摘要:

CHEMICAL SOCIETY OF LONDON. IIoiise of the Society of Arts John Street Adelphi. 23rd February 1847. A MEETING was convened to take into coasideraticn the formation of a Chemical Society at which meeting a Provisional Committee was appointed for carrying that object into tXiJct. The Provisional Comniittee having issued a printed circular in- viting a number of gentlemen engaged in the practice and pursuit of Chemistry to become original members the following gentlemen communicated their written assent :-Aikin Arthur. Andrews Dr. Thos. Barron Rev. J. A. Blake Jas. Blythe Win. Brande Prof. W. T. Brayleg E. W. Jun# Brooke €1. J. Button Chas. Clark Dr. Thos. Cock W. J. Cooper J. T. Cooper J. T. Juu. Crossc A 11dre \v. Crurn Walter.Cumming Prof. J. Danieil Prof. J. F. Daubeny Dr. C. Davy Dr. E. De la Rue IF7. Everitt Thos. Ferguson Wm. Fownes G. Frampton Dr. A. Gassiot J. P. Gill Thos. C'hein. Proc.-?rJo. Graham Prof. Thos Graham John. Griffin J. J. Grifitlis Thos. Grove IV. R. Heisch C. Hennell 1%. Henry T. €1. Herapath Wni. Hope Dr. T. C. Hughes F. R. John son Pe r c i vd &4. Johnstou Prof. Jas. Leeson Dr. W. 13. I,ongstal€>Dr. G. D. Lowe Geo. MGregor Dr. Rob. 3I:tcintosh C11as. Mi.rcer J ,b n . >Iiller Prof. W. H. Illoody Col. Thos. Musliet David. Paris Dr. J. A. Pattinson 13. I,. Pearsall Thos. L. Penny Prof. F. Pepjs JV. H Phillips Riclisrd. Play fair Dr. LYOU. POIrett Robert.Potts Dr. I,. H. ]lees Dr. G. 0. Ileitl Dr. D. 130swcll. Richardson Thos. Scanlan Maurice. Sinks Wive. Smith Denham. Solly E. Jun. Stenhuuse Dr. J. 'raylor Richard. Tcnnant John. Teschcmacher E. F. Thoiiiso~i,Dr. Thos. ?'honi>on Dr. It. 1). Turner Dr. Wilton. IVaringtan Rob. West Win. CVheeler~Jas. Lowe. Wilsoii John. Wilson Dr. G. Yorkc Col. P. ASocicty of Arts LTliwc?t %MA 18 1.1. The miiiutes of the previous meeting having been read and colt- firnicd the report of’ the Provisional Coiiiniittee was brought up and adopted with ainentlnients for the prosetit government of the Socicty. The following gentlemen were tlieii elected as Officers and Council for the ensuiiig year :-~-’1.csi~leiLr.-Prof’cssorT.Graham. I.’ice-Presine/!ts.-I’rofessor W. T. Brande ; J. T. Cooper Esq. ; IhfesSor J. F. Daniel1 ; Rich. Pliillips Esq. Trects rc rer.-Ar t ti ur Aikin Esq. Secretciries.-E. F. Tcscheinacher ; Robert Warington. Cocu~cil.-Dr. T. Clark ; Professor J. Cummine; ; Dr. C. Dau-beny ; Thonias Evwitt Esq. ; T. Griffiths Esq. ; W. R. Grove Esq. ; H. Hennell Esq. ; G. Lowe Esy. ; Professor W H. Miller ; W H. l’epys Esq.; Rob. Yorrctt Esq.; Dr. G. 0. Ilees. April 13.-The President in the Chair. The following are abstracts of the papers which were read :-1. “On the Preparation and Formation of Yellow Yrussiate of Potash,” by Professor Liebig. In order to explain tlie reaction between animal matters and carbon- ate of potash when fused together at a red heat which gives rise to this salt it is necessary to keep in mind the following properties of the salt When heated to redness in a close vessel ferrocyanide of potnssiunl is deconiposed into cyanide of potassium carburet of irou and iiitro- fen gas; that is looking upon the ferrocyanide of potassiuiri as a double cyanide the cyanide of iron is converted into carburet of iron and nitrogen gas while the cyanide of potassium escapes de-composition.The cyanides of metals in general which can conibine with carbon are decomposed in the same way as the cyanide of iron ; thus the cyanide of silver when heated gives at first a little cyano- gen but afterwards it fuses and glowing suddeiily gives nitrogeii gas the carbon remaining in combination with the silver.The addition of carbonate of potash to the heated f’errocyanide of potas- sium prevents the decomposition of any cyanogen cyanide of potas-sium being then formed together with oxide of iron; and when charcoal forms a third ingredient of the fused mixture the oxide of iron is reduced to the rnetallic state. Hence ferrocyanide of potw- sium cannot be supposed ready formed in the red-hot mixture of the iron pot in which it is manufactured that mixture containing both charcoal and carbonate of potash. A general view is then taken of the proccss of manufacture of this salt. Animal substances such as dried blood horn hoofs and bristles with common pearlashes arc) tlie materials employed. The aniinal niattcr is used either in its natural state or it is previously submitted to distillation as in the pwpnration of anitnoilia and the 3 residual charcoal merely employed for the manufacture of the prus- siate.The projection of animal matter into the melted potash oc- casions a lively effervescence from the evolution of carbonic acid and some combustible gases. The liquid is stirred after each addi- tion of the materials. The usual proportions eniployed are equal parts of pearlashes and aninial matter or ten parts of the former and eight parts of carbonized animal matter. Three or four per cent. of iron filings are usually added to the mixture. After each addition of animal matter the heat is urged until the whole is fused and the melted material which is of a thick consistence is iiot re- moved from the pot until the charcoal is sew to be equally diffused through the whole mass.The mass after cooling is placed in ail iron pan filled with water the clear liquid after a time drawn 0% and water boiled several times on the insoluble residue. The liquids are evaporated for crystallizing the salt at a temperature not exceed- ing 203' Fahr. The formation of prussiate takes place after the solution of the melted mass by the action of the matters dissolved upon the insoluble residue ; for this melted mass yields nothing but cyanide of potassium to alcohol and contains no prussiate. In ex- planation of the formation of. cyanide of potassium in the melted mass it is stated that metallic potassium readily produces that salt when fused with calcined blood disengaging at the same time a considerable quantity of' charcoal ; the proportion of nitrogen to carbon in cyanogen being one equivalent of the first to two of the last while in bhod hair and horn the proportion is 1 to 6.Kow when these animal matters are fused at a high temperature with potash the free charcoal reduces the potash tb the state. of potas-sium ; the latter then acts upon the azotized carbonaceous matter forming cyanogen with which it unites. A second mode in which cyanide of potassium is produced is when ammoniacal gas is con- ducted over a mixture of carbonate of potash and charcoal at a red heat. This is accounted for by the action of ammonia upon cliar- coal alone at a red heat ; the gas is entirelF converted into hydro- cyanic acid and hydrogen (N H and 2 C =H N C and 2 H).Now hydrocyanic acid decomposes carbonate of potash at a red heat forming cyanide of potassium. Hence the product of cyanide of potassium is most considerable when the aninial matter is used in its natural state and not previously carbonized a fact of which the manufacturers of prussiate of potash have long been aware from experience. To account for the subsequent conversion of the cyanide of potassium in the process into prussiate it is absolutely necessary that iron exist in the fused mass ; but it may indifferently be in the condition of metallic iron the protosulphuret or the protoxide of iron. The first is readily dissolved by a solution of cyanide of potassium with evolution of hydrogen gas (3 K Cy with H 0 and Fe =2 K Cy Fe Cy and K 0 and H); the second with the formation of sulpliuret of potassium and the third with that of caustic potash.When the iron is added in the state of protosul-phate to a solution of cyanide of potassium one third of the latter salt becomes cyanide of iron (a browii insoluble matter) which is dissolvcd by the other two-thirds of the alkaline cyanide and the ferrocyanide formed. These processes are not altered in the slightest degree by mixing caustic potash or its carbonate or the sulpliuret of potassium with the solution of cyanide of potassium. Much of the iron necessary it is well kiiomn is derived from the corrosion of the iron pot in which the fusion is conducted.Professor Liebig assigns an importaut place to the sulphur of the siilphate of potash usually present to the extent of 12 or 16 per cent. in pesrlashes in effecting this corrosion. In the decomposition of the sulphate of potash by charcoal bisulphuret of potassiiun is formed and carbon- ate of potash. Thus 2 SO,-t2 K 0aiid 4CtKS and KO C 0 with2 C 0,and C 0. The bisulphuret of iron assumes an atom of iron either from the sides of the iron vessel or from iron filings which are added ; the double sulphuret thus formed is very fusible and will corisequently be equally diffused through the mclted mass. The deficiency of product which frequently occurs in the manu- facture of prussiate of potash is ascribed principally to two causes lst to the want of iron in the fused niass.The cyanide of potas- sium is then instead of being converted into ferrocyanide when thrown into water,'dtcotnposed by thc free caustic potash when heat is applied to its solution. Uniting with the elements of water its cyanogen is converted into formic acid and ammonia NC K and 4H 0 =C2H0 + KO and NH,. This destruction of thc cyanide may be avoided by adding iron or its sulphuret to the ley or better the protosulphate of iron. Another cause of loss of cyauitle in the pot itself is poirited out. The bisul- phuret of potassium yields sulphur to the cyanide of potasium and coiiverts the latter into sulphocyanide of potassiuni. But if the irrixture contain a quant.ity of iron suficient to unite with all the sulphur the forination of sulphocyanide will be prevented.Indeed sulphocyanide of potassium itself is decomposed by iron at a high teniperature and resolved into sulphuret of iron and cyanide oP potassium. It is thus seen that by increasirig the proportion of iron the formation of sulphocyanipe is at once prevented and sulphuret of iron offered in quantity more than suficient for its solution after- wards by the cyanide of potassium. The quantity of iron necessary to add in the tusion varies from 22 to 20 per cent. with the pro-poitioil of sulphate of potash in the potashes used. If a sulpho-cyauide appears in the mother liquors the proportion of iron must bc increased. The only remaining condition for the forination of ferrocyaiiide of potassiuni is the coiiiplete exclusion of air during the fusion.Cyanide of potassium cannot be kept in fusion exposed to air without absorbing oxygen arid being converted into cyanate of potash ; hence the advantage which English manufacturers de- rive from cffecting this fusion in close vessels. Cyanate of potash may also be produced by the action of' cyanide of' potassium upon the sulphate of potash existing in thc potashes sulphuret of potas- sium being at the same time f'onned. Now cyanate of potash is 5 decomposed by the application of heat to its solution iiito carbonate of potash and ammonia. The ammonia which escapes during the evaporation of the ley may therefore come from this source as well as from the decomposition of cyanide of potassium by potash already adverted to.2. “On the Formation of Mellon,” by Mr. E. A. Parnell of Uiii-versity College. This paper referred to the decomposition which occurs in the process for niellon from the substance considered by Liebig to be the isolated radical of the sulphocyanides (as obtained by the action of chlorine or nitric acid on sulphocyanide of potassium) ; for which substance having previously shown it to contain hy- drogen and oxygen in addition to the elements belonging to the true sulphocya~iogen the author proposes the term nwtasulpliocyano-gen. It became necessary therefore to seek for other products of the decomposition of this substance than those hitherto recognized narnely niellon sulphur and bisulphuret of carbon ; and in decom- posing pure and dry metasulphocyanogen by heat water sulphu- retted hydrogen and hydrosulphocyanic acid in addition to the above were detected.Admitting the formula for metasulphocya- nogen S, Cy H 0 to which he has been led by analyses the de- coniposition is explained as follows :-Three equivalents of meta- sulphocyanogen containing S36C, N, H 0, are resolved into four of niellon C, N, ;two of hydrosulphocyanic acid S C N2H ; four of sulphuretted hydrogen S H ; eight of bisulphuret of car-bon s,,C ; twelve of sulphur and three of water H 0,. The sum of the elements of these compounds will be found to comprise S, Cs6 N, H 0 ; or three equivalents of rnetasulphocyanogen. April 27.-Thc President in the Chair. A donation of five guineas from Dr.W. B. Leeson was presented to the collections of the Society. The following communications were read :-3. An extract from a letter from Mr. M. Scanlan of W’olver- hampton describing the appearance of flashes of light observed during the crystallization of nitrate of strontian in the dark. 4. “On some of the Products of the Action of Nitric Acid on Castor Oil,” by Thos. George Tilley Esq. (See Memoirs Vol. I. Art. 1.) 5. ‘(On Bleaching Salts,” by M. Detmer Esq. (See Memoirs Vol. I. Art. 2.) 6. The following Note ‘“Onthe Preparation of Chlorate of Potash,” by Professor Graham. It is well known that the ordiiiary pro- cesses for this important salt are attended with some practical diffi- culties. When a stream of chlorine gas is passed through a strong solution of carbonate of otash the absorption of the gas is rapid and complete till one-half of the alkaline carbonate is decomposed ; 6 but the remaining portion which is in the state of bicarbonate is not so easily acted upon.To decompose the latter salt completely chlorine must be applied in excess and the decomposition is attended by the formation of free hypochlorous acid as has beer] proved by Mr. Detmer. The lipid is also at the end highly bleaching and contains much hypochlorite of potash. The boiling necessary to convert the latter into chlorate of potash and chloride of potassiuin occasions according to M. Morin a considerable loss of oxygen and thus lessens the product of chlorate. When a strong solution of caustic potash is substituted in this process for the Carbonate the absorption of chlorine proceeds witliout interruption ; but the liquid when saturated bleaches strongly from hypochlorite formed.A long-continued boiling is required to destroy this property com-pletely and as oxygen escapes the chlorate obtained iiiust be de-ficient in quantity in a corresponding proportion. The process which the author recommends and which is attended with none of these inconveniences consists in mixing carbonate of potash inti- mately with an equivalent quantity of dry hydrate of lime and ex-posing the mixture to chlorine gas. This mixture although quite dry absorbs the gas with prodigious energy the temperature rises much above 212O and water is freely evolved. When saturated it may be moderately heated which destroys a mere trace of hypo-chlorite it contains.The whole lime is found in the state of car-bonate and the potash as chlorate and chloride of potassium. The solution of the two latter salts is neutral without any bleaching property and free from lime. The chlorate of potash may be crystallized from it in the usual way. Carbonate of potash when moistened and exposed to chlorine witbout the hydrate of lime ab- sorbs the gas with great avidity and certainly answers better than a strong solution of the same salt; but the absorption becomes slow after the salt is in the state of bicarbonate and subsequently a large quantity of the bleaching hypochlorite of potash is produced. In the new process described above there is no reason to believe that the carbonate of pctash is decomposed by the dry hydrate of lime till the chlorine is presented to the mixture; then while the lime attracts the carbonic acid the chlorine acts simultaneously upon the potash and the carbonate of potash is thus readily decom- posed.The same principle of calling in a secondary agency to promote combination may be taken advantage of in many other cases. One of these of some interest is the promotion of the ab- sorption of sulphuretted hydrogen by hydrate of lime through the influence of other salts. Thus hydrate of lime dry or slightly damped ceases to absorb sulphuretted hydrogen long before it is saturated with that gas ;but if mixed with an equivalent of hydrated sulphate of soda the absorption takes place with grcatty increased avidity and goes on till two equivalents of sulphuretted hydrogen are taken up for one equivalent of lime.But here with the assist- ance of sulphuretted hydrogen the hydrate of lime decomposes the sulphate of soda sulphate of lime being formed while caustic soda combines with the sulphuretted hydrogen. 7 The author has found that the last mixture may be applied with advantage from its great absorbing power in purifying coal-gas where the highest degree of purification is desirable and where the products sulphate of lime and hydrosulphuret of sulphuret of sodium caan be economically applied. He recommends it to be introduced into the last of the dry lime-purifiers. 7. An extract from a letter fromOlliveSims Esq.Shelton Stafford- shire Potteries was read announcing a considerable and very access- ible source of the hitherto very rare mineral phosphate of yttria. The crushed cobalt ore from Johanmsberg in Sweden when con- verted into ziiffrc or dissolved by acids leaves a yellowisli iiiineral ill crystalline grailis iii the proportion of about one potind avoirdu-pois from one thousand pounds of ore. This iiiineral is the phos- phate of yttria. It may be decomposed by fusion with alkaline car- bonates or by boiling with pretty strong sulphuric acid. May 1 1.