 K. 31.0 SbiS3 ..340 Natural .... .... 0.0907 N. 30.8 Artificial .. .... 0*0840R. 28.6 /Marc;:te .. .... 0'1332 N. 16.0 Fe S2 .. .. 120 Iron pyrites .. .... 0.1275 N. 15'3 .. .... 0'1301 R. 15.6 .. .... 0.126 Kp. 15.1 160 {L NatuGl .. .... 0.1067 N. 17.1 MO52 .. .. .. .... 0.1233 R. 19.7 Y9 SnS2 .. .. 182 Bum musivum .... 0.1193 R. 21-7 84.Chlorine. Bromine. Iodine. and Fluorine Compounds. Ag C1 .... 143 *5 Fused ........ 0.0911 R. 13.1 CUCI .... 98.9 ...... 0'1383 R. 13.7 Hg Cl .... 235 -5 S;Ihmeh' ...... 0'0521 R . . 12.3 KC1 .. .. 74.6{ Fused ........ 0'1730 R 12.9 . ........0.171 Kp. 12.8 Li C1 .... 42.5 , ........ 0.2821 R. 12.0 .. .. .. ..0-2140 R. 12.5 Na C1 .. .. 68.5{ " .. .. .. 0'213 Kp. 12.5 Rdhk-sait' .. .. .. 0.219 Kp. 12.8 Rb C1 .. .. 120.9 Fused .. .. .. .. 0'112 Kp. 13.5 N H4C1 .. .. 53 .5 Crystallised .. .. .. 0.373 Kp. 20.0 Ba C12 .. .. 208 {Fused .. .. .. 0.0896 R. 18.6 L .. .. .. .. 0'0902 Kp. 18.8 -4 Ca C12 .. .. 111 .... .. .. .. 0'1642 R. 18.2 HgCl2 .. ...ned .. .. .. 0-0689 R. 18.7 .. .. .. 0'0640 Kp. 17.3 MgClz .. .. .. .. 0-1946 R. 18.5 .. .. .. 0.192 Kp. 18.2 MnC12 .. .. 126 .... .. .. .. 0.1425 R. 18.0 Pb Cl2 .. .. 27s .... .. .. .. 0.0664 B 18.5 Bn Clz .. .. 189 .... .. .. ..0.1016 R. 19.2 KOPP ON THE SPECIFIC HEAT Atomic Specific Atomic weight. heat . heat.Sr Clz .... 158 6 Fused ...... .. 0'1399 R. 19.0 Zn Clz 136 -2 .... .. 0-1362 R. 18.6 Ba cl2.iH. o ::2.14 C~stall&d .... .. 0.171 Kp. 41.7 CaCIz.6H,O .. 219 Between -21Oand 0" .. .. 0.345 Pr. '75.6 Zn K2C1..... 285 -4 Crystallised .... .. 0.152 Kp. 43.4 Pt K2 ClG .. 488 *6 .. .... .. 0.113 Xp. 55.2 Sn KzCI6 .. 409 -2 .. .... .. 0'133 Kp. 54.4 Cr2 CIS .... 317 *4 .... .. 0.143 Kp. 45.4 Ag Br ....188 Fused) ...... .. 0.0739 R . 13.9 K Br .... 119.1 ........ .. 0.1132 R. 13.5 NaBr .... 103 ......... .. 0.1384 R . 14.3 Pb Brz .... 367 ........ .. 0.0533 R. 19.6 AgI .... 235 ........ .. 0.0616 R. 14.5 CUI .... 190.4 ........ .. 0.0687 R. 13.1 327 Powder ...... .. 0.0395 R. 12.9 PIr : ::166.1 Fiwed ...... .. 0.0819 R. 13.6 NaI ....150 ........ .. 0.0868 R. 13.0 HgI2 .... 454 ........ .. 0.0420 R. 19.1 PbI2 ....461 ........ .. 0.0427 It. 19.7 Fluor-spar .... .. 02082 N. 16.2 CaF1. .... z3 { 1) .... .. 0.2119 R. 16.8 .... .. 0.209 Kp. 16 3 A1 Na. F16 .. 210.4 Cryoiite .... .. 0.238 Kp. 50.1 cu20 ....142 . Red copper ore .. .. 0.1073 N . 15.3 .... .. 0.111 Kp. 15.9 18 1Ice be&een .21" and ..2" .. 0-450 Pr. 8.6 HLO .... 78" 1) 0" .. 0.474 R. 8.5 Y# Desains found the specific heat of ice between .20" and 0" to be 0.513; Person. between .20" and 0' = 0.504; Hess. between .14' and 0" =0.533. Person is of opinion that ice even somewhat below its meiting.point. between 2'. and 0.. absorbs heat of fusion. cu 0 .... ...... ...... .. .. .. 0.137 N. .. 0.1420 R.10.9 11.3 Hg 0 Mg 0 Mn 0 Ni 0 ...... {Corn ial .. .... 71 ...... Feebly ignited .. Fused .... .... 216 Crptallino .. .. .... 40 1.. : : .... 74.8(st rongly ignited .. .. .. .. .. .. .. .. .. .. .. .. 0.128 Kp. .. 0.049 N. .. 0.0518 R. .. 0*0530 Kp. .. 0276 N. .. 0.2439 R. .. 0.1570 R. .. 0 1623 R. .. 0.1588 R. .. 0-0509 R. 10'2 10.6 11.2 11.4 11.0 9.8 11.1 12.1 11.9 11.4 Pb 0 Zn 0 .... .. .... 81*2{ ............ Mg 0 .H20 .. 68 Brucite .... Fez O4 .... 232 #* Mg A12 04 142 *8 Spinelle .. {Magytic iron ore ¶I MghFe~Cr#Al~04*196 Chrome iron ore .. .. .. .. .. .. .. .. .. .. .. 0.0512 R. .. 0.0553 Kp. .. 0*132 N. .. 0.1248 R.. .. 0312 Kp. .. 01641 N. .. 0.1678 R. .. 0.156 Kp. ..0.194 Kp. .. 0.159 Kp. 11.4 12.3 10.7 10.1 18.1 38.1 38.9 36.2 27.7 31.2 The preparation contained carbonate of sodium.OF SOLID BODIES. 199 Atomic SpecXc Atomic weight. heat. beat. 0.1972 N. 20.5 t. .. .. 102.8 {Sapphire .. .. .... .. .. .. 021'73 R. 22.3 .. .. 198 Opaque .. .. .. .. 0.1279 R. 25.3 .. .. 69-8 Fused .. .. .. .. 0.2374 R. 16.6 .. .. 468 .... .. .. .. 0.0605 R. 28.3 ........ .. 0.196 N. 29'9 .. 0.1796 R. 27.4 .... 152.4 i........ Crjstalline .... .. 0.177 Ep. 27.0 Artificial. feebly ignited .. 0.1757 R. 28.1 .. strongly ignited .. 0.1681 R. 26.9 I .... 160 Specular iron .... .. 0-1692 N. 27.1 .... ..0.1670 R. 26.7 I " c s* .... .. 0.154 Kp. 25.1 27.4 Fe5 Ti3 0 .. 165*5{ Iserine .. ** ** .. 0.1762 N. ...... .. 0.177 Kp. 27.6 Sb20. .... 292 Fuk ...... .. 0'0901 It. 26.3 Mn2 O3.H2 0 ..176 Manganh .... .. 0.176 Kp. 31.0 Mn09 .... 87 Pjrolusite .... . 0-159 Kp. 13-8 .. 0.1883 N. 113 .... 60 iQu:: Si02 : : 1 .. 0.1913 R. 11-5 1 ........ .. 0.186 Kp. 11.2 13.2 Sil Zri O2 .. 90*8{ Zircon ** '* ** .. 0'1456 R. ........ .. 0.132 Kp. 12.0 rCassiterite .... .. 0.0931 N . 14.0 0.0933 R. 14.0 4. .... .. 0.0894 lip. 13.4 .... .. 0.1716 R. 14.1 .... .. 0.1724 N. 141 .... .. 0.1703 R. 14.0 .... .. 0.157 Kp. 12.9 .... .. 0.161 Kp. 13.2 M003 .. .. 144 {Fused .. .... .. 0.1324 R. 39.1 22.2 .... .. 0.0i98 R. 18.5 woa .... 252 {Pulverulent .... .. 0.154 '? Kp. .... 0.0894? Ep. 20.7 a. 86.Carbonates and Silicates. .. .. 0.2162 R. K2C03 .... 138*2{Fused .. .. .. .. .. 0206 Icp. 29.9 28.5 9) .... .. 02728 R. 28.9 9' ** 8a2 c o3 .. 106 f .... .. .. .. 0246 Kp. 26.1 Rb2 C O3.... 230-8 .. .. .. 0.123 Kp. 20.4 Baa03 .... 197 {Wrtherite .. .. .. .. 0-1078 N. 21.2 .... .. .. .. 0-1104 R. 21.7 .. .. .. 0.2046 N. 20.5 .. .. .. 0.2086 R. 20.9 .. .. .. 0.206 Kp. 20.6 .. .. *. 0*2018N. 20.2 .. .. .. 02085 R. 20.9 .. .. .. 0.203 Kp. 20.3 .. .. 0-2161 N. 19.9 .. .. ..0-2179 R. 20.0 .. .. .. 0206 Kp. 19.0 .. .. .. 0.182 N. 21.1 Pe GO3 .... 116 {spathiciron .. .. .. 0.1934 R. 22.4 The minerals investigated doubtless contained part of the iron 200 HOPP ON THE SPECIFIC HEAT replaced by metals of lower atomic weight. The atomic weight and the product assumed above are somewhat too great. Atomic Specific Atomic weight.heat. heat. F&Mn*MgACO3 112.9 Spathic iron ......0.166 Kp. 18.7 Mg? Fep C O3 .. 91.1 Magnesits ......0.227 N. 20.7 pb o3.... 267 {Cerussite ...... 0,0814 N. 21.7 >3 ...... 0.0791 Kp. 21.1 Regnault found for precipitated carbonate of lead still con- taining water the specific heat 0*0860. SrC O3 .... 147*6{ Strontianite ...... 01445 N. 21.3 Artificial ...... 0.1448 R. 21.4 Ca Si 03.. .. 116 Wollastonite ...... 0.1'78 Kp. 20-7 ce Mg+ si o3 .. {Diopside from Tyrol .... 0*1906N. 20-6 )? ...... 0.186 Kp. 20.1 Cu Si OPHo0 .. 157 *4 Dioptase ......0.182 Kp. 28.7 Olivine ........0.189 Kp. 27.6 Mgg Fe&Si04 145.8ICrysolite ...... 0.189 Kp. 27.6 ......0,2056 N. 30.0 99 Adularis ...... 0.1861 N. 1039 A12 K2 Si6Ole ........ 0.1911 N. 106.4 ...... 0.183 Kp. 101'9 ........ 0,1961 N. 102.9 812 Nh Sic 016 .. ........0-190 Kp. 99.7 87. Borates Molybdates Tungstates Chromates and Sulphates. K B O2 ... 82 Fused ........ 0.2048 R. 16.8 NaB02.e .. 65.9 ..........02571 R. 16.9 Pb B2 04.. .. 292.8 .......... 0.0905 R. 26-5 PbB407.. ..362.6 .......... 0.1141 R. 41.4 K2 B4 0 ..233'8 ..........0-2198 R. 51-4 0.2382 R. 48.0 *' ** Nn,BqOf ..201.6 ') *' :'...... 0.229 Kp. 46-2 Na,B4 0p10H2 0 381 -6 Cr&dliied borax ....0.385 Kp. 14439 Yb Mo O4 .. 367 Yellow leadore .... 0.0827 Kp. 30.4 Ca W 04.. ..288 Scheelits ...... 0.0967 Kp. 2'7.9 28.2 FeS Mng W O4..333 .4(Tungskn '' ** .* 0.0930 Kp. ...... 0.0978 .R. 29.7 29 The locality of the wolfram investigated hy Regnault is not known and the composition uncertain.But the change in the ratio in which iron and manganese are present in the mineral alters little in the atomic weight. Pb Cr 04. .. 323.4 Fused ........ 0.0900 Kp. 29'0 g2 Cr 04.. ..194 .4{ Uryatallieed ...... 0.1851 R. 36-0 9) ...... 0.189 Kp. 36.7 ...... 0.1894 R. 55.8 K Cr2 O7 ..294*6{ " ...... 0.186 Kp. 59.8 EHS01 ..136.1 , ...... 02M Kp. 33.2 OF SOLID BODIES. 201 Atomic &&iffC Atomia weight. heat. heat. .... 01901 R. 33.1 34.1 &SO4 .. .. 174 *2{E:;ztG;;d: .... 0.196 Kp. .... 0.2312 R. 328 Na2S O4.. .. 142 {E:;:;~ied : .... 0.227 Kp. 32.2 N%Ha s 04 .. 132 .. .... 0.350 Kp. 46.2 77 Heavy spar .. ....0.1058 N. 25.4 Bas O4 ....233 { .. .. .. 0.1128 R. 26-3 I .. .... 0.108 Kp. 25.2 Calcined msum .... 01966 R. 26.7 CaS 0 .. ..136 Anhydrite .. .... 0.1854 N. 25.2 " .. ....0.1'78 Kp. 24.2 cuso. .. ..15904 So1id)'pieces .... 0.184 Pp. 29.3 MgS04 .. ..120 {Dehydrated sali' .... 0.2216 R. 26.6 Solid pieces .. .... 0.225 Pp. 27.0 MnS0. .. .. 151 .. ....0.182 Pp. 27'5 ArtiH)cial .. .... 0.0872 R. 26.4 PbS04 .. .... 0.0848 N. 25'7 A.rti:cial .. .... 0-0827 Kp. 25.1 .... 0.1428 R. 26.2 SrS04 .. .. 183.6 Ccelestine .. .... 0.1356 N. 249 .. .... 0.135 Kp. 248 ZnSOA .. .. 161 '2 Coarse wowder .. .... 0.174 Pp. 28.0 CUSO .H2 0 .. 177 -4 Pulverdent ......0.202 35.6 Mg SO4 .H2 0 .. 138 Coarse powder.......0.264 36-4 Zn so4 .H20 .. 179 -2 Solid pieces ......0.202 36.2 ...... 0.2728 46-9 Ca SO .2 H20 .. 172 {G~~sum ......0.259 446 CUSO1 .2 H2 0.. 195 *4 Pulverulent ...... 0.212 41.4 Zn SO4 .2 H2 0.. 197 *2 Solid pieces ...... 0.224 44.2 FeS04.3H20.. 206 ...... 0.247 50.9 ...... 0.285 71.1 Cu SO .5 H20.. 249 -4{ ......0.316 78.8 ...... 0.323 77.8 MnS04.5H20 241 { :i .. ...... 0.338 81.5 NiSO .6H20.. 262.8 .. ...... 0.313 82.3 CoSO .'7HZO .. 280.8 .. ...... 0.343 96.4 ......0.346 96.2 FeS04.7H20 .. 278 { " ...... 0.356 99.0 ...... 0.362 89.1 " Mgb04 .'7H20. 246 { $9 ...... 0.407 100.1 93 ZnS04.'7H20 . 287-2{ ...... 0-347 Kb. 99.7 ...... 0.328 Pp. 942 MgK2S2Os .6H20 402 -2 ...... 0.264 Kp. 106.2 NiK2S20s.6H20 437 ...... 0245 Kp. 107-1 ZnIC2S20s.6E20 443*4 ......0-270 Kp. 119.7 A12K2S4016 .24HZO 949 alum .... 0.371 Kp. 352.1 Cr2K2S4OI6.24H20 998 -6 chrome alum .. 0.324 Kp. 323.6 88.Arseniates. Phosphates. Pyrophosphates and Metaphosphales. Nitrates. Chlorates. Perchlorates. and Permanganates. K As O3 .... 162 -1 Fused ........ 0.1563 R. 25.3 EH2 As04 .. 180.1 Crystabed ...... 0.175 Ep. 31.5 Pb3As2Og .. 899 Fused ........0'0728 R. 65-41 Ag3P04.... 419 Pulverulent ...... 0*0896?Kp. 375 KHzP04 136.1 Crystalbed ...... 0.280 Kp. 283 Nar,HP0 .12HiO 358 Between -21" and 22" .. 0408 Pr. 146-1 202 KOPP ON THE SPECIFIC HEAT The determinzth-ri of' +he specific heat refers to the crystallised salt. For the hed and afterwards solidified salt Person found the specific heat between the same range of temperature con-siderably greater = 0.68 to 0.78; but the mass obtained by solidifying the fused salt gradually alters (it becomes crystallised again) with increase of volume which is very considerable when the fused salt is allowed to cool very rapidly.Atomic weight. Specificheat. Atomic heat. Pb3 pz 0s K4P207.. .. 811 .. 330.4 Fised .. ... .. .. .. .. .. 0.0798 R. .. 0.1910 R. 64.7 63.1 Na4P207 .. Pb2 p2 07 .. Na P O3 .... Ca P2 06 .... AgN03 .... 266 588 102 198 170 , .. , .. , ..) .. .... .. .. .. .. .. .. .. .. .. .. .. .. .. 