-The President in the Chair. Lectures on Agriculture by C. Daubeny M.D. was presented by the author. The following gentlemen were elected members of the Society -J. AM.Heath Dr.H. B. Jones and F. Watkins. The following is an abstract of a paper which was read :-8. ‘‘ On a Simple and Cheap Method of preparing Hydrochloric Acid absolutely pure and of any required strength,” by Wm. Gregory M.D. Professor &c. King’s College Aberdeen. Much difficulty is experienced in procuring pure and concentrated hydrochloric acid for chemical purposes the common commercial acid containing various impurities particularly sulphuric and sulphu- rous acids free chlorine chloride of iron and sulphate of soda ; these arise from impurities contained in the materials employed ; the chlcrine from the action of nitric or nitrous acid (often present in oil of vitriol) on the hydrochloric acid; sulphurous acid from or- ganic particles in the common salt employed ; and chloride of iron from the presence of that metal also in the salt.Pure and clean materials are therefore the first requisite for a pure acid. Dr. Gre-gory finds that if to one equivalent of salt two equivalents of sulphu- ric acid diluted with a certain quantity of water be used instead of one equivalent as usually prescribed the whole of the hydrochloric acid may be expelled without a trace of sulphuric acid passing ol-er even into the first condensing bottle and that two-thirds of the hydro- chloric acid distil over before water is volatilized ; on this observation the following process is founded. Into a common Florence flcwk are introduced 4oances of the pu- rest patent salt and 5 fluid ounces of sulphuric acid of specific gra- vity 1.600 ; c?.gentle heat is applied and the gas which is then gene- rated is conducted by a bent glass tube iiito a four-ounce phial con- taining 2 ounces of distilled water surrounded with snow or ice-cold 8 water. No safety tube is required as the tube is made to dip only about one-eighth of an inch into the water SO that should any absorption take place the rise of a little water in the tube exposes the extremity of it so as to admit the air ; or for greater security a small bulb may be blown on the descenJing limb of the tube. The gas is absorbed as fast as it comes over and for the first hour and one quarter the heat hardly requires to be increased ; if the tem- yerature of the surrounding water has been kept so low as 50° the 2 ounces of distilled water will have increased in volume to 3 ounces of colourless hydrochloric acid fuming strongly and having a spe- cific gravity of 1-20to 1-21 the gas passing over so dry that no part of the tube becomes warm.This portion being removed its place is supplied by 2 ounces more of distilled water atid the heat gradually increased and continued for an hour longcr; by that time all the hydro- chloric acid is expelled with some water and the 2 ounces of water have become 3 ounces of hydrochloric acid of specific gravity 1.10. Both portions are absolutely pure. If 3 ounces of water are used in the first instance 4.5 fluid ounces of acid of specific gravity 1* 165 are obtained ; and then replacing the acid by 2 ounces of water 3.5 ounces more of specific gravity 1.065.If 5 ounces of water are used at once for condensing the acid and kept till the distillation is com-plete 7.5 fluid ounces of specific gravity 1.155 are obtained. Dr. Clark finds sulphuric acid of a specific gravity of 1-65 to answer still better than acid of 1.60. 9. Dr. Clark then exhibited to the Society his method of ascer-taining quantitatively the comparative hardness of water by means of the common test of tincture of soap illustrated by experimental evidence to prove the accuracy of which it was susceptible and the facility of its application. Dr. Clark hoped at a future meeting to lay before the Society more matiire details of the method exhibited. May 18.-Thc President in the Chair. Thc following were elected menibers of the Societv :A.Y.Chabot Dr. J. H. Gilbert Dr. Wm. Gregory George Shith Pro- fessor J. J. Sylvester John Ward Win. Wegg ; and R Murray E. A. Yarnell J. H. Pepper Associates. 10. A4n extract of a letter from Mr. Maugham was read ''On the Mode of treating Copper Ores and the Ores of other Metals com- bined with Sulphur so as to ascertain the quantity of Sulphur in such Ores and also the quantity of Copper in the native Sulphuret." A quantity of the powdered ore sulphuret of copper about 50 or 100 grains is placed in a porcelain tube tmversing a small furnace and made red-hot ; after remaining for3 or 6 minutes a portion of the sulphur will be expelled ; tl stream of oxygen gas is then passed over it the remaining sulphur is then rapidly given off as sulphurous and sulphuric acids and the copper thoroughly oxidized.By heating the 9 ore when first introduced into the tube it becomes slightly adherent which prevents any of it from being blown away by the oxygen gas. The contents of the tube are then removed into an assay crucible with the addition of black flax and a little charcoal ; the whole co-vered with dry carbonate of soda or borax and submitted to a yeHow heat when a button of copper is obtained. Mr. Maugham finds that arsenic and other volatile met.& that may happen to be present are oxidated and expelled by the heat; but should tin be present it will be found with the reduced copper and must be removed in the usual way. The process is known to be complete when no more vapours are seen to issue from the tube or when the odour of sulphu- rous acid is no longer perceptible.It is however to be observed that white vapours will be seen even after the process is cornplete owing to a portion of sulphuric acid condensed in the tube returning to the hot part. An assay of this kind takes about twenty minutes to execute. When the wet analysis is desirable we have only to proceed as before in the tube part of the process and to dissolve the residue in the proper acids. Mr. Maugham speaks favourably of the use of chlorate of potash added to hydrochloric acid for dissolving certain ores where nitro- muriatic acid is generally employed and afterwards expelling the ex- cess of chlorine by heat ; the known inconveniences of nitric acid in certain cases are thus avoided.The quantity of sulphur contained in the ore is ascertained by elongating the tube traversing the furnace so that it may dip into a vessel containing water saturated with chlorine by wliicli meiiiis the sulphurous acid is converted into sulphuric acid and the quantity of sulphur found from the precipitate with chloride of barium 11. A paper was read ‘‘ On the Atomic Weight of Carbon,” by Professors Redtenbacher of Prague and Liebig of‘ Giesscn. (See Memoirs Vol. I. Art. 3.) June 1.-Thc Presidtwt iii the Chair. Professor J. Liebig was elected a Foreign Member of tlic Society. Dr. B. Babingtan M. Detnier George Hallet H. Inglis, T. W. Reid Jas. Tennent T. G. Tiiley John Wilson werc clectetl Members and Win.Francis Associate. The following coniinunications were then read :-12. Extract of a letter from Col. Yorke “ On a Specimen or Arti-ficial Arragon ite.” ‘‘This substance was taken from the interior of a copper boiler which was used to supply hot water for household purposes ;it Port Eliot Lord St. Germaine’s seat in Coriin.al1. ‘l’hc substance is about hths of an inch thick and by its non-conducting power it caused as I understood the destruction of the boiler. On the surface which was next to the copper it is coated by dioxide of copper. and the Chern. PTOC.-NO. 1. 10 mass appears made up of an aggregation of prismatic crystals whose axes are perpendicular to the surface on which the incrustation formed under a microscope these crystals appear to be six-sided prisms.I compared under a .polarizing microscope portions of the powder of Iceland spar and of arragonite from Bilin with the pow- der of the specimen ; the latter agreed very closely in appearance with that of arragonite. "Among the powder of the specimen were seen some very acute double six-sided pyramids; these with little doubt are similar to those formed by G. Rose by evaporating solutions of carbonate of lime at a boiling heat and described by him as resembling some snpphirc crystals. " On chemical examination it was evident that the specimen con- sisted chiefly of carbonate of lime ; water howevcr dissolved from it a small quantity of sulphate of lime. "The following is the result of an analysis made on 10 grains but which does not pretend to minute accuracy :-Matter insoluble in muriatic acid silica with } oxides of iron and copper.1.3 Sulphate of lime ........................ 1.8 Carbonate of lime.. ...................... 93.3 Carbonate of magnesia.. .................. 3.2 100 "Deprived of its coating of dioxide of copper three trials were made of the specific gravity of its powder ; the sulphate of lime being previously washed off with hot water. "The two first trials were made by weighing about 80 grains of the powder in a small spherical-stoppered phial (whose contents in di- stilled water at 62' was previously determined) and then when filled up with water the third trial was made in the manner described by Rose.The specific gravity being thus determined the powder was in each case dried and slightly ignited (by which operation arrago- nite as is known is converted into calcareous spar) and the specific gravity again taken. The results were as follows :-Spec. Grav. Spec. Gray. Ixfore ignition. after igmtion. 1st trial ...... 2.842 2.708 2nd .......... 2-828 2.701 3rd.. ........ 2.878 2.6S1< --_ Mean.. ........2*849 2 696 The specific gravity of arragonite crystals from Bilin is 2.946. "The highest specific gravity which Rose obtained of arragonite famed by evaporating solutions of carbonate of lime he states was =2.836'. ''Specific gravity of €celand spar is 2-72. I should suppose then that there can be little doubt but that the specimen affords an examplc * The loss by ignition on 43.8 grains was =.08 grains.of the formation of arragonite and a verification of G. Rose’s expe- riments. ‘‘ I have since made two attempts at producing arragonite by Rose’s method of precipitation but cannot boast of my success. The fol- lowing is a note of the best experiment. A solution of 300 grains of chloride of calcium in 4 ounces of water at 212’ was mixed ra- pidly with a solution of 330 grains of carbonate of ammonia in 8 ounces of water at 180’. The mixed liquor was not alkaline. ‘‘The precipitate under the microscope consisted chiefly of radiating epicular crystals extremely minute with occasional rhombohedrons. The precipitate being washed the specific gravity taken before dry- ing came out = 2.751 after drying it was below 2.7.During the washing a slight crackling noise was heard and I cannot help think- ing the precipitate may have been thrown down as arragonite but changed into calc-spar during the washing and drying.” 13. Professor Kuhlman of Lille presented specimens of Chalk hardened by his process for the Silicification of Limestones which consists of immersing them in a solution of silicate of potash ex- posing to air for several days and afterwards washing. Although the chalk did not contain more than three or four per cent. of silica it was capable of scratching many cementa and marbles. In a similar manner he could harden carbonate of lead and plaster.of Paris. He finds alkaline salts in all the limestones containing silica which are hydraulic and believes that they originally resembled ordinary chalk in purity but have been partially silicified by infil- tration of water containing an alkaline silicate in eolution or by a natural process analogous to his artificial one.14. Extract of a letter from Dr. R. F. Marchand of Berlin ‘‘ On the Atomic Weight of Carbon.” ‘‘ I take this opportunity of communicating the results of experi- ments relative to the atomic weight of carlion which Professor Erd- man and myself have very lately obtained. The difference between the numbers recently given by Dumas and that of Berzelius was a sufficient inducement for us to examine and repeat Dumas’s experi- ments much occupied as we are with organic analysis.The burn- ing of diamonds in oxygen gas was easily effected by us in a porce- lain tube by a pretty high temperature. The apparatus employed was very similar to that described by Dumas. ‘I The following are the results :-No. 1. 0.8062 gramme diamonds left a residue weighing 0.0010 gmmme and gave 2.9467 gr. carbonic acid consequently giving the atomic weight for carbon 75-19. No 2. 1.0867 gr. left a residue weighing 0*0009 gr. and gave 3.9875 gr. carbonic acid = carbon 74.84. No. 3. 1.3575 gr. left a residue weighing 0.0018 gr. and gave 4.9659 gr. carbonic acid = carbon 75.10. No. 4. 1.6330 gr. left a residue weighing 0.0025 and gave 5.97945 = carbon 74-98 No. 5. 0.7510 gr. left a residue weighing 0.0010 and gave 2-7490 = carbon 75.03.“ Graphite gave the same numbers ; the residues were pure white silex without a trace of oxide of iron :-No. 1. 1.4580 pmme native graphite left a residue weighing 0.0075 and gave 5*31575 gr. = carbon 75.05 atomic weight. No. 2. 1.5746 gr. graphite left a residue weighing 0.037 and gave 5.6377 gr. = carbon 75.02. No. 3. 1.6578 gr. residue 0*0084 and gave 6.0385 = carbon 75.1 8. No. 4. 1.9040 gr. artificial graphite residue 0.0105 gr. gave 6,9355 gr. =carbon 75-10. “ The mean of these experiments give 75.07 ;we therefore consider 75 as the true number indicated by thesc experiments for the atomic weight of carbon. It is remarkzhle that this number was fixed upon theoretically by the English chemists and Iias now been confirmed by experiments.If we take the number 6.1239 for hydrogen with a very small increase viz. as G.250 we arrive at the numbers for oxy-gen carbon and hydrogen viz. 16 12 2 or 8 6 1.” 15. A paper was rcad “ On Malic Acid and the Salts of Rlalic Acid,” by R. Hagen. (See Memoirs Vol. I. Act. 4.) 16. A paper was read On Yyroxylic Spirit,” by Andrew Ure ‘I M.D. (See Memoirs Vol. I. Art. 5.) The Society then adjourned till Tueiday the second of November next. 13 November 2 1841.-The President Professor Graham in the Chair. Mr. Wm. Hasledine Pepys presented to the Society Specimens of the Nut of Phytelaphas decandra or vegetable ivory in the natural and wrought states. Mr. R. Taylor presented his Calendar of the Meetings of Scientific Bodies of London for the Years 1841 and 1842.Mr. Griffin presented his piiblished List of Chemical Apparatus &c. The following gentlemen were elected members of the Society :-James Beaumont Neilson John Sylvester Angus Croll Wm. Pot- ter Thomas Hawkesleg and Thomas De la Rue Esquires. The following communications were read :-17. An extract of a letter hrn M. Dumas '< On the Analysis of Atmospheric Air." The method of analysis adopted in these experiments was to cause the air under examination to pass through the combustion tube employed in organic analysis charged with reduced metallic copper into an exhausted flask and then weighing the resulting oxide of copper and the nitrogen in the A;&. M. Dumas says ''You may be assured that no combination of nitrogen with copper is formed in the circumstances under which we operate a decided red heat being used ;besides all our analyses agree as you will be able to judge by the following numbers :-By weight."April 27th 1841 2292 oxygen in 10,000 of atmospheric air. .... 2s .... 2309 ........ .... 29 .... 2304 ........ May 29 July 20 .... 22 .... 2301 .... 2503 .... 2300 ........ ........ ........ during heavy rain. during rain,at 1 P.M. 12 P M. clear. .... 24 .... 2305 ........ 12 A.M. cloudy. 'r Thus the three first figures expressing the proportion of oxygen contained in the air are constant the fourth figure variable. I do not consider however that the whole of this difference can arise from errors of observatioii; it is a subject requiring still further examination.MM. hlelloni. and Piria are performing the same experiments at Naples by the same means ;and also M.Stas at Brussels. M. Levy who has assisted in the above experiments in- tends to repeat them in Denmark." M. Dumas urger the repetition of these experiments to be made at various times and in various places a11 over the world to whicli the English chemist has more easy access than others in order to resolve this curious physical problem. "The density of nitrogen nppenrs to me," he adds ''to be be- tween 0.970 and 0-973. That of oxygen with which we have been particularly occupied and upon wiiich we have made twenty dif-ferent experiments is always found comprised between 1-105 and 1.108 ;it appears to be reprcseiited very nearly by 1.106'.That of Chem. Proc.-No. 11. B 14 carbonic acid has varied between 1.526 and 1.528 ; if 75 is adopted for the atom of carbon then oxygen is condensed some thousandths in forming carbonic acid. “ The density of hydrogen is always found above 0.0691 it has varied between 0.0692 and 0.0696 ; we have operated on quanti- ties of about 17 litres of this gas. As to the composition of water by weight which has occupied me personally during nearly two months and on which I am still experimenting I remain doubtful. I have never found less than 12.50 for the equivalent of hydrogen and often 12.55 and at present I cannot choose between them. In adopting the first of these numbers no error of any practical conse-quence can result but as a philosophical question I take so hi@ an interest in it that I shall continue my experiments until they lave no doubt on the subject.” 18.“ On the Analysis of Cetine and Ethal,” by Dr. John Sten-house. (See Memoirs Vol. I. Art. 7.) 19. “ Notice on the Artificial Magnetic Oxide of Iron,” by Tho-mas Starkey Thornson Esq. After adverting to the procese given in the last edition of Tur-ner’s Elements of Chemistry for the preparation of the artificial magnetic oxide of iron the discovery of which is attributed to Abich and Gregory Mr. Thornson says ‘‘ Recollecting that this oxide had been produced some years ago by a process surprisingly similar to that of Dr. Gregory I corresponded with the inventor of it Mr. John Mercer one of the original members of this Society and part- ner in the firm of Fort Brothers and Co.calico-printers from whose letters I extract the following remarks :-‘ This. substance was pre-pared by me in 183 1 and in 1833 applied extensively as a medicine with great success. Mr. Gossage of the Stoke Prior Alkali Works who was staying with me at that time for a few days was so im-pressed with its value as a medicine that upon his return home he wrote to me for a quantity of it to send to his friend Dr. Jephson of Leamington to whom I forwarded a quantity with the receipt for its preparation and the dose. lhis receipt was published by Dr. Jephson and given away among his friends; Dinneford was also employed to make it and also an agent for the sale of it in Man-Chester.’ ” The following is Mr.Mercer’s mode of preparing this oxide -“ Take a quantity say one pound of the common crystallized pro- tosulphate of iron dissolve it in water and add nitric acid in sufficient quantity to peroxidize it and afterwards expel carefully all excess of nitric or nitrous acid by boiling. Tothis add one pound of protosul- phate of iron with water sufficient for its solution. Pour the mixture iuto a solution of caustic potash sufficient in quantity and strength to decompose the whole and then boil. The precipitate thus thrown down consists of a mechanical mixture of the protoxide and peroxide of iron atom to atom ; raise the temperature of the mixture to 212O Fahrenheit and their chemical union is effected.That such is the succession of changes is proved by dipping into the mixture pre- 15 vious to boiling it a piece of clean cotton cloth which after ex- posure to the air for a few minutes and washing in water exhibits the buff stain peculiar to peroxide of iron precipitated upon cotton fibre. But if this is performed after the boiling a dirty black stain is obtained indicating the formation of the black oxide.” This fact is further proved by the oxide after boiling having a crystalline structure when examined under the microscope the minute plates having a brown colour and being transparent although the edges of the crystals are not sufficiently defined to trace the form. Mr. Thomson adverts to the application of the artificial magnetic oxide of iron either in a dry or moist state suspended in water as a substance well adapted from its extreme susceptibility of mag- netic influence to indicate the direction of magnetic or galvanic currents the magnetic curve described by Dr.Brewster being beau- tifully exemplified by the use of this oxide. 20. “ On the Influence of Water in Chemical Reactions,” by Mr. E. A. Parnell. November 16.-The President in the Chair. Dr. Hare of Philadelphia presented to the Society several copies of his papers *‘ On Tornadoes,” “Chemical Nomenclature,” ind Some Experiments to ascertain the Heating or Cooling Influence of Changes of Density resulting from Changes of Pressure in Dry and Moist Air,” &c. Dr. Charles Schaf haeutl was elected a member of the Society.The following communications were read :-21. ‘I On the Analysis of the Oils of Laurel Turpentine Hyssop, and Assafetida,” by Dr. John Stenhouse. (See Memoirs Vol. I. Art. 7.) 22. An extract from a letter from Dr. Clark “ On the Revision and more exact Determination of Atomic Weights.” Dr. Clark finds that when the proper correction for weighing in a vacuum instead of in air is applied to the weighings made by Berzelius in his experiments on the formation of water by passing hydrogen gas over ignited oxide of ccpper the results are very sen- sibly altered. ‘‘ Berzelius gives ‘‘ Copper (metal) 395.6 Water produced Peroxide of copper 495.6 ... Increase oxygen 100 Hence ;;drop 12.49 But if weighed in a vacuum the increase of 100 for oxygen and the weight of 112.491 for water would both have been greater.The following would be the corrected numbers :-oxygen 100.0266 ; water 113*G13; or oxygen being 100,water will be 112-583. Hcncc 16 hydrogen 12.583 in air 12.491 correction + 0.092. As to Berm- lius and Dulong’s experiments on the specific gravity of gases how- ever strange it is true that the results appear almost all to have been miscalculated. The specific gravity of hydrogen instead of being calculated 0.0687 should have been 0.06986 or with Rud- berg’s dilatation 0.06988. With the received specific gravity of oxygen this would give 12.67 for the equivalent of hydrogen; Dumas’s specific gravity of oxygen would give 12-64. On all these considerations I regard the numbers authorised by the experiments where Berzelius has taken part to be 12.6 for hydrogen.” 23.“ On a more simple and correct Mode of Reducing the Indi- cations of the ordinary Saccharometer and Hydrometer to each other,” by Robert Waringtou Esq. The great utility of some ready means of effecting these opera- tions was first pointed out on the following grounds:-lst from the great variety of saccharometers in general use ; 2ndly from their being constructed of brass which from its liability to loss of weight from abrasion and corrosion causes frequent errors of indication ; 3rdly from some of these instruments as in that employed by the Excise reading off degrees of specific gravity of which the saccha- rometer equivalent is found by referring to a printed table sold with the instrument; and 4thly to the practical chemist from the great cost of these instruments and from his always having in his hands the means of accurately ascertaining the specific gravity of any Pam- ples of worts or other material on which he may be ealled to experi- ment and therefore only requiring a correct formula for reducing such specific gravities to those of the saccharometer.The saccharometer is a hydrometer of great delicacy having its zero point corresponding to the specific gravity of distilled water and its scale which has usually a range of specific gravity from 1.000 to 1.150 divided into 54 principal divisions each of which is again subdivided into 5 or 10 equal parts. The object which is professed to be attained in this instrument is the indicating the number of pounds of saccharine matter contained in “the barrel ” of the infu-sion of malt and other grain.The imperial barrel contains 36 gd-lons of distilled water of 10 pounds each or 360 pounds of water. Of wort whose indication is 1 on the saccharometer a barrel weighs 361 pounds ; 2 on the saccharometer 362 pounds and so on for the 54 divisions of the scale. This instrument does not fulfil its professed object as,-lst it does not indicate directly the absolute quantity of * solid matter per barrel but only the change of density which this occasions ; Bndly it is equally effected by the other ingTedients in the infusion of malt as mucilage vegetable albumen &c. as by its sugar.The eaccharometer must therefore only be regarded as an instrument of comparison. The rule usually followed in calculating the specific gravity from the saccharometer indication is to add 360 the weight of the barrel of water to the saccharomekr indication and then multiply the result 17 by 9-77 ; or 26th~ being the value of each saccharometer pound ex- pressed in terms of specific gravity; 360 multiplied by 2.77’being equal to 1000 the specific gravity of water. Hence if 36 be the observe saccharometer indication the specific gravity is 36 + 360 x 2-77 = 1100. Reversing the operation and dividing the number expressing the specific gravity by 2.77 and then deducting 360 from the result gives of course the saccharometer indication or gravity ; ??,.thus 1100-360 = 36. Many works held in high estimation by way of fachtating this operation have adopted the use of the factor 2.78 but this must of necessity involve error without materially shortening the calculation; some parties have gone so far as to state that 2.7 is a sufEcient approximation ; this however with the gravity taken as an illustration will give an error of 11.4 pounds in excess or 47.4 instead of 36. The rule adopted by the author for converting real specific gmvities or hydrometer indications into saccharometer gra-vities is as follows :-From the specific gravity observed expressed in terms of distilled water as unity deduct 1 and then multiply the result by 360 ; the product is the equivalent saccharometer indication ; thus for specific gravity 2*100 ; 1.100-1.000 x 360 = 36 of the sac- charometer.The saccharometer gravity again is calculated from the real specific gravity by the converse of this operation; divide the eaccharometer indication by 360 and then add 1 ; thus & + 1-OOO = 1.100. December 7.-Richard Phillips Vice-president in the Chair. Mr. Graham presented his ‘* Elements of Chemistry.” Mr. Porrett presented an agglutinated mass of gun-locks screws gun-flints &c. from the late fire at the Tower of London. Robert Smith Ph. D. was elected an Associate Member. The following communications were read :-24. ‘‘ On a new Class of Cacodyl Compounds containing Plati- num,” by Professor Bunsen of Marburg. (See Memoirs Vol. I. Art. 10.). 25.** On the Preparation of Chromic Acid,” by Robert Waring- ton Esq. In the number of L’lnstitut for 9th July 1840 under the head of Proceedings of the Imperial Academy of Sciences of St. Pe-tersburgh,” a notice is given “On an easy process for preparing chromic acid and the manner in which it behaves with sulpliuric acid,” by M. I. Fritzsche. The author pours concentrated sulphuric acid with care into a hot and saturated solution of the bichromate of potash and obtains a voluminous scarlet crystalline precipitate which is separated and dried first by heat then in a vacuum. This is the chromic acid. which must be washed with a small quantity of cold water to remove the mother liquors and sulphuric acid which 18 riiay still adhere to it.As to the compound of sulphuric acid and cbrornic acids described by M. Gay-Lussac in the Annales de Chin& et de Physipe vol. xvi. p. 102 the author says he has ‘I never hen able to make it and is very much disposed to doubt its existence.” On repeating this process I found that the chromic acid does not fall alone but is contaminated by admixture with a considerable quantity of a white saline substance which on exami-nation proved to be the bisulphate of potash and which on account of the great solubility of both these substances as precipitated there is great difficulty in separating. The modification of this process, which I have found to give chromic acid in a crystalline form and nearly in a state of purity is to take 100 measures of a cold satu- rated solution of the bichromate of potash (prepared by hoiling and then allowing the solution to cool and deposit the excess of the salt) and add to this from 120 to 150 measures of concentrated sulphuric acid ; the latter should be free from sulphate of lead as otherwise it will fall as chromate and sulphate of lead with the chromic acid on dilution with the solution of bichromate.The mixture is then al-lowed to cool and the chromic acid gradually crystallizes in beau- tiful dark crimson needles. Decant the fluid part and place the crystals with the adhering sulphuric acid on a thick fiat tile of bis-cuit porcelain ; another tile is then to be placed upon the crystals and the whole submitted to pressure for a considerable time. On removing the chromic acid it will be found in a perfectly dry state and yielding a mere trace of sulphuric acid on examination.26. ‘‘ On the employment of Chromic Acid as an agent in Gal- vanic arrangements,” by Robert Warington Esq. (See Memoirs Vol.I. Art. 9.) December 21.-The President in the Chair. Dr. Lyon Playfair presented the second edition of Liebig’s ‘‘ Che-mistry of Agriculture.” Henry Beaufoy Esq. Thomas S. Thomson Esq. Henry Croft Esq. William Crawhall Esq. Rev. W. Walton Henry Heynolds Esq. John Barnes M.D. John Hutchinson Esq. Thomas Morti- more Esq. were elected members. The following communications were then read :-27. ‘‘ On the Agency of Caloric in permanently modifying the state of Aggregation of the Molecules of Bodies,” by Warren De la Rue Esq.The subeject of tnis short notice is the practical application of the action which takes place in masses composed of palpable particles when raised to a temperature insufficient even for their partial fusion. In illustration of the particular action alluded to may be quoted 19 the following familiar facts :-Precipitated gold wlien heated to a low red heat contracts in volumc becomes more coherent and yellow in colour ; clay contracts in volume when heated and generally in pro-portion to the intensity of the lieat ; the carbonaceous deposit in the inside of gas retorts by the continued action of heat acquires suffi- cient hardness to scratch glass ; ordinary coke and charcoal become harder the longer the action of heat is continued on them; these and many other analogous facts are examples of a new molecular ar-rangement being produced in vwious substances by subjecting them to an increase of temperature not however sufficient for their fusion.To cause the foregoing changes a red heat is employed ; we shall however presently see that a temperature but little above that of boiling water is quite suficient to materially alter the cohesion of some substances. It may be as well here to premise that the particles should be brought as closely as possible together ; to effect this if the sub- stance be in powder it must he made into a paste with water to displace the air and the paste so prepared submitted to a pressure of four tons or upwards on the square inch ; air being so exceedin4 compressible it cannot be got rid of without the use of some liquid.The manner of pressing need not here be entered on the operation being purely mechanical. White lead precipitated by carbonic acid gas from a hot solution of the sub-nitrate always falls as an exceedingly light deposit ; if it be pressed as before described and the pressed cake dried at the or-dinary temperature of the atmoiphere it coheres but imperfectly but on being subjected to a heat of between 200’ and 300’ Fahrenheit it becomes esceedingly hard and compact ; and if the cake be ground up with water and redried it will be found far more dense and opake than the original precipitate showing the change to be permanent. The following fact was communicated to me by hleesrs.Nasmyth and Co. of Patricroft :-Common chalk cannot readily be sawn into thin‘slips as it crunhles under the operation ;if however it be baked at the temperature before named it becomes far more tenacious and may be then cut into any form we choose still heing sufficiently soft for drawing or writing to which purposes it is far more applicable than before baking. Almost all precipitates dry much more crisp at high than at lorn temperatures the agency of heat facilitating the attraction of such particles as may happen to be in contact. In conclusion I may remark that it appears by no means impro-bable that the long-continued action of temperatures but slightly elevated above the ordinary temperature of the atmosphere map have been and still may be the cause of the formation of hard rocks from materials origiiially but slightly coherent.28. “Notice of the Decomposition of Oxalic Methylic rEther (Oxdate of Oxide of Methyl) by Alcohol,” by Henry Croft Esq. While in Berlin I was led to examine the action of potassa on oxalate of methyl by a statement of WeidIuanii and Schweitzer in 20 their first treatise on Wood-spirit; namely that the compounds of the oxide of methyl with acids are decomposed by alkalies not into their constituent acid and wood-spirit as Durnas and Peligot have stated but into the acid and a peculiar oil which they called methol. From this Gwig drew some conclusions unfavourable to the accu- racy of Dumas and Peligot’s research. This statement of Weidmann and Schweitzer I found to be incorrect CUIthey themselves also al- lowed in their second paper.Oxalate of methyl is best prepared by distilling a mixture of 1 part wood-spirit 1 part anhydrous oxalic acid (H 0 $-C,O,) and from ith to Qth of sulphuric acid. The first portion which passes over may be returned and afterwards an-sther part of wood-spirit added or ewn two. The aether obtained must not be allowed to stand in solution for any length of time for it easily decomposes. The above proportions I have found to be the best; the method with oxalic acid alone is troublesome on ac-count of the great volatility of wood-epirit and the length of time required for forming any considerable quantity of the aether. If on the other hand so much as an equal weight of sulphuric acid is taken the mixture becomes brown or black and towards the end of the operation sulphurous acid methol and other products are formed.By passing hydrochloric acid gas into a solution of oxalic acid in wood-spirit no aether could be obtained ; it is possible how.- ever that the result of further experiments may be more favourable only one experiment being made owing to the ve y small quantity of wood-spirit in my possession. It is well known that Mitscherlich formed the oxalovinate of PO-hsa by adding to an alcoholic solution of oxalic aether just so much of an alcoholic solution of potassa as was suflicient to saturate half the oxalic acid contained in the aether. As no acid oxalate of methyl is known I therefore attempted to form it in the same manner but owing to the excessively small quantity of spirit which I possessed, and which is not to be obtained in northern Germany I was obliged to dissolve both the oxalic methylic aether and the potassa in alcohol it appearing very unlikely that the alcohol could have any disturb- ing influence as it is only the aether which ought to be decomposed.On adding the solution of potassa until the mixture became slightly alkaline a white salt in pearly scales was obtained ; this was washed with alcohol and dried. The filtered solution gave more of it on evaporation. In analysing this substance it was useless to attempt to determine the carbon and hydrogen owing to the admitted insecureness of the analyses of potash salts and I had not enough material to prepare either the lead or baryta salt.The oxalic acid and the potassa were therefore alone determined it contained,-lst 30*81,and 2nd 30.76 per cent. of potassa and 46.58 of oxalic acid. I’liis agrees very well with the formula for oxalomethylate of potassa plus one atom of water ; but no water could be driven out by a heat of 150’ C. and I at length found that the salt was only oxalovinate of potash with the composition of which the analyses agree very well :- 21 1. 2. Oxalic acid . . . 46.12 46-58 Potassa . . . 30.04 30.76 30.81. The salts agreed moreover completely in their properties. On re-peating the experiment with wood-spirit instead of alcohol I did not obtain an insoluble salt but on evaporation one which is probably the true oxdomethylate of potash and which I am now ahout exa- mining.Such a decomposition as the above is I believe of very rare oc- currence ; I am not aware of any other instance of it being known although the possibility of some such kind of decomposition has not escaped the acuteness of Berzelius. (Lehrbuch,viii. 703.) We may perhaps suppose that oxdomethylate of potash is first formed but that the attraction of oxalic acid for Ether and of oxalic Ether for oxalate of potash is so strong as to cause the decomposition of hy- drate of &her into its elements when the alcoholic Ether will com-bine with the oxalic acid and the oxide of methyl whose place it takes combines with water to form wood-spirit. That some kind of what is called predisposing affinity is here in play is evident from the fact that oxalate of methyl may be boiled with alcohol for hours without any such change taking place.It may be stated in conclusion that the process last described is a very good and oeconomical method of obtaining the oxalovinate of potassa in a very beautiful form. 29. On the Radical of the Cacodyl Series of Compounds,” by ‘c Professor Bunsen of Marburg. (See Memoirs Vol. I. Art. 8.) January 4 1842.-The President in the Chair. Lectures on Agricultural Chemistry and Geology first part by James F. W.Johnston M.A. was presented by the Author. Michael Faraday D.C.L.,Philip Coffey Esq. Durant Quincey Eeq. were elected members. The following communications were then read :-30.#I On some of the Substances contained in the lichens em- ployed for the preparation of Archil and Cudbear,” by Edward Schunck Esq. (See Memoirs Vol. I. Art. 11.) I‘ 31. On a Rc-arrangement of the Molecules of a body after solidification,” by Robert Warington Esq. (See Memoirs Vol. I. Art. 12,) January 18.-The President in the Chair. Charles Thornton Coathupe Henry M. Noad John Philip, Esquirea were elected members. Colonel Yorke exhibited a specimen of a silver ore from Mexico Ckm. Proc.-No. 11. 22 containing bromide of silver from his collection in confirmation of the late discovery by M.Berthier of the existence of bromine in silver ores. ‘I’he following communications were read :-32. ‘‘ On the Conversion of Benzoic Acid into Hippuric Acid in the Animal Economy,” by Mr.Alfred Baring Garrod of University College. (See Memoirs Vol. I. Art. 13.) 33. (‘On the Constitution of the Sulphates as illustrated by late Thermometrical Researches,” by Thomas Graham Esy.,F.R.S. &c. (See Memoirs Vol. I. Art. 14.) 23 February 1 1842.The President in the Chair. Dr. Bunsen Professor of Chemistry in the University of Marburg was elected a Foreign Member of the Society. The following communication was read :-34. ‘‘ On the Change of Colour in the Biniodide of &Iercnry,” by Robert Urarington Esq. (See Memoirs Vol. I. Art. 15.) February IS.-l’he President in the Chair. The Council declared the names of the gentlemen whom they proposed should retire from the Vice-presidents and Council and those whom they proposed for election.George Knight Jun. Esq. was elected a member of the Society. The following comniunicationa were read :-35. “ On a new Oxalate of Cliromiuin and Potash,” by Henry Croft Esq. (See hlcmoirs I’d.1. Art. 16.) 36. ‘‘ Some Observations on Brewing,” by Septimus Piesse Esq. The author’s attention was directed to the subject by the follow- ing inquiry :-“ Is it possible to obtain a greater quantity of extmct from malt by any other process than that usually followed? Is any thing left in the grains which ought to be in the wort ? ” Now from an esamination of several samples of the malt taken when supposed to be completely exhausted and from the circum- stance of the grairis affording such a large quantity of nourishment to cattle I was led to suspect that it was possible to increase the weight of extract; in fact the grains were found to contain a nota-ble quantity of starch.The non-conversion of this starch into sugar does not depend in the cases I have witnessed upon the use of improper temperatures but ariscs from a deficiency of diastase (the principle which effects the change of starch into sugar). In the ordinary process of brew- ing n certain quantity of water and malt are mixed together of a proper temperature. After standing for a time this water or as it is then termed wort is drained from the malt and a second portion of water is run on to forin the second wort. There can be no doubt but the principal portion of the starch is converted during the first mashing but it never is all.Now it must be remembered that as diastase is soluble it is taken up by the first wort and when that is run off the diastase passes away also. ‘l’he improvement consists simply in adding diastase to the second wort to convert the remain- ing starch into sugar. This is done by the addition of a portion of malt (which contains diastase) previous to mashing a second time. In a brewing of 30 quarters I should take 29 quarters for the first mash and add the remaining quarter to the second. There is such an increase as to warrant me in advising its adoption by it11 brewers and distillers. Chert!* Proc.-No. I1 I. 24 Another improvement in brewing is recommended by the author to prevent the absorption of oxygen by the wort and thus in a great measure prevent acidity.The wort as it flows from the tun passes into the underback according to the usual practice where it is exposed to the air ; and that for some time because the wort must run slowly in order to come bright. The improvement consists in having a float in the back that is a surface of wood the size of the bottom of the back upon which it rests when empty. As the wort runs into the back the float rises with it and falls again when it is pumped up to the copper thus effectually keeping it out of the contact of air previous to boiling when the danger ceases. When this precaution has not been taken 1 have invariably found the wort to indicate more or less acid which may be looked upon as likely to lead to sour beer.March 1.-The President in the Chair. A specimen of sulphuret of lead artificially crystallized from the silver smelting furnaces at the Hacienda de Regla lbf exico was pre- sented by Mr. John Phillips. ‘I’he following communications were read :-37. ‘‘ On the Preparation of Cyanide of Potassium and its appli- cations,” by Professor Liebig of Giessen. (See Memoirs Vol. I. Art. 18.) 39. ‘‘ On the Specific Heat and Conducting Power of Building Materials,” by John Hutchinson Esq. The following is the substance of 1Mr. Hutchinson’s paper :-The author after mentioning the state of our knowledge respecting the conducting powers for heat of different substances proceeds to point out an important source of error in all such investigations hitherto made arising from the neglect of correction for differences of specific heat among the bodiea examined ;the effects observed being evidently mbed efects arising from both causes.‘i’liis being the case before any correct investigation of the relative conducting powers of huild-ing materials referred to could be advantageously undertaken it be-came indispensable to acquire a previous knowledge of their relative capacities for heat in order that correction for differences of this kind might be made. Thisinquiry therefore naturally preceding that of the proper subject of the paper first attracted the author’s attention. The building materials selected for experiment were the following -Oak beech and fir-woods; common facing and fire-brick; As-phalte composition hair and lime mortar lath and plaster Roman cement plaster and sand plaster of Paris Keene’s cement ; slate Yorkshire flag-stone Zunelle marble Napoleon marble Portland and Bath-stone ; and lastly three specimens of the stones now used in building the Houses of Parliament.The plan of experimenting chosen was that known as the ‘‘method 25 of mixture,” this appearing by all evidence on the subject to be the most unobjectionable. The process followed differed but little from that described by Itegnault in his recent researches. A suitable quan- tity of material in fragments being accurately weighed out and placed in a little wire basket with the bulb of a delicate thermometer in the midst the whole was exposed in an inclosure heated by steam until the thermometer ceased to rise when the basket was withdrawn and plunged with suitable precautions into avessel of water at a tempe-rature a little below that of the atmosphere.After the lapse of a very short interval the temperature of the water was carefully ob- served and its rise gave the ~=RS of calculating the specific heat of the substance. The author remarks on the necessity of equalizing as much as pos-sible the times of heating of the different substances having observed a great difference in the results given by the same body when slowly and when quickly raised to the high temperature required for the ex- periment and attributes this difference to an alteration in the state of the currents or waves of heat travelling inwards towards the centre of the solid.A number of minute precautions indispensable to a correct result were also pointed out and exemplified. The results of the investiga- tion were given in a tabular form and the principle of the calculation described. With the knowledge thus obtained the author proceeded with his inquiries respecting the conducting powers of the substances under examination. The plan usually adopted in this kind of research namely ob-serving by the aid of thermometers the time occupied by the passage of a certain amount of heat lengthways through the substance of a prism one end of which was exposed to a high and constant tem- perature having failed on trial with these bodies in consequence of their feeble conducting powers the following method was had re- course to with perfect success :-The various substances examined were cut with the greatest care into cubes of 2.8 inches in the side and a hole drilled in the centre of one of the faces half way through large enough to receive the bulb of an exceedingly sensitive thermo- meter together with a little mercury to improve the contact with the substance of the cube.The temperature of the mass being exactly observed it was next plunged all but its upper surface into a large bath of mercury heated by steam whose temperature remained con- stant at 2 1lo,and the time of rise of the thermometer for every suc- cessive loo accurately noted until the maximum was reached thus affording a comparison of the relative conducting powers or perhaps more properly resistance to the passage of heat towards the centre of the mass.In the course of these experiments a very extraordinary circum- stance was observed ;although the greatest care was taken to equal-ize the temperature of the cubes by suffering them to remain at least twenty -four hours before experimenting in an uniform temperature 26 yet they never exactly acquired that of the room or even agreed among themselves in this respect ; an observation which led the au- thor to the suspicion that the genemlly received doctrine of an equal distribution of secsible heat among bodies in contact and not influ- enced by external sources of disturbance might not prove strictly true but that on the contrary each of a number of different sub- stances exposed under similar circumstances to the influence of a medium of uniform temperature acquires a proper temperature of its own.The same thing was observed with higher degrees of heat ; a mass of slate for example plunged beneath the surface of uniformly heated mercury and maintained there long after the thermometer in the slate had reached its maximum always exhibited a temperature decidedly below that of the surrounding metal. A third series of experiments were made with a view of ascer- taining the relative rates of cooling in air of the various materials examined from a higher temperature to that of the atmosphere. The arrangement consisted of the cubes before described covered externally with thin paper for the eake of uniformity of surface the same delicate thermometer being iuserted in the bole in the centre together with a little mercury for the sake of contact.The cubes were each in turn heated in the steam-chest used for the specific heat experiments until the included thermometer rose to 200° ; they were then removed suspended in the air and the time of fall of tem- perature for every 10 degrees carefully noted. The precautions required to be taken to avoid errors of different kinds were fully described and drawings of the apparatus used ex- hibited together with a most elaborate and complete set of tables embodying the whole of the results. March 15.-Itobert Porrett Esq. in the Chair.Joseph Redtenbacher M.D. Professor of Chemistry in the Uni- versity of Prague was elected a Foreign Member of the Society. Edward Schunck Esq. was elected a member. The following communications were then read :-Second Part of Mr. Hutchinson’s Paper. 39. ‘‘ On the Preparation of artificial Yeast,” by George Fownes Ph.D. (See Memoirs Vol. I. Art. 19.) March SO.-Anniversary Meeting the President in the Chair. The following Report of the Council was read by the President and subsequently ordered for publication. The occasion of the first Anniversary enables the Council to 27 refer to tlle atctisfactorp progress which has been made during the last year in establishing and organizing the Society. ‘l’he rapid imp\Tement and espansion of chemical science which distinguishes tile present time with the estension of its useful applications to physiology to agriculture and in so many other directions excited the originators of the Chemical Society to assist in the impulse which their favourite Ecience had received ; while the increasing public interest in chemical information and the consequent multi- plication of chemical inquirers led them to anticipate the support of a class of men sufficiently numerous to form the basis of a swiety which should insure to the chemists of this country the advantages of association and of mutual co-operation.The resnlt has not dis- appointed the anticipations of its projectors the Chemical Society already containing a body of members sufficiently numerous to insure it8 stability including nearly all the distinguished chemists of the country.The Societyeommenced on the 30th of March last with 77 mem-bers. Since that time 50 members have been elected making in all 127 members. Of these 11s are ordinary members ; 6 asso-ciates ; and 3 foreign members. In the selection of foreign mem- bers the Council has hitherto confined itself to the distinguished individuals who have directly assisted in forwarding the objects of the Society by contributing papers to be read at its meetings. The state of the funds of the Society is satisfactory and will be fully exhibited in the audited accounts of the Treasurer which are appended to this Report. l‘he Council has hitherto restricted the expenditure to the most necessary and useful objects of the Society namely the rent of its place of meeting and the publication and cir- culation of its Transactions.The Socicty first availed itself of the accommodations offered by the Society of Arts. These they were led to abandon from some anticipated inconveniences from restnc- tion to experimenting. Their present accommodations in the Western Literary and Scientific Institution are not orpensire but are liable to objections among which the want of a Council-room and of any place of deposit for the property of the Society are suffi-cient to prevent their being permanently retained. The Council is therefwe again making inquiry for suitable acconmoclations and will report the result to the Society before the Summer recess.‘l’he Society had published Two Parts of Proceedings and hlemoirs the first in June last upon the adjournment of the Society and the second recently in the beginning of February. It had received from the commencement to January the 18th the period included in these publications 33 communications all of them interesting and several of them of great value ; of which 14 are printed entire in the Memoirs and full abstracts given in the Proceedings of the remaining 19. The Council is fully sensible that the utility of the Society and its reputation in the scientific world will mainly depend upon its publications and presses upon mc‘ml)ers who have already contril)utcd the importance of continuing their support and invites similar assistancc from othcrs.‘1’11~hwt tllid* of tiic Society are 28 due to all the contributors to its Transactions more particularlv to those foreign chemists of great eminence who have lent their aid in this way and evinced a friendly interest in the establishment of the Society which is most gratefully acknowledged. The Society has received during the Session several presents of books and interesting specimens from different members with a do- nation of five guineas from Dr. Leeson for which thanks have been returned to the donors. The Council is convinced that donations both of books and specimens would rapidly increase provided a suitable place of deposit were provided for the property of the Society accessible to the members. In selecting a future place of meeting for the Society the possession of such accommodations will therefore be looked upon as an essential requisite.The Council has lately occupied itself with the preparation of a code of laws and regulations for the government of the Society founded upon the practice of other scientific bodies and the experience of last year. This undertaking has been completed and the rules proposed will be brought under review of the Society at the present general meeting. A. AIKIN, Treasurer with the Chemical Society. Dr. .€ s. d. Subscriptions from 70resident members .. 140 0 0 Ditto from 36 non-resident ............. 36 0 0 1 composition ........................ 10 0 0 1 donation. .......................... 5 5 0 6191 5 0 -~ Cr.By printing and engraving.. ............ 7 8 8 -stationery ........................ 7 15 3 -postage and parcels. ................ 3 9 10 -rent ............................... 21 5 0 39 18 9 By balance in the Treasurer’s hands ...... 