0.2283 R. ,. 0.0821 R. .. 0'217 Kp... 0.1992 R. .. 01435 R. .. 0.2388 R. 60.7 48.3 22.1 39-4 24.4 24-1 KN03 .... 101'1 E;Na&N03 .. 93 Fused* .. NaN03.. .. NzH403.. .. BaNaOfj.. .. PbN2Ofj.. .. SrN206.... EC103 .... Baa206.H20 * KCl O4 ... K Mn 04 .. .. .. .. ...... 85 ...... Crystallised .. 80 ..,9 r 211-6 .. .. 122.6{F~sed .... Crystallised .. 322 ..I 138.6 , .. 158.1 , .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. 0.22'7 Kp. ,. 0.232 Kp. .. 0.235 Pr. .. 0-2782 R. .. 0.256 Kp. .. 0.257 Kp... 0.455 Kp... 01523 R. .. 0.145 Kp. ,. 0110 Kp. .. 0181 Kp. .. 0.2096 R. .. 0194 Kp... 0-157 Kp... 0.190 Kp... 0.179 Kp. 22.9 23.5 21.9 23.6 21.8 21.8 36.4 39.8 37'9 36-4 38-3 25.7 23-8 50.6 26.3 28-3 89. So-called Organic Compounds. Hg c2N2 .. 252 Crystallised cyanide of mercury 0*100 Kp. 25.2 znK2C4N4 .. ...... b9.6 76.7 ...... 118.3 42.2 The sperific heat between 18' and 43' was found = 0.194; between 18O and 50' = 0.277. C1,H8 .... 128 Between -26" and 18O .. 0-3096 A.39-6 * Obtained as maas of constant meltingpoint (alQO.8) by fusing equivalent quantities of nitrate of pot-and nitrate of eodo. 66'.and20'between0-3208and20,and 0'between OF SOLID BODIES. 203 The specific heat of naphthalene was fwd to be 0.3208 Atomic Specific Atomic weight. heat. heat. The first formula is that of one constituent of bees'-wax cerotic acid; the second is that of the other palmitate of melissyl. With reference to the numbers found for the specific heat of bees'-wax at higher temperatures compare the last remark in $77. Crystallised cane-sugar ..0.301 Kp. 102.9 Cl2H=Ol1 .. 342 { Amorphous cane-sugar .. 0.342 Kp. 117.0 C6H1406 .. 182 Mannite ......0-324 Kp. 69.1 C4H6o4.... 118 Succinic acid ......0.313 Kp.36.9 C4H606.... 150 Tartaric acid ...... 0.288 Kp. 43.2 C4H606.H20 .. 168 Racemic acid ......0,319 Kp. 53.6 C2H2Ba O4 .. 22'7 Formate of Sariurn ....0.143 Kp. 32.5 C2K2O4 .H20 .. 184 -2 Neutral oxalate of potassium.. 0236 Ep. 43.5 C4H K O8.2 H20 254 -1 Quadroxalate of potassium ..0.283 Kp. 71.9 C4 H5 K O6 .. 188 -1 Acid tartrate of potassium .. 0.25'7 Kp. 48.3 C4H4Nn.K06, 4H20 282'1 Seignette salt ...... 0.328 Kp. 925 C8HloCaOlo.8H20 450 Acid malate of calcium ..0.338 Kp. 152.1 The preceding tables contain the material obtained experi-mentally which serves as subject and basis for the subsequent considerations on the relations of the specific heat of solid bodies to their atomic weight and composition. PARTV.-On the Relations between Atomic Heat and Atomic Weight or Composition.90. I discuss in the sequel the regularities exhibited by the atomic heats of solid bodies the exceptions to these regularities and the most probable explanation of these exceptions. With regard to the views which are here developed much has been already expressed or indicated in former speculations; iii this respect I refer to the first part of this paper in which I have given the views of earlier inquirers as completely as I know them and as fully as was necessary to bring out the peculiar value of each. It is unnecessary then to refer again to what was there given; but I will complete for individual special points what is to be remarked from an historical point of view. But before discussing these regularities the question must be discussed whether the atomic heat of a given solid substance is KOPP ON THE SPECIFIC HEAT essentially constan$ or varies materially with its physical con-dition.It depends on the result of this investigation how far it may with certainty be settled whether the general results already obtained are of universal validity or whether exceptions to them exist. The specific heat of a solid body varies somewhat with :t I s tem-perature but the variation of the specific heat with the tempera- ture is very small provided the latter does not rise so high that the body begins to soften. Taking the numbers obtained hy Regnault for lead by Dulong and Petit by Bede and by Bystriim for the specific heats of several metals at different temperatures the conviction follows that the changes of specific heat if not of themselves inconsiderable are yet scarcely to be regarded in comparison with the discrepancies in the numbers which different observers have found for the specific heat of the same body at the same temperature.At temperatures at which a body softens the specific heat does indeed vary considerably with the temperature (compare for example 5 77); but these numbers as containing already part of the latent heat of fusion give no accurate expression for the specific heat and are altogether useless for recognising the relations between this property and the atomic weight or composition. Just as little need the small differences be considered which Regnaul t found for a few metallic substauces according as they were hammered or annealed hard or soft.For dimorphous varieties of the same substance even where there are considerable differences in the specific gravity the specific heats have not been found to be materially differeot (see FeS, 4 83; Ti 0, 5 85 ;CaCO, 86). The results obtained with these substances appear to me more trustworthy than those with graphite and the various modifications of boron and silicium which moreover have given partly the same specific heat for the graphitoydal and adamantine modification of the same element. What trustworthy observations we now possess decidedly favour the view that the dimorphic varieties of the same substance have essentially the same specific heat.91. It has been surmised that the same substance might have an essentially different specific heat in the amorphous and crystal- line states. I believe that the differences of specific heat found for these different conditions depend to by far the greatest extent upon other circumstances. OF SOLID BODIES The tables in 5 83 to $ 89 contain a tolaable nmnber of sub- stances which have been investigated both akr b&ng melted and also crystallised ;there are no such differences in the numbers as to lead to the supposition that the amorphous solidified substance had a different specific heat to what it had in the crystallised state. No such influence of the state has been with any cer- tainty shown to affect the validity of Dulong and Petit’s or of Neumann’s law.I may here again neglect what the deter- minations of carbon boron or siliciiim appear to say for or against the assumption of a considerable influence of the amorphous or crystalline condition on the specific heat. Regnault found (5 85) that the specific heat of artificially prepared (uncrystalline ?) and crystallised titanic acid did not differ. According to my investi- gations ($ 48) silicic acid has almost the same specific heat in the crystallised and in the amorphous condition. In individual cases where the specific heat of the same sub-stance for the amorphous and crystallised modification has been found to be materially different* it may be shown that foreign influences affected the determination for the one condition.Such influences are especially 1. That one modification absorbed heat of softening at the temperature of the experiment ; that is doubt- less the reason why the specific heat of yellow phosphorus was found to be considerably greater at higher temperatures than that of red phosphorous but not at low temperatures (compare 5 82) that the specific heat of amorphous cane-sugar was found to be decidedly greater than that of the crystallised variety ($ 78) and according to Regnault’s opinion also that the specific heat of amorphous selenium between 80’ and 18’ was found much greater ( = 0.103) than that of the crystalline while for lower tempera- tures there was no difference in the specific heats of the two sub-stances (§ 82). 2. That in heating one modification its transition into the other is induced and the heat liberated in this transition makes the numbers for the specific heat incorrect; in 5 33 I have discussed the probability that this circumstance in Regn ault’s first experiments with sulphur gave the specific heat much too * De la Rive and Marcet (Ann.Ch. Php. [2] lxxv 118) found the specific heat of vitreous to be different from that of opaque arsenious acid and considered the fact to be essential; but their method was not fitted to establish such a digerence. Pap e ’a view too (Pogg. Ann. cxx 341 and 342) that it is of essential importance for the apecific heat of hydrated sulphatea whether the salts are crystallized or not does not appear to me to be proved by what he has adduced.VOL. XIX. Q KOPP ON THE SPECIFIC HEAT high and it is pomible that it was also perceptible in the above- mentioned experiments with amorphous selenium. 3. That in immersing heated porous bodies in the water of the calorimeter heat becomes free (compare 5 19) ; I consider this as the reason why Regna ult found the specific heat of the more porous forms of carbon so much greater than that of the more compact forms (compare 36); and Iiegnnult himself sees in this the reason why he found the specific heat of the feebly ignited and porous oxides of nickel and of iron greater than that of the same oxides after stronger heating (compare $ 85). From the importance of this subject for the considerations to be afterwards adduced I have here had to discuss more fully what differences are real and what are only apparent in the num- bers found for the specific heat of one and Ihe same substance.Even if the apparent differences are often considerable their importance diminishes if allowance is made for tbe foreign influence which may have prevailed. In many cases on the other hand a body in totally different modifications has almost exactly the same specific heat if these foreign influences are excluded. It may then be said that from our present know-ledge one and the same body may exhibit small differences with certain physical circumstances (temperature different degree of density) but never so great that they may he taken as an explana- tion why a body decidedly and undoubtedly forms an exception to a regularity which might have perhaps been expected for it-pro-vided that the determination of the specific heat according to which the body in question forms an exception is trustworthy and kept free from foreign influences.92. Among the regularities in the atomic heat of solid bodies that found by Dulong and Petit for the elements stands fore- most. A glance at the atomic heats of the so-called elements collated in 0 82 shows that for by far the greater number the atomic heats are in fact approximately equal. But the differences in the atomic heats even of those elements which are usually regarded as coming under Dulong and Petit’s law are often very considerable even when the comparison is limited to those which are most easily obtained in a pure state and even if numbers are taken for the specific heats which give the most closely agreeing atomic heats.Regnault * sought an explana-Q Ann. Ch. Phye. [2] lxxiii 66 and [3] xlvi. 257. OF SOLID BODIES. tion of the differences of the atomic heats of th elements in the circumstance that the latter could not be investigated in comparable conditions of temperature and density ;further that the numbers for the specific heat as determined for solid bodies contain besides the true specific heat (for constant volume) also the heat of expatision. As specific heat we can indeed only take the sum of the heats necessary for heating and for expansion. But it is not yet proved that the products of the first quantity (the specific heat for constant volume) and the atomic weights would agree better than the atomic heats now do ;it is only a supposition and even the very contrary may be possible with individual substances.Temperature has an influence on the specific heat of solid bodies and to a different extent with different bodies. Even in this respect also all meaiis are wanting by which the different tem- peratures at which bodies are really comparable can be known and a comparison made of their atomic heats. The utmost pos sible is to determine the specific heat at such a distance from the melting point that. latent heat of softening can have no influence. It is impossible to say with certainty whether the atomic heats of bodies compared at other temperatures than those which are nearly identical (ranging about 90' on each side of 10") will show a closer agreement.It is not probable. Changes in the specific heat of solid bodies so long as they are unaffected by heat of softening are small in comparison with the differences which the atomic heats of individual elements show. And it is well worth consideration that individual elements (phosphorus and sulphur e.g.) at temperatures relatively near their melting points have not materially greater specific heats than other elements (iron and platinum for example) at temperatures relatively distant from their melting points but on the contrary considerably smaller. As regards the influence of density on the specific heat it is undoubtedly certain that the latter may somewhat vary with the former; but it is equally so that in all cases in which sub-stances of undoubted purity were examined and the sources of error mentioned (8 91) excluded this variation is too inconsider- able to give an adequate explanation of the differences of the atomic heats found for the various solid elements.I need not here revert to the considerations developed in $5 90 and 91 as to how far a difference in the physical condition of a solid suhstance exercises an essential influence on its specific heat ; for whatever view may be held with reIerence to this influence Q.2 EOPP ON THE SPECIFIC HEAT and generally with reference to the circumstances which alter the specific heat of a substance and therewith the atomic heat this is certain that there are individual elements whose atomic heat is distinctly and decidedly diffaent from that of most other elements.Such elements are from 5 82 first of all boron carbon and silicium. The decision of the question whether these elements really form exceptions to D ulong and Petit’s law presupposes hesides a knowledge of their specific heat a knowledge of their atomic weight also. There can be no exceptions to Dulong and Petit’s law if regardless of anything which may be in opposition to it the principle is held to that the atomic weights of the elements must be so taken as to agree with this law. As a trial whether this law is universally applicable the atomic weights ought rather to be taken as established in another manner.It may be con- fessed that the determination of the true atomic weights by chemical and physico-chemical investigations and considerations is still uncertain and many questions are still unanswered the settlement of which may influence that determination. But there seems now to be no more trustworthy basis for fixing the atomic weights of the elements than that of taking as the atomic weights of the elements the relatively smallest quantities which are contained in equal volumes of their gaseous or vaporous com-pounds or of which the quantities contained in such volumes are multiples of the smallest numbers; and no better means appears to exist for determining the atomic weights of those elements the vapour-densities of whose compounds could not be determined than the assumption that in isomoryhous compounds the quan- tities of the corresponding elements are as the atomic weights of the latter.On this basis and using this means the numbers for the atomic weights have been determined which are contained in the last column of the Table in 5 2 and are used in 9 82 et seq. The atomic weights B = 10.9 C = 12,Si = 28,cannot be changed for others. That the atomic weights of tin and silicium are as 118 to 28 is further proved by the isomorphism of the double fluorides. But to these atomic weights correspond atomic heats which are far smaller than those found for most other elements. From the chemical point of view it is inadmissible to take the atomic weights of boron carbon and silicium* in such a manner as to make their * For Regnault’s observation whether considering the specific heat which he found for silicium its atomic weight is to be so taken that silicic acid contair.8 OF SOLID BODIES.209 atomic heats agree with Dulong and PetikJw hw. In any case these three elements form exceptions to Dulong and Petit's law. The sequel will show that this is the case with many other elements. 93. In many compounds the regularity is observed that by di- viding their atomic heat by the number of elementary atoms con-tained in one molecule of the compound a quotient is obtained which comes very near the atomic heat of most of the elements -that is 6.4. This is found in the alloys enumerated in 0 82 and also in a great number of compounds of definite proportions.A few of the most important cases may be given here. For lgS2 srnaltine CoAs (compare 0 83) this quotient is -= 6.4; 3 for the chlorine-compounds RCl and aCl* the mean of the 12.8 -6.4. atomic heats given in $ 84 is 12.8 and the quotient -2 Of the chlorine-compounds RCI, the mean atomic heat of all 18.5 the determinations in $ 84 is 18.5 and the quotient -= 6.2. 3 It is also very near this value in the double chlorides ; in ZnK,Cl it is c4= 6.2 for &K,Cl6 (the mean of the determinations of 7 PbK,Cl and SnK,C16) it is E8= 6.1. For bromine-compounds 9 RBr (both here and in the following examples the means are taken of the determinations in 5 84) '39= 6.9; for PbBr,, 2 19-6 13.4 -= 6.5; for iodine-compounds RI and aI,-2 = 6.7, 8 19.4 and for the iodine-compounds BL,,-= 6.5.3 But this regularity though met with in many compounds is by uo means universal. The oxygen-compounds of the metals correspond to it in general the less the greater the number of oxygen-atoms they eontain as compared with that of metal. The 2 atoms of silicium to 6 of oxygen compare Ann. Chim. Phye. [S] v. Ixiii 30. For Scheersr's remark that according to the most probable specific heat of silicium its atomic weight must be taken BO that for 1 atom of silicium there are 3 atoms of oxygen compare Poggendortl? s Annalen vol. cxviii p. 182. * In the sequel R stands for a uni-equivalental and B for ti polyequivalmtal atom of a metal. !!.? quotient 210 ROPP ON THE SPECXFIO HEAT mean atomic heat d t%e oxides -ROin 5 85 is 11.1 and the = 5.6.The quotient for the oxides R,O and 2 a,O (even excluding the determinations of alumina and boracic 27.2 acid) is only -= 5.4; for the oxides go (even excluding 5 the determinations for silicic acid and zircon) only E7= 4.6; 3 for the oxides go3,the mean of Regnaul t’s determinations only 18.8 -4 = 4.7. Still smaller is the quotient for compounds which contain boron in addition to oxygen (e.g.for the compounds R RO (compare Q 87) it is only K8= 4.2; for boracic acid B,O, it 4 is cnly - 3.3) ; also for compounds which contain sili-5 11.3 -cium in addition to oxygen (it is -3.8 for eilicic acid, 3 Si 0, compare 85) or which contain oxygen as well as hydrogen (for ice H,O it is only E!? = 2 9” compare 5 85) or which 3 contain hydrogen and carbon besides oxygen (e.$* it is only 36.9 = 2.6 for succinicacid C,H,O, compare SQ).Wemay 14 state in a few words which are the cases in which this quotient approximates to the atomic heat of most elements and which the cases in which it is smaller. It is near 6.4 in those compounds which only contain elements whose atomic heats corresponding to Jk Considering the atomic heat of liquid water to be 18 Gtarnier (Compt. rend. xxxv. 278) thought that the quotient obtained by dividing the atomic weight by the I# number of elementary atoms in one atom of the compound = 6 came near t,he atomic heat of the elements. But it requires no explanation to show that in a compa-rison with the atomic heats of solid elements and solid compounds that atomic heat must be taken for the compound H20which is obtained from the specific heat of ice and not from that of water.Barni er is not alone in his error which is rather to be ascribed to the circumstance that formerly in considering the influence of composi-tion or the specific heat of compounds solid and liquid bodies were regarded as comparable in respect of their specific heat. Hermann more especially (Nouveaux Mimoires de la Societ6 des Naturalistes de MOSCOU, vol iii p. 137) compared liquid water with solid Compounds as did also Schroder (Pogq.Ann. lii 279) ; SO likewise did L. Gmeiin in an early discussion of this subject (Gehler’s Physicalische Wor{erbuch neue Bearbeitung,’ vol.is. p. 1942) while he subsequently (Handbuch der Chemie 4 Ad. vol. i p. 220) more correctly compared the specific and the atomic heat of ice with that of other solid compounds. OF SOLID BODIES. Dulon g and Petit’s law are nearly equd to 6.4; it is smaller in compounds which contain elements not coming under D ulong and Petit’s law and having a much smaller atomic heat than 6.4 and which are recognised as exceptions to this law either directly if their specific heat has been determined for the solid state (compare 9 92) or indirectly if it be determined in the manner to be subsequently described. 