151 6 3 El91 5 0 Auditor’s Report. I have examined the accounts of the Chemical Society of London presented by Arthur Aikin Esq. as Treasurer and find the monies received to amount to the sum of A185 5s. Od. and the expenditure (for which vouchers have been shown) to amount to the sum of &37 8s. .Id. leaving a balance in the hands of the Treasurer of 6146 16s. 8d. P. N. JOHNSON. London hlarch 11 1842. 29 The following gentlemen were elected as Officers and Council for the ensuing year :-President.-Thos.Graham Esq. Vice-Presidents.-William Thos. Brande Esq. ; John Thos. Cooper Esq. ; Michael Faraday Esq. D.C.L. ; Richard Phillips Esq. Treasurer.-Arthur Aikin Esq. Secretaries.-Robert Warington and George Fownes. Foreign Secretary.-E. F. Teschemacher. Council.-Dr. Thos. Clark ; Dr. Chas. Daubeny ; ,John Fred. Daniell Esq. ; Thos. Everitt Esq. ; W. R. Grove Esq. ; James F. W. Johnston Esq.; Percival N. Johnson Esq.; George Lowe Esq. ; William H. Miller Esq. ; Robert Porrett Esq. ; Dr. G. 0. Rees ; Lieut.-Colonel Philip Yorke. The laws of the Society as drawn up by the Council were sub- mitted to the meeting. and having been read and discussed were confirmed with amendments and ordered to be printed for the use of the members.The thanks of the Society were given to the Officers and Council for their exertions during the past year. April 5.-The President in the Chair. Specimens of &I.Claudet's improvedDaguerreotyped portraits were laid on the table. Mr. W. J. Cock presented to the Society a specimen of native chloride of silver from Mexico. " A Letter to Lord Aberdeen on the state of the Schools of Chea mistry in the United Kingdom," by Wm. Gregory M.D. was pre- sented by the author. " What can be done for English Agriculture," a letter addressed to the Nlarquis of Northampton by James F. W. Johnston MA. &c. was presented by the author. The following communications were then read :-40. Extract from a letter from Wm. H. Miller Eoq. Professor of Mineralogy in the University of Cambridge.'' I regret that my engagements in Cambridge have prevented my being present at the meeting of the Chemical Society especially as I was desirous of offering my services in- determiniog the form of any crystalline products that may present themselves to chemists who are engaged in original researches. Also in return I might make bold to ask some members of the Society to supply me with certain objects of crystallographic and optical research from their laborato- ries." 41. " On the Analysis of the Chalk of the Brighton Cliffs," by Dr. Edw. G. Schweitzer. 30 My attention was directed to the soil of this neighbourhood for the purpose of ascertaining if the chalk contains any ingredient pe- culiarly favourable to the growth of Gramines in consequence of the well-known fact that the herbage of the South Downs along the coast of Sussex affords a superior food for cattle producing meat of excellent quality for which these Downs are justly celebrated.The result of my analysis substantiates the presence of phosphate of lime an ingredient valuable for the nutrition of plants. The chalk is composed of the following substances in 100 parts :-Carbonate of lime ........ 98-57 ...... of magnesia .... 0.38 Phosphate of lime ........ 0.11 Protoxide of iron ........ 0.08 ...... of manganese.. .. 0.06 Alumina.. .............. 0.16 Silica.. ................ eG1 -100~00 To ascertain the quantity of phosphoric acid I followed Dr.Schulze’s method (Journal fur prakt. Chemie xxi. S. 387-389) which he recommends for the analytical investigation of soils. Finding it useful and correct I subjoin an extract from his treatise. The process is based upon the fact that phosphate of lime and phosphate of magnesia are soluble in acetic acid while the phos- phate of peroxide of iron and phosphate of alumina are not so This being the case the soil or mineral is to be treated with hpdro- chloric acid and the iron which the solution contains per-oxidised the phosphate of protoxide of iron being soluble in acetic acid. Should the muriatic solution contain more phosphoric acid than oxideof iron or alumina (which seldom is the case as the latter are usually predominant,) peroxide of iron or alumina is to be added the solution must also be freed from every trace of silica.The earthy murintes are precipitated with ammonia after which acetic acid is added and the whole gently digested. The precipitate will dissolve again with the exception of the phosphates of peroxide of iron and alumina. When both these ingredients enter into the pre- cipitate caustic potassa will give the means of ascertaining their respective quantities. The solubility of the phosphate of protoxide of iron and the inso- lubility of the phosphate of peroxide of iron in acetic acid when freshly precipitated give an excellent method to separate quantita- tively these two degrees of oxidation. The manipulation is obvious. The discovery by Professor Ehrenberg that the Brighton chalk consists of microscopic shells is a decided proof of its animal origin to which may now be added an additional one viz.the presence of phosphate of lime which is a usual although secondary ingredient of the shells of Crustacea. 42. ‘‘ On the Action of Chromate of Potash on the Protosulphate of Manganese,” by Robert Warington Esq. Jn the course of some experiments on tlic formation of double salts of chrcjniic acid with various bases depending on the teiidency which might arise from the resulting aflinities to the formation of certain crystallized combinations the subject of the present brief comniunication came under my notice. On adding a solution of the yellow chromate of potash to one of the protosulphate of manganese no turbidity or precipitate takes place but the mixed fluids become of a deep orange red colour and after a short period the surface is covered with a dark brown crust or film and the whole of the containing vessel is coated with the same substance ; at times when the solutions are dilute this deposit assumes a crystalline appearance.If this compound is prepared under the microscope in the manner described in a former paper the first effect is the appearance of numeroils minute spherical gra- nules of a fine crimson hrown colour which gradually increase in size until about from six to seven 250th~ or *025 of an inch in dia- meter ; a number of delicate crystallized spicuk are then observed to start out in radii from their sides ; and when the solutions em- ployed for its production are diluted fine stellated groups of pris- matic crystals are obtained.When this substance which has a dark chocolate hue is examined by a strong transmitted light it has a rich crimson brown colour it possesses the following proper- ties .-it is soluble in diluted iiitric or sulphuric acids without residue yielding an orange-coloured solution ; when acted upon by hydrochloric acid chlorine is evolved and a brown fluid results which by the addition of a few drops of alcohol or other deoxidizing agent becomes of a fine emerald green. The following analysis was made of it :-8*2 grains previously dried at a temperature of boiling water were submitted to a long-continued red heat in a small green glass tube to which a chloride of calcium tube was attached ; it lost 1.0 grain which corresponded with the weight gained by the absorption tube ; 8.2 grains dissolved in dilute nitric acid and pre- cipitated while boiling by caustic potash gave after the necessary treatment 4.5 grains of the red oxide of manganese ; the solution was then acidified by sulphuric acid and evaporated to dryness to expel the nitric acid redissolved deoxidized by alcohol and the oxide of chromium thrown down by ammonia again evaporated to dryness to avoid the possibility of any of the oxide being in solu-tion and the oxide of chromium well washed gate 2.3 gains.Wc have therefore 4.5 grains red oxide manganese. . = 4.185 protoxide 2.3 ... protoside chromium .. = 3.000 chromic acid 1-0 ...water . . . ... . .... . . 1-000water -8.188 By calculation this should be . . 4.141 protoxide 3.014 chromic acid 1.043 water Or 1 atom chromic acid + 2 atoms protoxide of manganese + 2 atoms water. Represented by Cr 0 + 2 Mil 0. $-2 H. 0 Chern. I-’roc.-No. III. 32 April 19.-Wm. Thos. Brande Esq. Vice-president in the Chair. Mr. Collen exhibited specimens of his calotyped portraits. Mr. H Croft exhibited and described Dr. Bunsen’s new galvanic arrangement. Alfred Baring Garrod Esq. was elected an Associate. The following communications were then read :-43. “ On the Equilibrium of the Temperature of Bodies in con- tact,” by E. A. Parnell Esq. In reference to observations recently made by Mr. Hutchinson on the difficulty of raising the temperature of any substance to the de- gree of the medium by which the heat is applied Mr.Parnell ob- serves “From what I know of the mode in which Mr. Hutchinson operated it is probable that a loss of heat occurred by radiation from the substance operated on ; by radiation first to the cover of the bath and from this to external objects. On adopting precautions to avoid this source of error I found that in a steam-bath the tem- peratures attained by substances were 1. Olive oil. ..... degree below the temperature of the steam. ... ... ... 2. Water.. ...... i!3 And in a water-bath,- 3. Water ....... + degree below the temperature of the water. 4. Vapourof &her 1 ... ... ... 5. Air.. ........ 1 ...... ... In the two first experiments the apparatus used was a large flask closed with a cork having several perforations through one of which was admitted a wide tube containing the liquid operated on the tube not dipping so far as the surface of the water in the flask which was kept boiling. In the remaining three a copper water-bath was employed the water vapour or air being contained in a glass globe of about fif-teen cubic inches capacity having a narrow neck through which the thermometer was admitted. The globe was supported in the bath by a wire-cage in the same manner as is done in the operation of taking the density of vapours. It would hence appear from the proximity of the temperature of the substance heated and the bath that if the experiments were con- tinued a sufficient length of time and every chance of error avoided the substance might be heated to an equal degree and the law of equilibrium of temperature maintain its universality.I could never however raise the temperature of sther vapour nearer than one degree below the temperature of the bath and to effect this required at least half an hour. I would therefore recom- mend in taking the density of vapours that the temperature of the globe be considered as one degree less than that of the bath in making the calculations. Notwithstanding with this correction the weight of the vapour can scarcely be effected to a greater extent than 804 grain. 33 44. ‘‘ On the Preparation of Hippuric Acid,” by Geo. Fownes Esq.Being very desirous of possessing a specimen of a very interesting substance hippuric acid namely and failing to obtain it in any quantity from the horse-urine collected in London stables I was induced to make trial of that of cows and speedily found it to be a substance highly advantageous for the purpose. Perfectly fresh cow-urine presents the aspect of a transparent amber-coloured liquid of peculiar but not disagreeable odour and quite neutral to test-paper. When this is evaporated down in a water-bath to about one-tenth and mixed with hydrochloric acid n very large quantity of a brown crystalline substance separates which is hippuric acid. It is very easy in this way to operate upon whole gallons of the liquid and thus procure many ounces of hip- puric acid.To purify this substance I find the following method very ad- vantageous. The brown rough acid is dissolved in boiling water of which by the way it requires a much larger quantity than from the descriptions given would be imagined and through the solution a stream of chlorine gas is transmitted until the odour of that gas becomes perceptible in the liquid and its brown colour passes into a sort of deep amber-yellow. The hot solution is then filtered through cloth and upon cooling the acid still very impure crystal- lizes out. The acid is next dissolved in a dilute hot solution of carbonate of soda taking care to have a little excess of the alkali digested for a few minutes with a little animal charcoal filtered and lastly the solution strongly acidified by hydrochloric acid which removes the base and sets free the hippuric acid.Should that substance not be by such treatment rendered perfectly white it may be again dissolved in hot water a little chlorine passed the solution supersaturated with carbonate of soda digested with animal charcoal and once more decomposed by an acid. . It is to be observed that hippuric acid only crystallizes in a distinct and characteristic manner when pure or at least when in a condition approaching that state ; under other circumstances it usually separates either as short radiated needles or as a granular crystalline powder. The latter happens when soluble salt is present. If the urine instea2 of being quite fresh is at all ammoniacal then during the evaporation a very large quantity of ammonia is disengaged accompanied by slow effervescence and the liquid affords as Liebig has already pointed out benzoic acid only with- out a trace of hippuric.The great density of the urine of the cow is a remarkable circum- stance ; one sample affording much hippuric acid gave the sp. gr. of 1.0325,which is considerably higher than that of human urine. This density is chiefly due to a most prodigious quantity of urea which is easily extracted from the brown liquid remaining after the separation of the hippuric acid by the aid of il hot strong solution of 34 oxalic acid which throws down the slightly soluble oxalate. This can bc decomposed by chalk and the urea extracted without having recourse to alcohol.Besides these two substances hippuric acid or rather hippurate of an alkali and urea cow-urine contains a little uric acid phosphates and other salts in tolerable abundance. The constant occurrence of so much urea in the urine of all ani- mals both granivorous and flesh-eating tends greatly to strengthen the opinion that it is by this channel almost alone that the removal of those portions of the azotized constituents of the body which have been worn out as it were or in the act of undergoing decay is effected. It is well known that such substances by ordinary putre- faction furnish carbonate of ammonia ;but in the body this process seems to have been modified in such a manner that in place of that substance urea or carbamide is generated which is destitute of the irritating power upon the orgms which a corresponding quantity of the ammoniacal salt would possess.It has been suggested that hippuric acid is not a direct product of the animal system but is formed by the union of benzoic acid or its elements with those of lactate of urea the benzoic acid being present in the food and the recent experiments of Mr. Garrod cer- tainly countenance the opinion. But these attempts to detect ben- zoic acid in the food of these animals were in the hands of Liebig quite unsuccessful and it seems unlikely that it would be found at any rate in considerable quantity in such substances as grains and mangel-wurzel which with the addition of a little hay consti- tuted the food of the cows from which such an abundant supply of hippuric acid was obtained.There is only one other point which requires notice and that is the nature of the change which hippuric acid so readily undergoes by putrefaction. It is astonishing that a substance which so pow-erfully resists the action of chlorine should be so easily affected by simple contact with piitrefying matter. A glance at the composition of hippuric acid will show that this change is altogether different from that which urea sufTers under similar circumstances the assimilation namely of the elements of water by which it becomes carbonate of ammonia. Hippuric acid on the coiitrary seems to pass into benzoic by an absorption of oxygen from the air carbonic acid and ammonia being at the same time produced.Hippuric acid.. . . C, H N 0, Subtract-Benzoic acid ... . . C, H 0 which by addition of 6 cq. of oxygen from the air would furnish I cq. ammonia and 4 rq. carbonic acid. 35 May 3.-John 'rhos. Cooper Esq. Vice-president in the Chair. Mr. Cooper Jun. exhibited specimens of photographic pictures taken by the process of Mr. Beard. The following communication was then made :-45. '' On a curious Formation of Prussian Blue," by Robert Porrett Esq. Mr. Porrett was led to attend to this subject by an observation accidentally made while walking in the garden of a frienq. He found that a great number of the pebbles in the gravel walk were tinged of a fine bright blue colour; and on remarking the appear- ance to the owner and inquiring as to the cause though it had never before attracted notice he ascertained that before the fresh gravel had been laid down the walks had been strewed with some refuse lime from the gas-works for the purpose of destroying the worms and over which the red gravel of the neighbourhood of London had been placed only a few weeks before the appearances described were observed.The blue colour was entirely confined to the upper surface of the pebbles which was exposed to the atmospheric air and was found to be Prussian blue. The pebbles affected were siliceous having a white exterior coating. Mr. Porrett considers this production of Prussian blue to have arisen from some of the gas-lime having been dropped accidentally on the surface of the new gravel and that the peroxide of iron there found had been deoxidized by some of the sulphur compounds contained in the gas-lime giving rise to the formation of a combination of iron with cyanogen also present in the lime and calcium and that this compound had been decomposed by the action of the carbonic acid of the atmosphere or by the siliceous matter of the stone and thus causing the formation of the Prussian blue.May 17.