94. The determinations of specific heat given in 5 5 83 to 89 contain the proofs hitherto recognised for the law that chemically- similar bodies of analogous atomic constitution have approximately the same atomic heat; and a considerable number of new ex-amples of the prevalence of this regularity are given by my de-terminations.The groups of analogous compounds need not again be collated as Neumann has done for a smaller and Regnault for a larger nnmber of groups and for individual ele- ments contained in them. What I will here discuss is the preva- lence beyond the limits of our previous knowledge of the regu- larity that compounds of analogous atomic constitution have approximately the same atomic heat. To this belongs first the existence of this regularity in the case of chemically similar bodies which exhibit an analogy of atomic constitution when their formulae are written with the atomic weights admitted in recent times for the elements but which could not be recognized so long as the equivaleuts of the elements were talien as a basis or the formula written as by Regnault with the use of the so-called thermal atomic weights.The approximate equality of the atomic heats of analogous nitrates and chlorates of the alkalies for example had been already observed. The same character the haloid is ascribed both to carbonates and to silicates ; but as their formulz were formerly written an analogy in the composition of chlorates and nitrates or carbonates and silicates could not be assumed. But salts of these four different classes as well as arseniates and metaphos- phates have analogous atomic constitutions if we assume the recent atomic weights.The same salts have then also approxi- mately equal atomic heats. We get the atomic heat Of chlorate of potassium KClO, 0 88 .. .. M* 24.8 , the nitrates RNO, in 88 ..... . .. .. M 23.0 * M signifies the mean of a11 determinations. KOPP ON THR SPECIFIC HEAT Of metaphosphate of sodiuni NaPO, 5 88 .... 22.1 ..arseninte of potassium KAsO, 5 88 ...... 25.3 ..the carbonates aCO, 5 86 .......... M 20.7 ..the silicates &SiO, $ 86 ............ M 20.5 The differences in these approximately concordant atomic heats are partly essential and explainable. 1 shall return to this point (0 95)-According to the more recent assumptions for the atomic weights certain perchlorates permanganates and sulphates have an analiigous atomic composition and these salts have also approxi- mately equal atomic heats; this has been found to be- For perchlorate of potassium KClO, § 88 ....26.3 , permanganate of potassium KMnO, $ 88 .. 28.3 .. the sulphates RSO, named in 5 88.. .. M 26.1 But approximate equality in the atomic heat is found not only in such compounds of analogous chemical composition as have similar chemical character but also in such as have totally dissimilar chemical character. The chemical character of ferroso-ferric oxide (magnetic iron ore) is quite different from that of neutral chromate of potassium. Ferric oxide and arsenious anhydride have a chemical character totally different from nitrates or arseniates or bodies of similar constitution.But for the first-named and for the last-named compounds as respectively Compared with each other there is analogy in chemical composition and approximate equality of atomic heat. The atomic heat has been found to be- For magnetic iron ore Fe304 § 85 ...... M 37*7 , chromate of potassium K,CrO, 5 87 M 36.4 .. sesquioxide of iron Fe20, 85 ...... M 26-8 .. arsenious oxide AsZ03,5 86 ............ 25.3 .. the nitrates RNO, named in 5 88 ...... 23.0 , arseniate of potassium KAsO, 5 88 .. . 25.3 But there is even in a more extended sense approximate equality of atomic heat in bodies of analogous atomic composition. If the formulze of the oxides .RO (oxide of tin for instance) are doubled they become €k,O, and are then analogous to Chose of the sul-phates &SO, ar of tungatate of lime or of perchlorate of OF SOLID BODIES.213 potassium and other salts. To the formulae thus made analogous equal atomic heats corrzspond. The following atomic heats have been found :-Oxide of tin Sn204,compare 9 85 ................ M 27.6 Titanic oxide Ti,04 , ................ M 27.3 The sulphates aSO, in 8 87 .................... M 26.1 Tungstate of calcium CaWO, compare 5 87’ .......... 27.9 Perchlorate of potassium KClO, compare 5 88 ...... 26 3 Permanganate of potassium KMnO, compare 0 88 .... 28.3 If the formulae of the oxides RO, are trebled they become R,06 analogous to those of the nitrates RN,O (nitrate of harium e.g.) and similar salts. Here also approximately equal atomic heats correspond to the formulae thus made analogous.The atomic heats are as follows :-Oxide of tin Sn306 compare 6 85 ................ M 41.4 Titanic oxide Ti,06 ................ M 41.0 The nitrates &N,06 in 5, 88 .................... M 38.1 Metaphosphate of calcium CaP,06 compare 0 88 .... 39.4 How little the atomic heat of compounds depends on their chemi- cal character may be proved from a more extended series of examples than those adduced in the preceding. It is however unnecessary to dwell upon this. The comparisons and considerations contained in the sequel complete what has here been developed as a proof of the principle that the atomic heat of bodies is independent of their chemical character.95. The foregoing comparisons give examples of cases in which bodies of malogous atomic structure with a totally different chemical character have approximately the same atomic heat ; they show that with reference to the atomic heat uni-equivalent and multi-equivalent elementary atoms have the same influence which indeed followed already from Regnault’s comparisons ; that the atomic heat of a substance for its multifold atomic formula may be compared with that of another substance for a simple atomic formula. The preceding contains a generalization of N eumann’s law ;but as certainly as tbis law is recognised in the preceding in a more general manner than wits formerly assumed as little is it universally applicable. Regnault’s investigations have shown that Neumann’s law is EOPP ON THE SPECIFIC HEAT 214 not rigidly valid.Even for those compounds which contain the same element as electronegative constituent and have similar atomic constitution he found the atomic heats as much as to different from each other.* The reason of this he seeks in the same circumstances which in his view prevent a closer agreement 111 the atomic weights of the elements (compare 6 92). Differences 0f this kind and even of greater amount occur in the atomic heats of compounds for which closer agreement in these numbers might be expected-of such compounds that is as contain elements of the same or nearly the same atomic heat combined with the same other element in the same atomic pro- portion. 1’0this belongs the fact that the atomic beat has been found so different (0 85) for the isomorphous compounds magnetic iron ore (37*7),chrome iron ore (31*2),and spinelle (27.7) and for alumina (21.3) and for sesquioxide of iron (26.8).In the atomic heats of such analogous compounds there are differences for which or rather for the magnitude of which as furnished by our present observations I know at present no adequate explana- tion. But there is another kind of difference in the atomic heats of analogous compounds which exhibits a regularity and for which an explanation can be given. Certain elements impress on all their compounds the common characteristic that their atomic Eleat is much smaller than that of most analogous compounds. The atomic heat of boracic anhydride B,O, is only 16.6 while that of most other compounds R,O and g2O3,is between 25 and 28 (5 85).The atomic heat of the borates R B 0, is (5 87) only 16.8 while that of B20, as the mean of the determination in 5 85 is 22*2. The atomic heat of PbB,O is (5 87) only 26.5 while that of Fe,O ($ 85) in the mean is 37.7. Similar results have been obtained for compounds of certain other elements of carbon and of silicum for instance that is of those elements which in the free state have a smaller atomic heat than that of most other elements. This observation leads to the question whether the elements enter into compounds with the atomic heats which they have in the free state and in connexion with this how far isit permissible to make an indirect determination of the atomic heat of the elements (in their solid state) from the atomic heats of their (solid) compounds.* Ann. Ch. Phya [3] i 106. OF SOLID BOUIES. 96. The assumption that elements enter into compounds with the atomic heats they have in the free state would be inadmissib!e if not orily the atomic structure as expressed by the empirical formula but also the grouping of the elements to proximate con-stituents as is endeavoured to be expressed by the rational formula influenced the atomic heat of the compounds. That the latter is not the case is very probable from the comparisons made in 6 94 where approximately equal atomic heats were obtained for com-pounds of analogous empirical formulze even with the greatest dissimilarity of chemical character.That that which may be supposed and expressed by the so-called rational formula in refer- ence to the internal constitution of campounds does not affect the atomic heat becomes more probable from the fact that chemically similar and even isomorphous compounds one of which contains an atomic group in the place of an individual atom in the other exhibit dissimilar atomic heats. This is seen for instance in comparing analogous chlorine and cyanQgen cornpounds (Cy=CN) the latter have far greater atomic heats. Thus the atomic heat Of chloride of mercury HgC1 5 84 is ............ 18.0 .. cyanide of mercury HgCy, 5 89 .............. 25.2 .. chloride of zinc and potassium ZnK,Cl, 84 .... 43.4 ..cyanide of zinc and potmsium ZnK,Cy, 9 89 .... 59.6 In like manner ammonium-compounds (Am =NH,) have atomic heats considerably greater than the corresponding potassium- compounds. This is seen from the following Table :-Chloride of potassium KCl $ 84.. ........ M 12.9 ,J ammonium AmCl 5 84 .......... 20.0 Nitrate of potassium KNO, 9 88 ........ M 28.5 ,,’ ammonium AmNO, $ 88 .. .. . 36.4 Sulphate of potassium KaSO, Q 87.. ...... M 33.6 Y ammonium Am,SO, 5 87 ........ 46.2 97. That undecomposible atoms and atomic groups are contained in compounds with the atomic heats they have in the free state is further probable from the fact that the sum of the atomic heats of such atoms or atomic groups as when united form acertain com- pound is equal or approximatelyequal to the atomic heat of this com- pound.For many compounds whose elements obey Dulong md EOPP ON THE SPECIFIC HEAT Petit's law what has been stated in 9 98 contains the proof that the atomic heat of these compounds is equal to the sum of the atomic heats of the elementary atoms contained in one atom of the compounds. That this is also observed when atomic groups are supposed to be united forming more complicated compuunds will be seen by bringing forward a few examples. The atomic heat has been found- For the oxides go enumerated in § 85 *. .*. . M 11.1 sesquioxide of iron Fe,O, 5 85 .......... M 26.8 _I_ Sum for FeRO . . 37.9 magnetic iron ore Peso4,5 85 ............ M 37-7 the oxides go in 5 85.................. M 11.1 the acids 80 in 85 according to Regnault M 18.8 -Sum for BRO 29.9 chromate of lead PbCrO, 5 87 .............. 29.0 the oxides named in 5 86 RO ............ M 11.1 M '13.8 binoxide of tin SnO, 5 85 - Sum for &RO ...... 24.9 sesquioxide of iron Fe,O, 5 85 .......... 15 26-8 chromate of potassium K,CrO, 0 87 M 36.4 18.8 -Sum for K,CrBO 55.2 acid chromate of potassium K,Cr,O, 5 87. M 53.3 binoxide of tin Sn,06 5 85 .............. M 41.4 base &,O, mean of determinations 5 85 M 22.2 -Sum for R508 ........ 63.6 arseniate of lead Pb,As,O, 8 88 .............. 65-41 To this belongs the faict that water is contained in solid com-pounds with the atomic heat of ice.* The different determina- tions of the specific heat of this substance (5 85) gave the atomic * Even befare Person (oompore Q i4) L.CImelin had speculated (Hand&& der Ohernie [4] Bud. vol. i p. 223) whether from the atomic heat8 of anhydrous sulphata of calcium and of ice that of gypsum could be calculated. The results of calculation deviated considerably from the atomic heat aa deduced from the observed specific heat of gypsum ;the specific heat and therewith the atomic heat of ice were not at that time cornfly known. OF 80LID BODIBS. heat for greater distances from Oo 8.6,and for temperatures nearer Oo 9-1 to 9.2. The atomic heats bave been found- For H30. BaC12.2H,0 5 84.. ................ 41.7 the chlorides 8 CI, 5 84 ........M 18.5 Remains for 2H20.. .... 23.2 11.6 CaCl .6H,O § 84,. ................ 75.6 the chlorides R CI, 0 84 ........ M 18.5 -Bemains for 6H20...... 57.1 9.5 Brucite MgO. H,O 0 85.. .......... 18.1 the oxides go 85 .......... M 11.1 Remains for H,O ...... 7.0 7.0 dioptase CuSiO .H20 86 ....... 28.7 the silicates &SiO, 5 86 ........ &I20.5 Remains for H,O ...... 8-2 8.2 Na2B,0,. 10H,O 5 87 .............. 146.9 Na,B,O, 5 87 .................... 47.1 -Remains for 10 H,O .. 99.8 10*0 gy@um CaSO . 2H20 8 87 .... hf 45.8 the sulphates &SO, 4 87 ...... M 26.1 -Remains for 2H,O .... 19.7 9.9 TheTabIes in $8 84 to 89 contain data for several such compari- sons which lead to the same result as the preceding-that the atomic heat of water contained in solid compounds may by sub-tracting the atomic heat of the anhydrous solid from that of the hydrated solid compound be obtained ill sufficient approximation to the atomic heat deduced from the direct deterrniuation of the specific beat of ice.The deviations from each other and from the atomic heat of ice as directly determined which these indirect determinations exhibit are not to be wondered at when it is considered that all uncertainties in the atomic heats from whoa difference the atomic heat of solid water is deduced are coucen-tmted upon this difference. 98. The view already expressed and defended (compare especi- ally $8 12 and 13) that atoms and atomic groups are contained EOPP ON TEE SPECIFIC HEAT in solid compounds with the same atomic heat that they have in the free state is opposed to the view which has also been fre-quently expressed and defended-that the atomic heat of an element may in certain compounds differ from what it is in the free state and may he different in different compounds.This view and the reasons which may possibly be urged in its favour must here be discussed. The first statement of this view (compare § 6) simply goes to assert that the atomic heats of compounds may be calculated in accordance with the values resulting from the determinations of the specific heat aasumjng that one constituent of the compound has the same atomic heat as in the free state the other an altered one.What alteration is to be assumed depends merely on what assumption adequately satisfies the observed specific heat of the compound. The accuracy of the assumption is susceptible of no further control; the assumption itself cannot be regarded as an explanation of the observed atomic heat of the compound. And nothing is altered in this by assuming (compare $5 6 and 11) that the changes in the atomic heat of a substance on entering into chemical compounds take place in more or less simple ratios. A greater degree of probability must be granted to the view (compare $ 10) that the atomic heats of the constituents of com- paunds and the differences in the atomic heats of these bodies according as they are combined or in the free state depend upon the state of condensation in which these bodies are contained.If for instance from a consideration of the specific gravities or specific volumes (the quotient of the specific weights into the atomic weights) of compounds and of their constituents a con- clusion could be drawn with some degree of certainty as to the state of condensation in which the latter are present in the former and if definite rules could be given for the variations of the atomic heats with the state of condensation the result of such an inves- tigation if it agreed with the observed results for the atomic heats of compounds might be called an explanation of these ob-servations. But what is here presupposed is partially not attailled and partially not attempted. And moreover as far as can he judged from individual cases the same element when present in different states of condensation appears to have the same atomic heat.It has been attempted to deduce the state of con-densation or the specific volume of oxygen in its compounds with heavy metals by subtracting from the specific voluae of the oxide OF SOLID BODIES. 219 that of the metal in it and considering the remainder as the volume of oxygen. It would follow from this that the specific volume of oxygerr in cuprous oxide is much greater (about four times as great) than in stannic oxide. But if the atomic heat of oxygen be deduced by subtracting from the atomic heat of the oxide that of the metal in it it is found that the atomic heat of oxygen in cuprous oxide and in stannic oxide gives almost exactly the same number.Hence it does not seem that the state of conden-sation in which a constituent may be contained in a compouiid has any material influence on the atomic heat of this con-sti tuen t. 99. From all that has been said in the foregoing paragraphs the following must be adhered to. (1) Each element in the solid state and at a sufficient distance from its melting point has one specific or atomic heat which may indeed vary to a certain extent with physical conditions different temperature or density for instance but not so considerably as to be regarded in consi- dering in what relations the specific heat stands to the atomic weight or composition; and (2) that each element has essentially the same specific or atomic heat in compounds as it has in the free state.On the basis of these two fundamental laws we may now investigate what atomic heats individual elements have in the solid free state and in compmnds. According to these proposi- tions indirect deductions of tne atomic heats of such elements as could not be investigated in the solid free state are admissible in this sense; that from the atomic heat of a compound containing such an element the atomic heat of everything else in the com- pound is subtracted and the remainder considered as the expres- sion for the atomic beat of that element. Such indirect deter- minations of the atomic heat of elements may be uncertain partly because the atomic heat of the compounds is frequently not known with certainty as is seen from the circumstance that analogous compoiinds for which there is every reason to expect the same atomic heat are found by experiment to have atomic heats not at all agreeing; but more especially because the enatire relative uncertainty in the atomic heats for a compound alld for that which is to be subtracted from its composition is concen-trated upon a small number the residue remaining in the deduc- tion.But when such deductions are made not merely for indi-vidual cases but for different compounds and for entire series of corresponding compounds they may be considered sufficiently KOPP ON TH3E SPECIFIC HEAT trustworthy to make the speculations based upon them worthy of attention. Of course in indirectly deducing the atomic heat of an element it8 simpler compounds and those containing it in greatest quantity (measured by the number of atoms) promise the most trustworthy results.100. For silver aluminium arsenic gold bismuth bromine cad-mium cobalt copper iron mercury iodine iridium potassium lithium magnesium manganese molybdenum sodium nickel os-mium lead palladium platinum rhodium antimony selenium tin tellurium thalhm tungsten and zinc it may be assumed from the determinations of their specific heat in the solid state (5 821 that their atomic heats in accordance with Dulong and Petit's law are approximately equal the average being 6.4. 