-Wm. Thos. Brande Esq. Vice-president in the Chair. Mr. U'arington exhibited preparations of the various forms of the chromates and bichromates of silver. Mr. Porrett presented to the Society a number of the pebbles tinged with Prussian blue described at the previous meeting. Dr. Clark presented to the Society an improved ps-burner for a laboratory table.Dr. Edw. G. Schweitzer William Bacon Esq. and Mr. John Turner were elected members of the Society. The following communications were then read :-46. Extract from a letter froin Professor Clark. 'a The burner is to bc fixed into a table by screwing thereto the cir- 36 cular projectionff. There are two stop-cocks. The horizontal one g is for admitting the supply of gas which passes up the fixed tubepp into the sliding tube m m. Between the outer fixed tube t t and the inner fixed tube pp,water is contained to serve as a lute to m\ confine the gas. The sliding tube is kept at whatever height it may be placed by means of a spring inserted in a stuffing-box formed by the screw ss aboveff.The spring is represented apart r. It is formed out of a short bit of another metallic tube of such bore as a only to permit the tube rn m to slide through it easily. Four holes in the circle of the wider tube r are bored$ at equal distances and a vertical slit is cut by a saw . from each hole through to the bottom of the tube. After being thus cut the cut parts are squeezed to- gether by the hand and the tube r being put over the tube m and confined in the stuffing-box at s,forms ir convenient spring for keeping the sliding tube m at whatever height it may be placed. The stop-cock w is to let out any water that may by accident get into the tube pp. The tube m m should not be less than half an inch in diameter. The burner b which is copied after one in Professor Graham’s laboratory Uni- versity College burns after the manner of a rose-burner but it is in the form of a ring instead of being solid.It may be called a ring-burner. It per- mits a much more free access of air especially when the flame is placed very close to a vessel. This burner also supplies gas very advantageously for mixture with air in a cylinder at the top of which the mixture burns over wire gauze. The sliding tube relieves the operator from all-cumbrous supports to his burner or from the necessity of having moveable supports to the vessels to be heated. A ring supported by three lem. the whnle made nf tinned irnn. affnrds a chean. -I--3-,_--..-------__---,-------rp stable and convenient support tQ vessels although of considerable weight.” 47.rr On some Salts of Cadmium,” by Henry Croft Esq. (See Memoirs Art. 20. Vol. I.) 6 48. ‘I An Examination of two specimens of South Sea Guano imported for agricultural use,” by George Fownes Esq. No 1.-Presented tho aspect of a pale-brown soft powder with a few lumps having in their inside whitish specks ; its odour was exceedingly offensive. Treated with hot water and filtered it gave a yellow feebly alka- line solution not rendered turbid to any extent by the addition of acid which contained much ammoniacal salt some sulphate and chloride a very large quantity of oxalate and both potash and soda the latter most abundant. 37 The undissolved substance appeared to be a mixture of uric acid earthy phosphates and brown organic matter.Fifty grains of guano by incineration in a platinum vessel left 16.9 grs. fine greyish white-ash. This ash treated with hot water and the whole placed on a filter left a quantity of insoluble matter weighing after being well Washed dried and ignited 14.6 grs. this was almost entirely soluble in warm dilute hydrochloric acid precipitated by the addition of ammonia and evidently consisted of phosphates of lime and magnesia. The aqueous solution was slightly alkaline contained much chlo- ride some sulphate a very notable quantity of soluble phosphate some potash and a good deal of soda. Hence the following approximate result :-Oxalate of ammonia with trace of carbonate undecomposed uric acid brown organic mat- 33.1 66.2 ter and water ........................} Earthy phosphates with very little sandy matter 14.6 29.2 Alkaline phosphate and chloride with little} 2.3 4,6 sulphate ............................50-100.0 No. 2.-Darker in colour and having but little smell. Examined as in preceding case ; it contained no uric acid. Fifty grains gave- Oxalate of ammonia with little carbonate or-} 22a3 44.6 ganic matter and water ................ Earthy phosphates with little gritty matter. . 20.6 41.2 Alkaline sulphates chlorides and phosphates (both potash and soda the latter most abun- 7.1 14.2 dant). ............................... - 1-50-100' The last specimen is evidently older and in a more advanced state of decomposition than the other ; its odour is far less powerful and offensive ; it contains little or no uric acid but a larger proportion of inorganic substances.It is difficult to imagine a manure better fitted for almost uni- versal use than this ''guano ;" it contains in a highly concentrated form everything that plants require for their sustenance with the exception perhaps of potash which however is often abundantly supplied by a soil poor in other respects. The presence of a large quantity of oxalate of ammonia is a cu-rious fact and was early noticed ; there can be no doubt that this substance owes its existence in some way or other to the uric acid contained in the excrement of the sea-birds to the decomposition of which the guano-deposits are due.We can easily imagine that in this mass of putrefying substance kept in a moistened state by the dews of night a decomposition of a peculiar kind may be set up in the uric acid and its gradual conversion into new products among which may easily be oxalate of ammonia effected perhaps somewhat after the following fashion :- Uric acid.. ......C H N90 2 eq. oxal. acid C4 4 eq. water ...... H o,} =(2 .. ammonia H,N 0 1 eq. oxyg. from air 0 1 . . cub. acid C 0 H6 N 0 c5HI3 N 0, c5 This view it must be remembered is merely hypothetical yet is borne out by the facts. The only case in which oxalic acid is known to arise from uric acid is in the artificial farmation of allantoin discovered by Liebig and in which uric acid water and peroxide of lead being boiled together give rise to oxalate of the protoxide of lead allantoin and urea; it is in short an oxidizing action so far resembling the one imagined but more complex.Uric acid (doubled) C, H N 0 Allantoin.. ..C H N 0 3 eq. water. ..... H oJ}={Urea .......C H,N,O 2. .ox. from perox. 0 2 eq.oxa1. acid C p-CI,H,N,O, C,,H,N,O, It is very unlikely that this peculiar mode of decomposition should occur under the circumstances in which the guano is pro-duced ; urea certainly would not resist destruction a week and no doubt the allantoin would share the same fate. It was thought worth while nevertheless to examine one of the specimens (No. 1) carefully for these two bodies a portion of the substance being acted upon by hot water and the filtered solution cautiously evaporated to a small bulk whereupon crystals were abundantly formed on cooling.These being dissolved in hot water decolorized with animal charcoal and the solution once more con- centrated a second crop was got but slightly coloured. These however turned out on examination to be nothing but oxalate of ammonia. The search for urea was equally unsuccessful. There is a curious relationship between the three bodies oxalate of ammonia oxamide and allantoin the only difference in compo- sition being the diminishing proportion of the elements of water. Anhydrous oxdate of ammonia (doubled) .. C H6 N 0 Oxamide (doubled) .................... C H,N,O Allantoin ........................... C H N 0 49. “On the production of Artificial Uranite,” by W.J.Cock Esq. The subject of the present communication was observed during the preparation of the oxide of uranium from its mineral Pitchblende ; it was obtained as follows :-The mineral was pulverized and well calcined; it was then di-gested with diluted nitric acid which dissolved the greater part of the soluble contents. (From this solution none of the precipitate was obtained.) The undissolved residuum was washed and dried and again cal- cined. It was digested in nitric acid rather stronger than before. and gave a solution of a darker green than the first. This solution was left several weeks in open vessels. and upon its being drawn off 39 a quantity uf the grwn prccil)itate was found adhering to the bottom and sitles of the Y.CJSSC:~$.‘L’lie composition which is veryv;viable,of the mineral Pitchblende as given by Kerthier in his Trait; des Essnis pm-Icc voie sechc from two analyses is in the 100 parts,-. Protoside of uranium ............ 51.6 G0.O Carbonate of magnesia. ........... Peroxide of iron ................ 3.3 7.2 2-5 Alumina (clay). ................. Sulphuret of iron and copper ...... Arsenical pyrites (iron) .......... Sulphuret of lead.. .............. 17.2 5.8 6.0 1.2 9.05.5 9.9 3.5 Sulphuret of zinc. ............... Carbonate of lime. ............... 2.2 1.4 2.2 Water and bitumen ............. 4.2 5.2 98.7 95.5 No mention is here made of the phosphoric acid which enters into the composition of the artificial uranite.The composition of the nn- tive urnnite as also of the double phosphate of uranium and copper (chalkolite) are thus given by Rerzelius :-Uranite. Chalkolite. Oxide of uranium ............ 59-37 60.25 Lime.. ..................... 5.65 Oxide of copper .............. s.44 Barytes ................... 1*.51 Magnesia and oxide of manganese * 19 Phosphoric acid .............. 14.63 15.56 Water. ..................... 14.90 15.05 Gangue .................... 2.55 -70 Fluoric acid and oxide of tin .... trace _I_ 99.10 100-It appcars that these two minerals are found mixed together in all proportions and from the artificial compound which forms the sub. ject of the present notice containing both oxide of copper and lime that it is also n mixture of these salts.The following Analysis of the *‘ Artificial Uranite,” inade under the superintendence of Mr. Parnell u7as read as an appendix to the above :-Phosphate of uranium .............. 33. Oxide of copper .................... 19.5 Lime ............................ 1.8 Water.. .......................... 21.5 Phosphoric acid in combination with 8.2 oxidc of copper anti lime (loss) .... ~ 1 1 oo*oo The process of analysis was the following :-(1.) Having previously ascertained by a qualitative analysis that the sole constituents of the sul)stance arc phosphoric acid peroxide Chem. Pror.-No. 111. 40 of uranium oxide of copper lime and water a known weight was dissolved in hydrochloric acid and copper was precipitated as sul-phuret by transmitting sulphuretted hydrogen gas through the solu- tion.The precipitated sulphuret when filtered and washed was digested in nitric acid and from the solution thus obtained oxide of copper was precipitated by potash washed ignited and weighed. (2.) The solution separated by filrration from the sulphuret of copper was next evaporated to dryness and mixed with a little con- centrated sulphuric acid to convert phosphate of lime into sulphate the mixture was diluted with alcohol in which sulphate of lime is quite insoluble and filtered. The sulphate of lime was washed with alcohol dried ignited and weighed. (3.) The filtered alcoholic solution containing phosphate of ura-nium dissolved-in the excess of sulphuric acid was evaporated to dryness the residue digested in nitric acid and phosphate of ura-nium precipitated from the acid solution by ammonia.This when washed and dried was gently ignited and weighed. (4.) The water contained in the substance was determined by ob- serving what loss in weight it sustained when calcined at a dull red heat; and (5.) The remaining ingredient the phosphoric acid in comhina- tion with oxide of copper and lime was considered as the deficiency on the weight of the original substance. 50. ‘‘Some additional Observations on the Red Oxalate of Chro-mium and Potash,” by Robert Warington Esq. (See Memoirs Art. 17 Vol. I.) 41 November 1 1842.-The President in the Chair. “ A Treatise on Crystallography,” by W~lliam Hallows Miller F.R.S.Professor of Mineralogy in ft. John s College Cambridge was presented by the author. “ On the Heat developed during the Combination of Acids and Bases,” by Thomas Andrews M.D. from the author. “Experimental Inquiries regarding Gravitation,” by James Scrym- gour Esq. from the author. “ Objections to Mr. Redfield’s Theory of Storms,” by Dr. Hare and “A Letter to William Whewell M.A.,” by Or. Hare from the author. A number of copies of these two papers was presented by the author for distribution among the members of the Society. ‘6 No. 1. of the Chemical Gazette,” by Messrs. W. Francis and Henry Croft from the editors. “ A Word or Two on Guano,’’ by W. H. Potter from the author. “ Is Selenium a true Element ?” by S. Pieese from the author.Mr. Warington presented part of a cast-iron grating which had been subjected to the occasional action of slightly acid liquids for several years and which exhibited the partial removal of the metal while the residual graphite retained the original form. Charles D’Epinay Esq. William Francis Esq. and E. A. Pmell Esq. were elected Members of this Society and Mr. Matthew Red- mond an Associate. William Thomas Brande Esq. F.R.S. Vice-president having taken the Chair the following communications were then read :-51. “ On Heat of Combinations,” Part I. by ‘Thomas Graham. Esq. F.R.S. (See Memoirs Art. 21. Vol. I.) 52. “ On Pyrogallic Acid,” by John Stenhouse Ph.D. (See Memoirs Art. 22. Vol. I.) 53. ‘‘ On the Analysis of Organic Substances containing Nitro- gen,” by George Fownes Ph.D.The circumstance which led to the present note on the analysis of azotized organic bodies was an attack lately made by M. Reiset on the new method of determining the nitrogen in such cnsee,put into practice with great apparent success by MM. Will and Varren- trapp of Giessen. After drawing a favourable contrast hetween the new method and those previously in use when the propcution of nitrogen to be determined is small the author proceeds to inquire into the validity of the objections before alluded to. It is stated by M. Reieet that when sugar is burned with the usual mixture of hydrate of soda and lime in fine powder and the gases evolved conducted into hydro-chloric acid an addition of pure chloride of platinum and evapora- tion to dryness gives rise to a quantity of the double chloride of platinum and ammonium indicating in some experiments 1 to 1.5 per cent.of nitrogen in the body analysed ;and as this was considered too great to be attributed to accidental impurity it was ascribed to the absorption of the nitrogen of the air contained in the tube by Chern. Proc.-No. 11‘. the mixture of carbonaceous matter and alkali and the subacquent conversion of the cyanide so formed into ammcnia ; and this idea was strengthened by repeating the experiment with the tube filled with hydrogen instead of air when the production of ammonia was found to be lessened. It became important to know how this very serious objection could be disposed of.On repeating the experiment it was found that when the finest white sugar-candy was thus burned a certain quantity of the yellow platinum salt always remained upon the filter after washing with the mixtui-e of alcohol and ather but this quantity instead of indicating 1 per cent. or more of nitrogen in the sugar gave in three exye- rinients only -06per cent. a quantity attributable to impurity. Tartaric acid. and charcoal made from white sugar gave similar results the ammonia amounting to a mere trace doubtless due to foreign admixture. It is difficult from such experiments to avoid drawing the con-clusion that the appearance of the nitrogen is in all such cases due to accidental impurity in the body hurned and not to any direct or indirect formation of ammonia from the nitrogen of the air.To those practising the new method under discussion the fol-lowing observation may be useful :-in mixing the organic matter with the alkali in a smooth porcelain mortar some inconvenience is experienced in the obstinate adhesion of some of the mixture to the hottoin of the mortar and also to the pestle and which is often with difficulty remorcd by triturating two or three small successive por- tions of dry soda-mixture ;the powder is too soft to cleanse perfectly the mortar and a little left behind would necessarily occasion loss in the ultimate result. By the use of a few grains of finely powdered glass this inconvenience is obviated ; the glass is rubbed for a few seconds in the mortar which it cleanses in the most complete man- ner and can then be transferred to the rest of the mixture in the tube where its presence can occasion no injury whatever.As additional testimony to the value of the new method Dr. Fownes subjoins the results of a sct of experiments made by himself with a view of testing the process before venturing to employ it upon bodies of yet unltnown composition :-Uric Aid. I. 2. 3". 4". Substance ................. 4-99 5-14 5.21 5-45 Platinum salt with filter. ..... 95-14 30.2 30.53 31.62 Filter .................... 3.13 3.29 3-28 3.12 26.01 26-91 27.25 2$-5 Nitrogen .............. 1*63OG 1.70'75 1.729 1.808 PCTcent. .............. 33.08 33.22 33.19 33-19 'l'heorc tical per- centage. ......... 3;3*3G Mixed with 4 grains of sugar.43 Urea with a little sugar. Substance ........................ 4.17 Platinum salt with filter ............ 34. Filter ........................... 3-35-30.65 Nitrogen ........................ 1.945 Percent. ........................ 16-64 Theoretical quantity.. .... 46.78 Hippuric Acid. 1. 2. Substance ............ 8.85 8.24 Platinum salt and filter .. 14.17 13.43 Filter ................ 3.44-10.73 3.23-1 0.2 Nitrogen ............. -6809 *64729 Per cent. .............. 7.7 7.85 By theory ............ 7.82 Allantoin with a little’bugar. 1. 2. I Substance. ............. 8-23 5.47 Platinum salt .......... 45.61 30.47 Per-centage of nitrogen .. 35.17 3503.5 Theoretical quantity...... 35.5 November 15 .