1 do not believe that all these elements have really the same atomic heat but think that some of them will hereafter be considered as exceptions to the above-mentioned law as it will in the sequel be proved that several other elements have an atomic heat differing from 6.4.But for none of the previously mentioned elements are the present data and the presumed deviation of the atomic heat from that of other elements sufficient to justify their separation from them. With the elements just mentioned chlorine must be associated from the close agreement of the corresponding chlorine bromine and iodine compounds (5 84) and of the compounds KClO, 24.8 and KAsO, 25-3 (5 88). To the atomic heats of these latter compounds those of individual salts KNO, approximate clovelp; the latter gave (5 88) 21*8-24*4, mean 23.0,which on the whole agrees nearly enough with those found for the metallic oxides B,O (5 85).I count nitrogen also among the elements whose atomic heat may be assumed at 6.4,like that of most other elements without however considering the determi- nation of the atcmic heat of this element as very trustworthy. To deduce the atomic heat of this element with certainty com- pounds are wanting which contain besides nitrogen elements whose atomic heat has been directly determined. The fact that the atomic heat of the nitrates Z2N2O6,was found (5 88) in the mean to be 38.1 a third of which 12.7 is somewhat less than the average atomic heat found for the oxides of heavy mctals of the formula go, might be a reason for assigning to nitrogen a smaller atomic heat; while on the other hand the atomic heats Gf other citrogen-compounds in which it is true other elements OF SOLID BODIES.enter whose atomic heat is only indirectly determined do not favour this view. Iu the class of elements with the atomic heat about 6.4 barium calcium,and strontium may be placed from the agreement in the atomic heats of their compounds with the atomic heats of corre-spondiug compounds of such elements as have been found by the direct determination of their specific heat in the free solid state to belong to that class (compare the atomic heats of the com-pounds gC1 in 5 84 WO in 4 86 &SO in 5 87 and &N,O6 in 5 88) ; further rubidium (compare the atomic heats of the com- pounds RC1 in 5 84 and R,CO in 6 86); then also chromium (from the agreement in the atomic heats of Cr,O and %e203, 5 84) and tltunium (from the agreement in the atomic heats of TiO and SrO, 4 84).To place zirconium in the same class has no other j uvtification than that 011 this assumption the atomic heat of zircon may be calculated iu accordance with that deduced from the observed specific heat of this mineral. 101. According to direct determinations of the specific heat sulphur and phosphorus do not belong to this class. The more trustworthy determinations (for the sulphur the last two for phos-phorus the last three of the numbers in 0 82) assign to these elements the atomic heat 5.4. That sulphur has a smaller atomic heat than the elements discussed in the last paragraphs follows from the atomic heats of sulphur-compounds compared with those of the corresponding compounds of such elements as have an atomic heat = 6.4.The average atomic heat of compounds RS and €&S is 11.9 according to the determinations iu 5 83 while those of chlorine-compounds RC1 and &Cl ($84) = 12-8,that; of the corresponding bromine-compounds = 13.9 and of the corresponding iodine-compounds = 13.4. In comparing more complicated sulphur-compounds snlphates for instance with other compounds of analogous composition the same is met with although such complicated compounds are of little value in giving data for deciding on such small dift'erenceu. The specific heat of the simpler phosphorus-compounds has not been investigated ; for more complicated compouiids although they point to a smaller atomic heat for P than 64 the above remark also applies.The determinations of the specific heat of siliciurn give for this element also a smaller atomic heat than 6.4 (compare 5 82),and the same conclusion results from a comparison of the atomic heats of SiO, arid the oxides go, of the silicates &SiO and VOL. XIX. R KOPP ON TEE SPECIFIC HEAT the oxides &,(I3. The atomic heat to be assigned to silicium cannot as yet be settled with any degree of certainty. Direct determinations varying considerably from each other g'we a specific heat mostly greater than 4; while the numbers obtained indirectly and themselves also not closely agreeing are partly considerably smaller. If in the sequel I put the atomic heat of silicium at 3.8,corresponding to the lowest number found for the specific heat of this element I do so for want of other and more certain data.I consider this number as quite uncertain. The atomic heat of boron from the direct determinations of the specific heat is considerably smaller than 6.4; and the atomic heats of boron-compounds confirm this conclusion as was dis-cusssd in 5 5 93 and 95. By comparing the atomic heats of such boron and sulphur-compounds as contain along with boron and sulphur the same elements in the 6ame proportions the atomic heat of boron is found to be half that of sulphnr. The atomic heat of KBO = 16.8 is exactly half that found for K,SO = 33.6; the atomic heat of PbB,O = 26.5 is almost exactly equal to that for PbSO = 26.7.Taking the atomic heat of S in ac- cordance with the above discussion at 5.4 that ofB would be 2-7;the numbers obtained directly for the atomic heat of boron (5 82) from the experiments on the specific heat of this element agree with sufficient accuracy. In the sequel I take the atomic heat of boron at 2.7. A smaller number is obtained in other com- prisons; for instance of the atomic heats of B,O and of the oxides a,O, or of the salts RBO and the oxides S,O ; but in such indirect determinations of the atomic heat where such small numbers are to be determined as is here the case with the atDmic heat of boron the results are very uncertain owing to the fact that the entire uncertainty iri the atomic 'heats of the corn- pounds and in the assumption that the elements corresponding to boron in compounds of analogous composition have really the atomic heat = 64 is thrown on the final result.Lastly carbon also from the direct dcterrninations of its specific heat (8 82) has a much smaller atomic heat than 6.4. The same result follows from a comparison of the atomic heats of carbon-compounds the atomic heat of the carbonates &,co = 28*4asthe mean of the determinations in 5 86 is much smaller than that of a,03(= 3atO) which is the mean of the numbers in 9 85 = 33.3; the atomic heat of the carbonates &CO = 20.7 as the mean of the determinations in $ 86 is much smaller than OF SOLID BODIES. 2s7.1 the number found for Asf03 Bi203 Cr203 Fe203,and Sb,O as the atomic heat of oxides I put the atomic heat of carbon at 1.8 for C as deduced from the determination of the specific heat of its purest variety diamond.102. In the preceding paragraphs I have discussed the ele- ments which from the determinations of their specific heat in the solid free state have a smaller atomic heat than about 6.4. There remain to be discussed a few elements whose atomic heats are also less than those of most other elements but can only be deduced from those of their compounds. To this category belong hydrogen* even if the indirect deter- mination of its atomic heat in the solid state is liable to the un- certainty just discussed. The atomic heat of water H,O is ($85) = 8.6 and smaller by 7 than that of suboside of copper C1i2O which was found in the mean to be 15.6; the atomic heat of hydrogen would thus be % = 3.5 less than that of the elements to which copper belongs as regards its atomic heat ; hence the former would be 6.4 -3.5 = 2.9.The atomic heat of chloride of ammonium NH,Cl has been found to be 20-0(9 84) ; the subtraction of the atomic heats for N + Cl = 6.4 + 6.4 = 12.8 leaves 7.2 as the atomic heat of 4H and therefore 1.7 for that of H. The atomic heat of nitrate of ammonia N,H,O, is 36.4 (5 88) ; suhtracting therefrom as the atomic heat of N + 0,,the num- bcr 27.1 which has previously been frequently mentioned as the atomic heat of oxides Z&,O, we have 9.3 as the atomic heat of 4H that is 2.3 for that of H. I put in the sequel the atomic heat of hydrogen at 2.3.That oxygen has a smaller atomic heat than 6.4 follows from the fact that the oxygen compounds of the metals have a con-siderably smaller atomic heat than the corresponding chlorides iodides or bromides. For instance the atomic heat of the oxides a0 is as the mean of the determinations in 3 85 = 11.2 while that of the chlorides RC1 and aC1 (5 84) is 12.8 that of the corresponding bromides 139 and of the corresponding iodides 13.4. That of the oxides go, as the mean of the determina- tions in 5 85 of &h02, SnO, and TiO is 13.7 while that of * L. Gmelin (Handbuch der Chemie 4 Aufl vol. i pp. 216 and 222) ascribed ta hydrogen the same capacity for heat as that of an equivalent quantity of lead or mercury (H = 1 Cu = 31.7 Hg = 100); Schroder (Pogg.Ann. vol. Ivii. p. 279) and Cannizzaro 1,11Nuovo Cimento vol. vii. p. 342) ascribed to hydrogen the same atomic heat as that of most other elements (I€ = 1 C1 = 35.5 Cu = 63.4 Hg = 200). R2 KOPP ON THE SPECIFIC HEAT the chlorides aCl (5 85) is 18.5 and of the iodides BT = 19.4. Taking the atomic heat of the other elements which are contained in the following compounds at 6.4. the atomic heat of oxygen as deduced from the atomic heat of the oxides a0 (11.1 in the mean) is = 4.7; as deduced from the oxides g203(27.1 as the mean of the oxides of this formula previously frequently men- tioned) it is = 4.8;from the above oxides go (13.7 in the mean) it is = 3.7; it is found (compare 8 88) from HASO (25.3)to be 4.1 ; from Pb,As,O (65.4) to be 4.2 ; from HC10 (24.8) to be 4.0; from KC10 (26.3)to be 3.4; from KMnO (28.3) to be 3.9.In the sequel the round number 4 is taken for the atomic heat of 0. Fluorine appears lastly to have an atomic heat considerablj smaller than 6.4. The atomic heat of fluoride of calcium CaFl, has been found to be (5 84) only 16.4 considerably smaller than the corresponding chlorides bromides and iodides. I put th6 atomic heat of fluorine at 16.4-6.4-5. 2 103. Taking in accordance with what has just been said the atomic lieat which an element has in a solid compound At 6.4 for Ag Al As Au Ba Bi Br Ca Cd C1 Co,Cr Cu Fe Hg I Ir K Li Ma Mn Mo N Na Ni Os Pb Pd Pt Rb Rh Sb Se Sn Sr Te Ti T1 W Zn and Zr At 5.4 for S and P at 5 for F1 4 for 0 3.8 for Si 2.7 for B 2.3 for H,and 1.8 for C ; and assuming that the atomic heat of a solid is given by the sum of the atomic heatsjof the elements in it we obtain the atomic heats; and dividing them by the atomic weights we obtain the specific heats in sufficiently close agree- ment with the specific heats as obtained by direct determinations of this property.In the following Table I give for all compounds for which the specific heat has been determined in a trustworthy manner the specific heat calculated on these assumptions compared with the numbers found experimentally. This calculation arid this compari- son are givenin the same order which was followed in the synopsis 9 82 to 89 and I refer to the latter aa regards special remarks on the determinations.To distinguish the observers N. again stands for Neumann R. Regnault Kp. Koyp Pr. Person A. Alluard and Pp. Pape. 225 OF SOLID BODIES. AZZoys. (Compare 9 82.) BiSn ......328 12.8 0-0390 O-OM R. BiSnt ...... 446 19.2 00430 0-0450 R. Bi Sn2Sb .... 668 25-6 0.0451 00462 R. Bi Sn Sb Zns .... 698.4 38.4 0.0550 0.0566 R. PbSb ...... 329 12.8 0.0389 0.0388 R. PbSn .. . .. 325 12.8 0-0394 004to7 R. Pb Sns .. ....443 19.2 0.0433 0.0451 R. 104. Arsenides and Sulphides. (Compare 6 83.) CoAb .. .... 208.8 19.2 0.0919 0-0920 N. Agt S .. .... 248 18.2 0.0'734 0074.6 R. co A8 s.. .... 166 18.2 0110 0.107 N. cups .. .... 158.8 18.2 0.115 0121 R. 0.120 Xp. FeAsS.. .... 163 18.2 0112 0.101 N. ASS .. .... 107 11.8 0.110 0.111 N.co s .... 90.8 11.8 0.130 0.125 R-. Cut FeiS .... 91.7 11% 0.129 0.129 N. 0131 Kp. FeS .. .... 88 11-8 0.134 0-136 B. .... 232 11.8 0.0509 0.052 N. 0.0512 R. 0051'7 Kp. ::ss : .... 90.8 11.8 0130 0.128 R. PbS .. ....239 11-8 0.04999 0.053 N. 0.0509 B. 0.0490 Ep. SnS .. .... 150 11.8 0.0783 0.0837 R. ZnS .* .... 97-2 11.8 0.121 0.115 N. 0.123 R. 0.120 Ep. FqSS .. ....648 88.0 0136 0153 N. 0.160 R. As,S .. .... 246 29.0 0.118 0113 N. Bi2S3 .. ....516 29.0 0OF62 0.060 R. Sb283 .. .... 34.0 29.0 0-0853 0090'7 N. 0.0841) R. Be& .. .... 120 17.2 0.143 0*128-0*133 N.0.130 R. 0.126 Kp. MOS~.. ....160 17.2 0-107 0107 N. 0123 €6. SnSs .. ....182 17.2 0.0945 0.119 R. 105. Chlhdes Bromides Iodides and Fluorides. (Compare $84.) Ag 01 ......143'5 12.8 0.0892 0.0911 R. Cu 01 ...... 98'9 128 0129 0138 R. Hg C1 ......235% 12-8 0.0543 0.0521 R. K 01 ...... 74.6 18.8 0.172 0.173 R. 0171 Kp. Li Cl ...... 426 12.8 0.301 0282 R. NaC1 ...... 58.5 12.8 0219 0214 R. 0'213-0'219Xp. Rb Cl .... 1209 128 0106 0.112 Kp. N H oi' .... 53.6 22.0 0.411 0.373 KP. Ba C11 ...... 208 19.2 0.0923 0.0896 R. 0.0902 Kp. Ca C12 ...... 111 192 0.173 0164 R. Hg Cls ......$71 192 0.07CB 0.0689 R. 0.640 KP. Mg Clz ...... 95 192 0,202 0.195 R. 0.191 KP. MUClz ...... 126 19.2 0.152 0143 R. Pb C12 ...... 278 19.2 0.0691 00664 R. Sn CIS ......189 19.2 0102 0102 R. Sr Clz ...... 158-6 19.2 0121 0.120 R. zn Clz .. ..1362 19-2 0141 0136 R. Be C14.2H~0: ..244 364 0*1@ 0.1'71 Kp. .... "Fp ,PI ::: ::: ....o::w:s:::::: N N Q n &O 0 .................. .................................... .................. oo o o o o o o o o o o o o o ooo Snecific z cn Q w 'p 978.0 fIT€.O 0.88 8LZ -* OZBL'~0S 9d 8W.O 811.0 0.88 8.082 '* 0'H 4 "0 8 03 818.0 zos*o 'P.64 8.292 '* O'H9''OS FN 8ZE.0 yP62.0 8-04 192 ** 0'H 13 "0 SUE 582-0 V8Z-0 8.04 8.6W '* 0 'H 9 "0 8 "3 L'pZ.0 09z.o 9.&9 902 *' OZHC"OS ad 'pzz.0 822.0 O*9P 2.461 '* 0'H Z * '0S *. 0'H Z * '0 S n3 Z1Z-0 OEZ.0 0.99 t.961 *' r4z.o 292.0 0.9P 2L1 O'H 2 "0 S "3 zoz*o EOZ.0 V.98 2.641 ** OzH ''0Su2 WZ.0 F9Z.O 9-96 811 ** OzH ''OS%X ZOZ.0 902.0 9-98 7.441 ** OzH "OSnD .. .. 'pL1.0 Z41-0 8.42 2.191 .. .. "'0 s u2 8'PT.O 191.0 8.4Z 9.181 .."'0 SJlt ZL80.0 LT6O.O 8.42 60C *. '0 s qd 281-0 V81-0 8.42 191 .. .. .. .. '0 s *W zzz.0 2EZ.O 8.42 oz1 .. '0s .I V81-0 V4T.O 8-4Z 't.691 '.*O s "3 0. .. 881-0 '8 461.0 fOZ.0 8.4Z 911 .. .. "'0 s "3 811.0 'N 601.0 611.0 8.4Z €12 "'0 s "8 ** '0s8~bN .dE 096.0 86E.0 9.ZQ 211 ** 4ZZ.O '8 112.0 1VZ.O Z*V€ 271 .. .. '0S QN 961.0 Tl 061.0 961.0 Z-TI Z.9LT. .. .. .. "'0 SzE 'dX 9FZ-0 TZZ.0 T.08 1.981 .. 'ORHE 681.0 281.0 9-89 9.P6Z .. .. LO'J3'E 981.0 *'I€ 681-0 -8 981.0 181.0 Z.9€ 9.961 .. .... '0 J3'E 'dE 0060.0 1680.0 8-82 Z*EZ€ .. '0 J;3 96 *' 0860.0 '8 8460.0 6960.0 8-82 7.808 .. ..f'O&8UN&3d 'dE 4960.0 OOT.0 8-82 882 '0 M "0 'dX tZ80.0 9840-0 8.82 L9€ *' .* PooJqqd 'dX 981.0 998.0 9-4€19.188 ** OZHO1"O%~N ** LOP8 ZqN 6ZZ-0 '8 812.0 992.0 9-19 9.102 ..'23 ozz-0 1ZZ.O 9.1s 8.113 .. .. '0'8'E 'X 911.0 7ZT.O z.s'p 9.291 .. .. '0 '84d .. .. 'X 9060.0 6ip60.0 8.42 8.262 .. .. '0 93 96 '8 49z*o 09Z.O 1-41 6.99 '0 8 "N *8 9OZ.O 60Z.O 1.41 28 .. .. *"o 8a 'dX 061.0 'N 961.0 912.0 'P.2118.9Z9 'dE €81.0 'N 161.0 202.0 7.z11 L99 'dE 681-0 'N 902.0 Izz.0 9.28 8*9'P1 'dX 281.0 961.0 8-01 T.491 'dE 981.0 'N 161.0 9oz.o 2-zz 801 +I841-0 161.0 z.2z 911 '8 971.0 'N 991.0 4s1.0 2.02 9.491 *dE 1640.0 'N 'F180.0 4940.0 z.oz 49z 'N 422.0 222.0 2-OZ 1-16 'dE 991.0 641.0 2.02 6.Z11 91z.o ozz.0 2-02 26 *dE 902.0 '8 81Z.0 'N 9OZ.O '8 60Z.O 'N €02.0 zoz-0 2.02 001 '8 011.0 " 801.0 €01.0 Z*OZ 461 'dE 821.0 *SPI~OBanos 60 tZZ 228 KOPP ON THE SPECIFIC HEAT Mg S 04.7 H2 0 *.246 88.0" 0.35; 0.362 Kp. 0407 Pp. Ni S 04.7 H2 0 .. 280.8 88.0 0.313 0.341 ZnS04.7H20 .. 287.2 880 0.306 0.347 g:. 0.328 Pp. Mg K2 S2 08.6 H2 0.. 402.2 113.6 0,282 0.264 Xp. NiK2S208.6H20.. 437 113.6 0.260 0.245 Kp. Zn K2 S2 08.6 H2 0 . . 443.4 113.6 0.256 0.270 Kp. A12 K2 54 016.54 H2 0. 949 317.6 0.335 0.371 Kp. Cr2 K2 S4 Ole. 24 H2 0. 998.6 317.6 3.318 0.324 Kp. 109. Arseniates Phosphates Fyrophosphates and Metaphosphates Nitrates Chlorates Perchlorates and Permanganates. (Compare 6 88.) I(As O3 .. .. 162.1 24.8 0.153 0-156 R. K H2 As O4 .. .. 180.1 33.4 0,185 0175 Kp. Pb3 As2 08 .. .. 899 64.0 0.0712 0.0728 R. ~H~po404 .. .. 419 40.6 0,0969 0*0896?Kp. .. 136.1 32.4 0.238 0.208 Kp. Na2 H P 04.1i*H20..358 139.7 0.390 0.408 Pr. ~ Pbs P 08 .. ,.. 811 62-0 0.0764 0-0798 R. K4P207 .. ,. 330.4 64.4 0.195 0.191 R. I Na4P207 .. .. 266 64.4 0.242 0.228 R. PbzP2 07 .. .. 688 61.6 0.0878 0.0821 R. Na-P 0 .. 102 23.8 0.233 0.217 KP. I. CaP2 06 .. .. 198 41.2 0.208 0.199 R. AgN 03 .. . 170 248 0146 0-144 R. EN03.. .. .. 101.1 24.8 0.245 0.239 R. 0.230 Kp. E+Na+N03 .. 93 24.8 0267 0.235 Pr. I. NaN03 .. .. 85 24-8 0.292 0278 R. 0.25'7 Ep. N2H403 ma ,. 80 340 0.425 0-455 BaN206 .. .. 261 43-2 0.166 0.152 Ep' 0.145 Kp. PbN206 .. .. 331 43.2 0.130 0.110 KP* Sr N2 06 .. 211.6 43.2 0.204 0.181 KD. E C1 03.. .. 122.6 24.8 0-202 0.210 Ba C12 06. Hz 0 .. 322 51-8 0.161 0.15'Z E C1 04.. .. .. 1386 28.8 0,208 0.190 E Mn 04 .... 158.1 28.8 0-182 0179 110. Organic Compounds. (Compare tj 89.) Cyanide ofmercury Hg C2N2.. .. .. 252 22.8 0091 0100 Kp. p;;assiu$c }Zn K2C4N4 @ * .. 247.4 52.0 0.210 0.241 Kp. Ferrocyanide of po-Fe I(3 c6N6 .. .. 3293 '74.8 0'227 0.233 Kp. tassium .. .. I FerricSaniile Of Po-Fe4 K4 C6 N6.3 H20 * 422.4 107.0 0.253 0-280 Kp. t)assium.. .. I Chloride of carbon. C2C16 .. . .. 237 42.0 0.177 0.178 Kp. ,@ Naphthalene Clo H8 .. .. .. 128 36.4 0.284 0810 A. OF SOLID BODIES. Cerotic acid 108.8 0.44J Palmitate .. of C46 Hg2 02 .. 676 302.4 0.447) 0*429 Pr' syle .I Cane-sugar .. Cl2 HB 011 .. 342 116.2 0.3pO 0301 Kp. a. Mannite .. .. c6 Hi4 06 182 67.0 0.368 0.324 Kp. a. Succinic acid c4 H602.. .. 118 37.0 0.314 0'313 Kp.Tartaric acid c4 H606.. a. 150 45.0 0.300 0.288 Kp. Racemic acid .. C2 H6 Os.HzO.. 168 53.6 0319 0.319 Kp. Formiate of barium.. C2 H Ba 04 .. 227 30.6 0.135 3.143 Kp. Oxalate of potassium. C2I( O4 . Hz 0.. 1842 41-0 0.223 0.236 Kp. Quadroxalate of pot-254.1 69.7 0.2'74 0283 Kp. ass .. .. Bitart,rate of potassium C4 H K O6 .. 188.1 49.1 0.261 0.257 Kp. Seignette salt .. C4 H4 Na K 06 .4 H2 0282.1 87.6 0.311 0.328 Kp. Bimalate of potassium Cs Hlo Ca O1,. 8 Hz 0 450 152.6 0.339 0.338 Kp. 111. The preceding synopsis shows for the great majority of substances contained in it an adequate agreement between the observed specific heats and those calculated on such simple assump- tions. In estimating the differences the extent must be remem- bered to which various observers differ for the same substance.It must be considered that the present better determiuations of the specific heat even those made by the same experimenter for sub- stances where it may be expected that Neumann's law applies do not agree exactly with it not more nearly than within & or Q of the value; and that for those elements which are considered here as obeying Dulong and Petit's law even greater deviations occur between the numbers found experimentally and those to be expected on the assumption of the universal validity of this law. (These deviations i.e. the differences between the atomic heats found for these elements are seen from 582.) The extent to which the experimentally determined specific heats deviate fiom such a law Neumann's for instance in bodies for which calcu- lation takes it as applying gives of course the means of judging what differences may occur between the observed and calculated numbers without invalidating the admissibility of the calculation attempted.And it is as much a matter of course that in those bodies in which a marked deviation from Neumann's law has heen already mentioned (compare 595) a greater difference is found in the present synopsis between calculation and observa- tion. I consider the agreement between calculation and observation HOPP ON THE SPECIFIC HEAT as shown in the synopsis 5 103 to 110 as in general sufficient for a first attempt of that kind. But it need scarcely be mentioned that I by no means consider the calculated as more accurate than the observed numbers or among several numbers consider that the most accurate which is nearest the calculated ; for that the bases of cdculation are much too uncertain.The list of atomic heats given at the commencement of 5 103 is scarcely much more accurate than were the first tables of atomic weights; but just as the latter have experienced continual improvements and thus what was at first only an approximate agreement between the calculated and observed composition of bodies has been brought within considerably narrower limits and apparent exceptions have been explained so in like manner will this be the case for ascertkining what atomic heats are to be assigned to the elements and how the atomic heats of compounds may be deduced therefrom.This much however may even now be said that while formerly for many solid substances a statement of the specific heat could in no way be controlled a concealed source of error for the determina- tion of this property was not indicated and an error which mate- rially altered the number for this property could not be recognised at present even if only roughly such a control is possible. Com-pare 5 77. PARTVI.-Considerations on the Nature of the Chemical Ekrnents. 