-The President in the Chair. ‘‘Elements of Chemical Analysis,” by E. A. Parnell Esq. pre-sented by the author. ‘‘ Taylor’s Calendar of the Meetings of the Scientific Bodies of London for 1842-43,’’ from the editor. A Specimen of sublimed arsenious acid in crystals was presented by Mr. Robert U’arington. Dr. Andrew Fpfe was elected ZL Member of the Society. r, I he following communications were read :-54. “ On some Astringent Substances as Sources of Pyrogallic Acid,” by John Stenhouse P1i.D. (See Memoirs Art. 23. J’ol. I.) 55. “ On some new Cases of Galranic Action and on the Con- struction of a Battery without the use of oxidizable Xfetds,” by Alex-ander It. Arrott Esq. (See Memoirs Art. 24 1‘01. 1.) Decemim-6.-’i’lie President in the Chair Nurnerous specimens of rnrc chcmicul products were exliibi ted by Mr.Lovd Nullocl;. 44 The President exhibited a stereotyped plate which had undergone a secondary crystallization By exposure to a damp atmosphere in contact with paper. “ The Chemical Gazette ” as continued was presented by the editors. “ Sur l’huile essentieUe de Bouleau,” par M. A. Sobrero presented by Thomas George Tilley Esq. The following communications were read :-56. Extract from a letter from Dr. Will dated Giessen November 10 1842. “I have repeated Reiset’a experiments on the combustion of sub- stances free from nitrogen with caustic soda and lime. The result is that his statements are incorrect. There is not a trace of am-monia formed if the alkaline mixture as well as the employed sub- stances is quite pure so that Reiset’s observations are not at all an objection to our method for determining nitrogen.I believe Keiset’s alkaline mixture contained nitre or something else othervise he could not have obtained such results. ‘< From my experiments I was led also to repeat Faraday’s in- vestigations on the formation of ammonia and believe I shall find the cause why he sometides obtained ammonia and sometimes not by heating non-nitrogenous organic substances or zinc with hydrate of potash.” 57. ‘‘On fithogen and the Bthonides,” by William H. Balmain Esq. (See Memoirs Art. 25. Vol. I.) 58. ‘‘Report of some Experiments with Saline Manures contain- ing Nitrogen conducted on the Manor Farm Havering-atte-Bower Essex,” by M.W. F. Chatterly Esq. (See Memoirs Art. 26,Vol. I.) December 20.-Wm. Thos. Brande Esq. F.R.S. Vice-president in the Chair. The following gentlemen were elected Members :-Robert Howard Esq. ;John F. Macfarlane Esq. ;Loyd Bullock Esq. ; and Mr.l.5’. H. Balmain as an Associate. The following commuhications were read :-59. On the Division by Three of the Equivalents of the Phosphorus Family of Elements,” by Thomas Graham Esq. F.R.S. (See Me-moirs Art. 21. Vol. I.) 60. “Remarks on the Determination of Nitrogen in Organic Ana- lysis,” by W. Francis Esq. The presence of nitrogen in picrotoxine having been denied by all experimenters the author was induced to repeat with great care the analysis of that substance in the course of which researches abundant evidence of nitrogen ~‘~1s obtained.A few grains of pure picrotoxine heated in a tube with a iittle of the mixture of lime and hydrate of soda give off vapours which quickly restored the blue colour to reddened litmus paper ; the smell of ammonia was also quite distinct. 45 An analysis being made by the method of Messrs. Will and Var-rentrapp in order to determine the amount of nitrogen distinct yel- low crystals of the double chloride of platinum and ammonium were obtained corresponding in one experiment to 1.3 per cent. of nitro-gen and in a second to 0.7.5 per cent. Burned with oxide of copper numbers representing the carbon and hydrogen came out closely corresponding to the results obtained by Regnault.The observations of hl. Reiset in a late Nuniber of the ‘ Annales cie Chim. et de Phys.,’ threw sbme doubts upoii the value of the ana- lytical method above mentioned and the author was led in conse- quence to repeat the experiment on a specimen of. carefully purified sugar 1.649 sugar gave 0.048 of a brownish black substance on the filter wlhh calculated as the salt of ammonio-chloride of platinum gives 0.24per cerit. of nitrogen ; on being burnt it left 0.035 which calculated as metallic platina = 0.30 per cent. nitrogen; ‘2.130 sugar gave 0.053 of the black substance and when burnt 0.31 of platina affording in the one case 0.13 iii the other 0.20 per cent. as nitro-gen. ’The sugar to ensure purity had been crystallized twice out of an aqueous solution again dissolved and thrown down by alcohol collected and recrystallized out of water.A small quantity of it heated with some of the alkaline mixture in a test-tube afforded vapours which did not effect the red colour of litmus paper. Fre.. quently in analyses by this method especially when the organic substance is very rich in carbon fluid carburetted hydrogens distil over which remain behind on evaporation forming a black residue. This is not n.holly dissolved on edulcorsting4mith Fether and alcohol and goes to increase the weight of platinum salt if there be any. Tlie residue reinailling on tlie filter after edulcoration 11ith alcohol and =they in the second experiment did not exhibit under the microscope the least trace of the yeiloiv crystalline silt but IVRS of a blackish brown aniorphous apl:earmce.It iqqm~rs,therefore that the sub- stnnce calculntcd djove as aiiinionio-chloride of platinum was most probably platinum ~vhiciiIind becw reduced by these carburetted li!-clrogeus during evaporation. An analysis of osnniitlc by the new process gave an excellent result the per-centage of nitrogen falling jut below the theoretical quantity. 61. “ On the Sugar of the Eucalyptus,” by James F.IY.Jolin-ston Eq. F.K.S. (See Memoirs Art. 2i Vol. I.) G2. “ On tlie probable existence of Xitrogen conibiiied with Sili- con iii Soils and other Substances,” by IT. H. Ealmain Eeq. The stability of the compounds of boroii and silicon 11 ith nitrogen aiid the facility with wliich such compounds are produced when or-canic mntter is stroiigly lieated with a horate or silicatc seemed to render it probable tlint such bodies might occasionally exist in un- expected circumstances its in soils or ixiiicr‘tk for csttinplc and es-perinients wrc inadc with a view of directly wxrtaiiiing u-hether this uxs the ~ 2 1 ~ .of SCY~~I.~~~ Sainl~lc~ vdi icties ot soil were boil2cl tot’ w);iich tinit>~vitli 46 a mixture of dilute sulphuric and nitric acids then washed and dried and subjected to the action of hydrate of potash at a high tempera- ture ; ammonia was in all cases abundantly disengaged even after the purified soil had been heated to redness. In one instance the sample of soil was boiled with strong nitric acid as long as nitrous acid vapours were generated then submitted to the action of di-lute sulphuric acid washed again boiled with strong solution of caustic potash washed and then agitated with chlorine gas ; yet on being heated with hydrate of potash it gave off ammonia abundantly.It was inferred by the author that the nitrogen ultimately found was in combination with silicon and in that condition had resisted the action of the various agents employed for its removal. January 3 1813.-The President in the Chair Mr. John Turner presented a specimen of anhydrous sulphuric acid for the Society’s Museum and Mr. Robert Warington speci- mens of iodide of potassium and the double tartrate of potash and soda in fine crystals.R. H. Brett Ph.D. William Tudor Esq. and Charles Glassford Esq. were elected Members ; and Messrv. Alexander R. Arrott John Thomas Way and Septimus Piesse Associates The following communications were read :-63. “ On Palladium its Extraction and Alloys,” by W. J. Cock Esq. (See Memoirs Art. 28. Vol. I.) 64. ‘‘ On the Formation of Fat in the Animal Body,” by Justus Liebig M.D. (See Memoirs Art. 29. Vol. I.) January 10.-The President in the Chair. Agricultural Chemistry,” Part First by Thomas George Tilley was presented by the author. John Furze Esq. John W. Nyren Esq. and W. L. Metcalfe Esq. were elected Members. The following communication was read :-65. ‘‘ On the Formation of Milk in the Animal Economy,” by Lyon Playfair Ph.D. (See Memoirs Art.30. Vol. I.) February ’I.-Arthur Aikin Esq. Treasurer in the Chair. ‘‘Proceedings of the Glasgow Philosophical Society for 1841 and 1842,’y from the Society ; and two pamphlets ‘* On the Voltaic Cur- rent add Force,” by Alfred Smee were presented by the author with copies for distribution among the Members. . The following gentlemen were elected Members :-John Forster Esq. Edward €tea Esq. Paul De laRue Esq. and Isham Baggs Esq. The following communications were read :-66. " On a new Method of obtaining pure Silver in the hletallic Spate or in the Form of Oxide," by WilliamGregory M.D. F.R.S.E. (See Memoirs Art. 31. Vol. 1.) 67. '' Some Experimental Observations on the formation of Prus-sian Blue upon the surface of Gravel through the medium of Ferro- cyanide of Calcium." By Robert Warington.In a communication formerly made to the Society by Mr. Porrett on the above subject" that gentleman considered the production of prussian blue to have arisen from some of the gas-lime employed to destroy the wornis &c. arid placed under the fresh gravel having been accidentally dropped on the surface and that the peroxide of iron contained in the gravel had been deoxidized by some of the sulphur compounds of the gas-lime giving rise to the formation of a combination of iron with cyanogen and calcium and that this compound had been decomposed by the action of the carbonic acid of the atmosphere or by the siliceous matter of the stone thus causing the formation of prussian blue.An artificial ferrocyanide of calcium was formed by mixing hydrate of lime and prussian blue to the consistence of a cream ; and this was placed in an open part of a garden and numerous white-coated siliceous pebbles selected from the red gravel of the neighbourhood of London then partly immersed in the mixture so that the upper surfaces might be ex-posed to the action of the atmosphere and moisture ; in a few days the sides of the pebbles assumed the blue colour which gradually spread itself to the summits having the same bright tint as the pebbles presented to the Society by Mr. Porrett proving therefore that the ferrocyanide had been drawn to the surface either by that curious species of crystalline growth if the expression may be allowed which is exhibited by so many saline combinations during their crystallization or by capillary attraction united with evapora- tion from the exposed parts of the pebbles thus rendering it evident that the ferrocyanide might reach the summit of the gravel from below.Other substances were then submitted to the same action to de- cide the question as to the siliceous matter of the stones being in any way instrumental in the production of colour. White limestone pebbles from the south coast of Devon and baked pipe-clay un- derwent the same changes with the exception that the blue tint was not so bright and clear as was the case on the siliceous surface ; but this is considered attributable more to the perfect whiteness of the siliceous coating aiid the decidedly superficial film of prussian blue which was produced on it.Independent of this the effect can only be attributable to the action of the carbonic acid gas present in the atmosphere slowly deconipoeing the ferrocpatiide of calcium and generating the blue stain. 6s. " On the Preparation of Malic Acid from Culinary Ithubarb," by Thomas Everitt Esq. (See Memoirs Art. 32. Vol. I.) * See Proceedings of Chemical Society p. 35. rol. i. 48 February 21 .--?‘he President in the Chair. Mr. James Napier was elected an Associate Member. The following gentlemen were proposed by the Council as Officers and Members of Council for the ensuing year in the room of those who retire in accordance with laws Nos. 1,2 and G :-Arthur Ailtin Esq. President ; Thomas Graham Esq.Vice-President ; Robert Porrett Esq. Treasurer;Michael Faraday D.C.L. William Gregory M.D. William Hasledine Pepys Esq. John P. Gassiot Esq. and W. 1-3. Leeson M.D. as Members of Council. The following communications were read :-69. “A short Notice from NIr. Francis announcing the separation of Theine from the Ilex Paraguayensis or Yaraguay ‘Fen,” by Dr. Stenhouse. 70. Extract from a letter from Professor Henry Croft “ On the Manufacture of Sugar from the Zea Mays.” Experiments have been made in the State of Indiana which seem fully to prove that the stalks of the maize may be employed advan- tageously for the manufacture of sugar. It is well known that the sugar-cane as grown in Louisiana does not produce abovc one-third as much saccharine matter as when raised in Cuba and other tropical situations.In Louisiana one acre yields from 900 to 1000 11)s. of sugar and it appears that 1000lbs. inay be obtained from the stalks of the maize. The juice of the latter contains more than three times as much sugnr as the juice of the bect-root and five times that of the maple. By plucking off the ears of the maize as they begin to form the saccharine matter of the stalk is grcatIy increased. The maize-stalks require less pressure and the whole of the stalk can be used afterwards affording a good fodder for cattle. Thc plant can be raised with the greatest ease in from seventy to ninety days whereas the sugar-cane requires much care and attention and does not arrive at maturity in less than eighteen months.49 March 7.-.lohn T. Cooper Esq. Vice-President in the Chair. James Thomson Esy. F.R.S. Edmund P. Thornson Esq. Charles l’homson Esq. William Stilrk Esq. .Jncoh Bell Esq.. and George Gow Jun. Esq. were elected hlembers. The following communications were read :-7 1. “On the Astringent SubsGnces ” (continued) by John Sten-house Ph. D. (See Memoirs Art. 34. T’ol. I.) 72. “ On fithogen and the &:thonitlee,” by IYilliam H. Bal-main Esq. On the Gch of December 184.2,I communicated to the Society the discovery of a new compound of nitrogen and boron which Mas named “Bthogen,” and which like cyanogen combined with the metals. At that time hopes were held out that I shou1tl be able to furnish the Society with an analysis of zthogen and the results of further experiments but I am still without tlie means of doing the former and have been prevented by illness from -c\.cjrl<ingmuch at the latter.Hoiyever wme experiments nhich 1 have been able to make have brought out very easy processcs for preparing zthogen and the ztbonides which niny be interesting to chemists and n-ill place at their disposal a ready mcanL; of obtaining these very StdJle compounds which niay prove powerful agents rKtliogen W;IS originally obtained by hcating together n mixture of boracic acid and melon and the principai dificulty ;ttteiidant upon the process was tlie previous preparation of the melon. ,411attempt having been made to form melon by heating together bicymide of mercury and sulphur it appeared that melon was formed but n-as with difficulty separated from the sulphuret of mercury which accmi-paxiied it ; but as the presence of tlx dpliuret cf rnercury (foes not interfere .cr.itli the formation of aethogcn froin a mixture of riielon and lioracic acid that substance may be obtained by siniply hent- ing together 5 parts of sulphur 38 of bicpiide of mercury and 7 of anhydroiij boracic acid or by heating togcther sulldiocyano- gen and boracic acid.Hwing an easy procws for lrepiuing xttio- gen it was advisable in the next place to hare a marc reid:,. inetliotf of forming the ztlionitles tlim that of lienting togethtr athogen ;trtd the metals which is a long and uncertain proccs.s au:i :ti1 atterq)t was made to form zthonides by heating rctliogeri with the sulpliuwts of the metals.As mic lit be expectcd from tlic st,!l)ility of atliogcii and its strong affinity for thc metals the xthogen ilil-c-ctiy displaced the sulpliur and forid the atthoriide. ITpmfurtlii-r cxperimel;~it was proved that the athonides might be nmic 11~-heating sulphur bicyanide uf mercury aiid boracic acid with the ~n~tallir: siilphurcts. The praportions should be such as would give riw tc tlic> presence of 2 atonis of the met;dlic sulphuret 2 atoms of bontcie itcid (sup-posing its conipo:itim to be BO,) 3 atonis of cyai~qen,ant1 3 ;ltoiuL of free sulphur. The zthoiiitles when thus formed iire not quite 1)iire hut may be readily purified by boiling with a !Gstu:e of nitric and rnurLitic acids ChP?,l.P?-oc.-No. T‘. 50 and afterwards washing carefully. In this way zthonides of sodium iron copper and lead have been formed. Common galena was need for the zethonide of lead ; and for that of iron,,iron filings and an ad-ditional quantity of sulphur. These four athonidss are all perfectly white and infusible ; before the blowpipe they yield the very beauti- ful phosphorescent light alluded to in a previous communication and in all respects resemble the aethonides of potassium zinc lead and silver whieh were described as being made by the other processes. In conclusion I beg to draw the attention of the Society to the remarkable stability of these compounds asd the very strong affii. ties of athogen. Bthogen attracts moisture from the air with great avidity and decomposes it so rapidly that a portion of aethogen which I have kept in a moderately well-stoppered bottle smells strongly of ammonia.The want of means must still be my apology for not furnishing the Society with a quantitative analysis but if any member of the Society will undertake one I shall be most happy to supply him with a fair specimen of aethogen. 73. ''On the Exhalation of Carbonic Acid from the Human Body," by E. A. Scharling Professor of Chemistry in the University and Polytechnic School of Copenhagen. Communicated by S. Elliott Hoskins M .D. With the view of ascertaining the quantity of carbonic acid ex-haled during the twenty-four hours as well from the lungs as from the general surface of the body Professor Scharling undertook the following experiments on six individuals viz.four males and two females. The subjects of experiment were confined in an air-tight box wherein they were perfectly at their ease being enabled to speak eat sleep or read without incoiivenience ; a constant current of at-mospheric air was admitted into the box and the deteriorated gases abstracted by means of an air-pump. The air withdrawn was con- ducted into a proper arrangement of bottles some containing sul- phuric acid others a solution of caustic potash. The quantity of carbonic acid both previous to and subsequent to each operation was carefully ascertained by being received into three graduated tubes. The results were as follows :-1st. The Professor himself aged thirty-five years exhaled 219 granimes" during twenty-four hours seven of which were spent in sleep.2nd. A soldier twenty-eight years of age exhaled 239,728 grammes = 5-45 oz. 3rd. A lad of sixteen 224.379 grammes =7-9 02. 