112. The proof given in the preceding that Dulong and Petit’s law is not universally valid justifies certain conclusions in re-ference to the nature of the so-called chemical elements which may here be developed. What bodies are to be regarded as chemical elements 3 Does the mere fact of nondecomposibility determine this ? or may a body be nondecomposible in point of fact and yet from reasons of analogy be regarded not as an element but as a compound 3 Thehistory of chemistry furnishes numerous examples of cases in which sometimes one and sometimes another mode of view led to results which at present are regarded as accurate.The earths were in 1789non-decomposible in point of fact when Lavoi sier expressed the opinion that they were compounds oxides of unknown metals. Lavoisier’s argumentation was based on the fact that the earths enter as banes into salte and that it wae to be assumed in regard OF SOLID BODIES. to all salts that they contained an oxygerr-wid and an oxygen-base.But the view founded on the same basis that common salt contains oxygen and the subsequent view that what is now called chlorine contained a further quantity of oxygen besides the elements of an oxygen-acid did not find an equally permanent recognition. On the basis of the actual nondecomposibility of chlorine Davy from about 1810 niaintained its elementary . character; and this view has become general especially since Berzelius after a long struggle against it adopted it more I think because he was out-voted than because he was convinced. Almost all chemists of the present time consider chlorine and in conformity therewith bromine and iodine as elemei tary bodies ; but we know with what persistence Scbonbein attacks this view and adheres to the opinion that these bodies are oxygen- compounds peroxides of unknown elements.Is there anything which enables us to decide with greater certainty on the elemen- tarynature of chlorine and the analogous bodies than has hitherto been the case ? No one can maintain that the bodies which chemists regard as elemerits are absolutely simple substances. We are cornpelled to admit the possibility that they may be decomposed into still simpler bodies; how far a body is to be regarded as an element is so far relative that it depends on the development of the means of de-composition which practical chemistry has at its disposal and on the trustworthiness of the conclusions which theoretical chemistry can deduce. A discussion as to whether chlorine or iodine is an elementary body can be taken only in the sense whether chlorine is as simple a body as oxygen or manganese or nitrogen; or whether it is a compound body as peroxide of maAgauese or peroxide of hydrogen for example.If Dulong and Petit’s law were universally valid it would indicate not merely for chemical elements a relation between the atomic weight and the specific heat in the solid state but it could be used as a test for the elementary nature of a body whose atomic weight is known. That iodine from a direct determination and chlorine by an indirect determination of specific heat had atomic heats agreeing with Dulong and Petit’s law would be a proof that iodine and chlorine if compounds at all are not more so than other so-called elements for which this law is regarded as valid.According to Ne urnann’s law compotlnds of m-taloguus atomic KOPP ON TEE SPBCIFIC HEAT composition have approximately the same atomic heats. In general bodies whose atom consists of a relatively greater number of non-decomposible atoms or is of more complicated composition have greater atomic heats. In these compounds more especially those whose elements all follow Dulong and Petit's law magnitude of atomic heat is exactly a measure of the complexity or of the degree of composition (compare 93). If Dulong and Petit's law were valid it could be concluded with great positiveness that the so-called elements if they are compounds of unknown and simpler substances are compounds of the same order.It would be a remarkable result that the act of chemical decomposition had everywhere found its limit at such bodies as those which if compound at all have with every difference of chemical deport- ment the same degree of complexity. Imagine the simplest bodies probably as yet iinknown to us the true chemical elements forming a horizontal spreading layer and piled above them the simpler and then the more complicated compounds ;the universal validity of Dulong and Petit's law would include the proof that all elements at present assumed by chemists lay in the same layer and that chemistry in recognising hydrogen oxygen sul- phur chlorine and the different metals as nondecomposible bodies had penetrated to the same depth in that field of inquiry and had found at the same depth the limit to its penetration.This result I formerly propounded* when I still believed in the validity of Dulong and Petit's law. But with the proof that this law is not universally true the conclusion to which this result leads loses its justification. Starting now from the elements re- cognised in chemistry we must rather admit that the magnitude of the atomic heat of a body depends not only on the number of elementary atoms contained in one atom of it or on the com-plexity of the composition but also on the atomic heat of the elementary atoms entering into its composition; it appears now possible that a decomposible body may have the same atomic heat as a non-decomposible one. To assume in chlorine the presence of oxygen and to consider it as analogous to peroxide of manganese or in general to the peroxide of a bi-equivalent elementt is lass in accordance with * $c Ueber die Versehiedenheit der Materie vom Standpunkt des Empirismos," eine acrtdemische Rede.Qiessen 1860 ;s. 16. t I must not omit to mention that equivalent weights of iodine and peroxide of manganese have almost equal capacity for heat. As regards oxidieing action 127 at OF SOLID 3ODIE8. what is at present considered true in chemistry than to consider it as the peroxide of a monoequivalent element analogous to peroxide of hydrogen. It is remarkable that peroxide of hydro-gen in the solid state or in solid compounds must have almost as great an atomic heat (for HO 2-3+ 4 = 6.3) as those elements which obey Dulong and Petit’s law and especially as iodine bromine aDd chlorine according to the direct and to the indirect determination of theu atomic heat the same must be the case for the analogous peroxides of siich still unknown elements aa have an atomic heat as great as that of hydrogen.As far as may be judged from its specific heat chlorine may be such a peroxide ; but this consideration shows no necessity for assumirig that it actually is so. In a great number of cases the atomic heat of compounds gives more or less accurately a measure for the degree of corn-plexity of their composition.* And this is the case also with such compounds as are comparable in their chemical deportment with undecomposed bodies. If cyanogen or ammonium had not been decomposed or could not be so with the means at present offered by chemistry the greater atomic heats of their compounds com- pared with those of analogous chlorine or potassiurn-compounds (compare $ 96) and of cyauogen and ammonium as compared with chlorine and potassium would indicate the more complex nature of those so-called compound radicals.The conclusion appears admissible that for the so-called elements the directly or indirectly ascertained atomic heats are a measure for the coin- plexity of their composition. Carbon and hydrogen for example if not themselves simple bodies are more so than silicium or oxygen; arid still more complex compounds are the elements which are now considered ap following Dulong mid Petit’s law; with the restriction however that for these also the atomic heats may be more accurately determined and differeaces proved in them iodine corresponds to 43.5 peroxide of manganese; Regnault found the specific heat of the former = 0.0541 ;I found that of the latter = 159 ; 127 x 0.0541 = 6.87; 43.5 x 0-159 = 6.92.* The differences in the atomic heats of the elements are of course most distinctly seen in their free state but in their analogous cornpounds theoe differences are the less prominent the more complex the compounds that is the greater the number of atoms of the same kind and the same atomic heat which are united to those elementary atoms whose atomic heat is assumed to be unequal. The difference in the atomic heate of C and As for instance (1.8 and 6*4) is relatively far greater than for CaC03 and KhO1(20.2 and 248).234 KOPP ON THE SPECIFIC HEAT OF S\^)LID BODIES. which justify similar conclusions.* One might be tempted by comparing atomic heats to form an idea how tbe more complex of the present non-decomposible bodies might be composed of more simple ones just as such a comparison has been shown to be possible for chlorine; but it is at once seen that to carry out such an attempt the atomic heats of the elements especially those which can only be indirectly determined are not settled with adequate certainty. It may appear surprising or even improbable that so-called elements which can replace each other in compounds as for instance hydrogen and the metals or which entm into compounds as isomorphous constituents like silicium and tin should possess unequal atomic heats and unequal complexity of composition.But this is not more surprising than that undecomposible bodies and those which can be proved to be compound as for example hydrogen and nitric peroxide or potassium and ammonium should replace one another preserving the chemical character of the compounds and even be coritaiiied as corresponding constituents in isomorphoris compounds. I have here expressed suppositions with reference to the nature of the so-called elements which appear to me based on trustworthy conclusions from well-proved principles. It is in the nature of the case that the certain basis of fact and of what can be empi- rically demonstrated must be left.It must also not be forgotten that these conclusiorrs only allow something to be supposed as to which of the present non-decomposible bodies are inore complex and which of simpler’composition and nothing as to the question what simpler substances may be contained in the more complex ones. The consideration of the atomic heats may indicate some- thing as to the structure of a compound atom but in general gives no clue as to the qualitative nature of the sinipler substances used in the construction of the more complex atoms. But even if these suppositions are not free from uncertainty and imperfection they appear worthy of attention in n subject which for scimce is still so much in darkness as is the nature of the non-decomposible bodies.* It is possible for example that certain non-decomposible bodies which only approximately obey Dulong and Petit’s law are analogous compounds of simpler snbstances of essentially different atomic heat the approximate agreement of the atomic heats of such non-decomposible bodies would then depend on a reason similar to that which has been given for the atomic heats of CaC03 and KAs03. (Compare the previous note.)

ISSN:0368-1769    

DOI:10.1039/JS8661900154

出版商:RSC    

年代:1866

数据来源: RSC