4th. A young woman aged nineteen 165.347 grammes=5*S3 02. 5th. A boy nine years and a half old 133.126grammes =4-6902. 6th. A girl of ten 125.42 gramrnes =4-42 02. In the two last cases the period allotted to sleep was nine hours. From these experiments the Professor deduces that males exhale * =7-72 02. avoirdupois. 51 more carbonic acid than females and children comparatively more than adults. He also finds that less of this gas is given off during the night than during the day ; and that in certain cases of disease which he does not specify less carbonic acid is formed than during the healthy state.He is thence induced to hope that attention to this point may ultimately throw some light on certain forms of disease. it will be interesting to compare these results with Liebig’s views as well as with the experiments which have recently emanated from the French Acaddmie des Sciences. March 21 .-The President in the Chair. Twenty-four specimens of rare chemical products were presented for the Society’s Museum by Professor Liebig. Col. Yorke ex-hibited a specimen of magnesium obtained by voltaic action on the chloride of magnesium. The following papers were read :-74. ‘‘ On Theiiie,” by John Stenhouse Ph. D. (See Memoirs Art. 35.Vol. I.) 75. “ Observations on M. Reiset’s Remarks on the New Method for the Estimation of Nitrogen in Organic Compounds and also on the supposed part which the Nitrogen of the Atmosphere plays in the Formation of Ammonia,,’ by Heinrich Will Ph. D. (See Memoirs Art. 33. Vol. I.) March 30.-Anniversary Meeting the Presideiit in the Chair. ‘fie following Report of the Council was read by the President and subsequently ordered for publication :-Report of the C~uiaCilmade to the Chemical Society of Londoii March 30 1843. THEcompletion of a second year of the Society’s existence in cir- cumstances of increasing prosperity enables the Coiincil to congra- tulate their fellow-members on the positive attainment o€ the prin- cipal objects for which they are associated.The Society continues to be augmented in numbers and influence by the election of new Members and has been well supported by contribntions of original papers read at its meetings. The papers presented appear to in- crease both in number and value ; and any apprehension of a want of papers which formerly existed has been in a great measure dis- pelled by the experience of the last Session. It is now sufficiently evident that ample materials exist in England for il Chemical So-ciety and you have furnished unquestionable proofs of the utility of 52 such a Society in its power to advance the cultivation of chemical resesrch in the cguntry. ?‘liirtj-two Members have been elected into the Society since the last Anniversary.Our present numbers are-7 7 Members resident in London 57 Members resident in the country or ‘‘non-resident ” Members 10 Associates and 3 Foreign Members making a total of 147 Members with an annual income of 55211. The Society has thus early in its career to deplore the loss by death of two iMembers. HENRY Eeq. F.R.S.,who took an active part in the esta- HENXRLL blishment of the Society and was a member of the Council first elected. hh. Hennell will ever hold an honourable place in the history of chemistry as the discoverer of sulphovinic acid one of the earliest achievements in organic chemistry and which has since formed the starting-point for numerous important inquiries. Mr. Hennell was destroyed by a lamentable accideiit which no intelli- gence could have foreseen in tlie discharge of his professional duties as Chemical Operator to the Apothecaries’ Hall in the 45th year of his age.The shock of this deplorable event still unfits us from calmly estimating the scientific merits and highly amiable character of our lost friend. And Mr. HENRY INGLIS,of Kincaid Print Works near Glasgow who besides cultivating successfully the chemistry of calico-printing was distinguished for his accurate knowledge of the general science in the progress of which he took much interest. Mr. Inglis whose constitution was always delicate did not outlive his 43rd year. At the conclusion of last Session the Couiicil made a new arrange- ment with the Society of Arts for the use of two rooms for their meetings and a place of deposit for the property of the Society.These arrangements they have reason to helieve have given general satisfaction to the Members. The Society published the ‘rhird Part of its Proceedings and Memoirs in August last and has another Part at present passing through the press the great extent of which bas occasioned some delay in its publication. There have been received since last Re- port 41 communications from 21 contributors of which 20 are printed entire in the 3rd and 4th Parts and full abstracts given in the Proceedings of the remaining 2 1. These communications are the fruit of numerous and varied inquiries and form in the opinion of the Council a contribution of some importance to the progress of the science. The Council would refer in particular to the full ex- amination and discussion which the process of hlM.Will and Var- rentrapp for the detcrmination of nitrogen has received by the ex- periments of Mr. Francis and Dr. Fownes and more lately in Dr. Will’s own comprehensive memoir ;-to the series of useful papers on astringent substances which they owe to their valuable con- tributor Dr. Stenhouse ; and to the papers on various subjects con- nected with the metals and the salts by Professors Liebig and Gre- gory RIesers. Porrett Croft Cock Ralmain and Warington and on organic substances by Professors Liebig Johnston Everitt Dra. 53 Playfair and Fownes ; on agricultural subjects by Dr. Schweitzer and Mr. Chatterly ; on voltaic electricity by Mr.Arrott and on the heat disengaged in combinations by the President. The Council still presses upon these and other contributors not to relax their ex- ertions and invites the Members generally to communicate the re- sults of their inquiries. The Society has also received presents of interesting chemical products and crystalline specimens for their collection from various donors particularly Mr. Warington and Professor Liebig. They have also received several chemical works from their respective authors. The Council call attention to this nucleus of a collection which has been formed and which they hope will be rapidly in- creased by the exertions and liberality of the Members. The Council has also lately made arrangements for procuring the leading chemical Journals and circulating them among the Members.The condition of the Society’s finances is highly favourable as will appear from the following audited report of the Treasurer. Auditors’ Report. We have examined the accounts of the Chemical Society of Lon-don presented by Arthur Aikin Esq. as Treasurer and find the monies received to amount to- $2 8. d. For Subscriptions ...................... 161 0 0 Balance of former Audit ................ 146 16 8 307 16 8 And the Expenditure (for which vouchers have beenshown) ........................ 38 1 5 Balance in favour of the Society. ..... 269 15 3 With the Bankers Messrs. Coutts and Co... 263 17 3 In the hands of the Treasurer ............ 5 18 0 6269 15 3 WM.HAELEDINE PEPYS J.P. GASSIOT. London March 23rd 1843. The following gentlemen were elected as Officers and Council for the ensuing year :-President.-Arthur Aikin Esy.,F.L.S. F.G.S. Vice-Presidents.-William Thomas Brande Esq. ; John Thomas Cooper Esq. ;Thomas Graham Esq. ; Richard Phillips Esq. Treasurer.-Robert Porrett Esq. Secretaries.-Robert Warington Esq. and George Fownes Ph. D. Foreign Secretary .-E. F. Teschemacher Esq. Council.-Dr. Charles Daubeny ; Thomas Everitt Esq. ; Michael Faraday D.C.L. ; ,J. P. Gassiot Esq. ; Dr. William Gregory ; Per- 54 cival N. Johnson Esq.; James I?. My.Johnston Esq. ; Dr. W. B. Leeson ; W. Hallows Miller Esq. ; W.Hasledine Pepys Esq. ; Dr. G. 0. €tees ; Lieut.-Col. Philip Yorke. The thanks of the Society were given to the Officers and Council for their exertions during the past year.April 4.-The President Arthur Aikin Esq. in the Chair. “ The Guide to the Urinary Cabinet,” by R,Venables was pre-sented by Mr. George Knight Jun. Messrs. Knight and Sons exhibited their Urinary Cabinet. Professor Graham exhibited Dr. Mohr’s subliming apparatus as improved by Dr. Stenhouse. Mr. Garrod exhibited several fine specimens of Theine Caffeine and Theobromine. Edward Beaumont Pitchford Eeq. and John H. Pepper Esq. were elected Members. The following communications were then read ;-76. ‘<On the Subsulphates of Copper,” by J. Denham Smith Esq. (See Memoirs Art. 36. Vol. I.) 77. On the Spontaneous Decomposition of the Chlorate of Am- 8‘ monia,” by Mr.Joseph Wonfor. Having occasion lately to prepare a quantity of this salt the phae- nomena which form the subject of this communication were ob-served. The salt was prepared by adding to a saturated boiling solution of bitartrate of ammonia a saturated boiling solution of chlornte of potassa the liquor being strained from the precipitated cream of tartar and cooled as rapidly as possible it being observed that the ammoniacal salt underwent a change if allowed to remain at a high temperature for any length of time; the solution was then care-fully evaporated at a temperature below 100’ Fahr. and again strained from a small portion of cream of tartar which separated as the liquor was concentrated. The chlorate of ammonia ciystallizes in small acicular crystals or in plates similar to the chlorate of PO-tassa.The crystals are very soluble both in water and alcohol and have a sharp cooling taste. This salt was partially examined by Vauquelin but he does not appear to have observed the change it undergoes at the ordinary temperature of the atmosphere which most likely arose from his using the salt immediately after it was prepared. In Murray’s ‘ Elements of Chemistry,’ vol. ii. p. 544 it is stated that Vauquelin examined this salt the author remarks “ it crystal-lizes in fine needles and appears to be volatile as there is a consider- able loss on evaporating its solution ; its taste is extremely sharp ; it detonates when placed on a hot body with a red flame ; decomposed by heat it gives out chlorine gas with nitrogen and a little nitrous oxide hydrochlorate of ammonia with hydrochloric acid remaining.” Brande states in his Elements,’ on the authority of Vauquelin 55 ‘I (Ann.de Chim. xcv. 97) that this salt probably consists of one proportional of each of its components or 17 of ammonia + 76 of chloric acid ; but its composition has not been experimentally de- termined.” I have analysed the salt by decomposing it with caustic potash collecting the ammonia in water acidulated with hydrochloric acid and evaporating the solution carefully to dry- ness ; the chloric acid W~EIdetermined by igniting the salt after the action of potash in a porcelain capsule ; then calculating the amount by the weight of the resulting chloride of potassium my results gave one equivalent of ammonia one of chloric acid and one of water.After the salt had been prepared a few days the colour was ob-served to have changed from white to lemon-yellow and gave out an odour which powerfully affected the nose when held over the un- corked bottle irritating the eyes much more than chlorine and cau- sing a flow of tears ; this odour was dissimilar to that of any of the oxides of chlorine. The salt was put away till an opportunity should offer of examining the cause of this change. On going into the laboratory some days after the alteration in the appearance of the salt had been observed the bottle which contained about 4 ounces was found broken into innumerable particles and the remains of its contents strewed about the floor; on inquiry I was informed that during my absence it bad exploded with a loud report.Imagining the explosion was produced by the bottle being closely stoppered an ounce of the salt was introduced into a very strong phial and con- nected with a vessel containing a solution of nitrate of silver through which the products of the decomposition had to pass the unab- sorbed gases being collected in a jar at the pneumatic trough hoping to collect the gases as they were liberated. After gaseous matter had been quietly evolved for twelve hours it exploded with greater violence than before no portion of the bottle remaining (except the neck) larger than a pea. A quantity of chloride of silver had pre- cipitated from the nitrate and the gas jar contained free nitrogen.Another portion of the salt was then placed on a sand-bath the temperature of which was about 120° Fahr. ; this soon underwent decomposition but only detonated slightly giving off dense white fumes with the smell of nitrous acid. Finding the salt was so easily decomposed I proceeded to ex- amine more closely the nature of the changes that took place. 20 grains of the salt were introduced into a strong flask connected as in the previous experiment with a vessel containing solution of ni- trate of silver but with the mercurial instead of the pneumatic trough ; the flask was then very carefully warmed by a spirit-lamp ; the salt instantly exploded with great violence and a loud detonation breaking the flask to atoms.Five grains of the salt were then ope- rated upon without the vessel containing the solution of the silver salt and the products of the decomposition collected over mercury ; they were nitrogen chlorine nitrous acid and water with a little chloride of ammonium; but from the rapidity with which the gases were eliminated it was impossible to collect the whole of the pro-ducts of the decomposition though the experiments were repeated 56 six or seven times both with and without the vessel containing the solution of nitrate of silver. When five grains of the salt were em- ployed the tubes (which were filled with mercury when no salt of silver was used) were not broken ; still the action was so energetic that it did not allow of accurate indications of the quantity of the gases evalved being obtained.From the presence of free nitrogen and chlorine both in the pro- ducts of the spontaneous and produced decomposition I am led to conclude that chloride of nitrogen is formed; but as the whole of the products were in no case obtained it was impossible to deter- mine this experimentally. April 18.-The President in the Chair. The ‘‘American Journal of Science for 1S43,” presented from the Editors. *‘ A Description of a new Carbon Voltaic Battery,” by B. Silli-man Jun. Esq. A.M. from the Author. Mr. Bullock exhibited some scarce cliemical products. Dr. Heinrich Will of Giessen was elected a Foreign Member. S. Elliott Hoskins M.D. and William Brotlripp Itandall Esq. were elected Members.The following papers were then read :-78. “ On the Spontaneous Change of Fats,” by W. Beetz. (See Memoirs Art. 37. Vol. I.) ’79. “On certain Improvements in the Instrument invented by the late Dr. Wollaston for ascertaining the Rcfracting Indices of Bodies,” by John Thomas Cooper Esq. (See Alemoirs Art. 38. VOl. I.) May 2.-?Vm. ‘rhos. Brande Esq. F.R.S. Vice-President in the Chair. Mr. Bullock presented a specimen of iodine and hlr. TbTilrreKlDe la Rue one of the ferriclcyanide of iron to the Socicty’s Museum. Thomas Burrows Esq. was elected a hlemher and Mr. ,Joseph Wonfor an Associate Member of the Society. Tlic following communications were then read :-SO. “ Some additional Remarks on Theine,” by Joh Stenhouse Ph.I). (See Memoirs Art. 39. 1701. I.) 81. “ Note on the Preparation of rEther,” by Gcorge Fownes Ph. I>. The beautiful experiments of Rlitscherlich on tLe indefinite con- version of alcohol into zther by the same qumtity of bulphuric acid seem to point out the possibility of effecting 11 great iniprovenicnt in the ccoiiomical production of that important substance. It is well known that in the old process in which equal weights of arid and spirit are subjected to distillation a large quantity of alcol~ol 57 escapes stherification at the commencement of the process owing to the low boiling-point of the mixture and on the other hand much is destroyed towards the end of the distillation by the excess- ive heat ; the limits of temperature within which aether is generated in quantity being as is well known rather narrow ranging perhaps between 280' and 320'.In the continuous operation described by Mitscherlich such a mix-ture of alcohol and sulphuric acid is made that its boiling-point shall be well within the &her-producing limit while into this mixture maintained in a state of rapid ebullition alcohol is suffered to flow in such proportion as exactly to replace the liquid which distils over and which liquid is seen to consist of a mechanical mixture of aether and water with a very small quantity of unaltered alcohol. So long as the temperature is properly maintained by due regulation of the fire and the flow of alcohol the distilled products do not vary and the process itself may be it is said continued until the oil of vitriol becomes gradually destroyed by the impurities of the spirit or lost by volatilization.In this experiment absolute alcohol is used ; in the practical manu- facture of aether however this is obviously impossible ; it occurred to me therefore to try experimentally how far the process might be carried if ordinary rectified spirit were substituted. It is stated in- deed by Liebig that under such circumstances Etherification is put a stop to by the accumulation of the water introduced with the ale coho] gradually depressing the boiling-point of the mixture below the temperature at which Ether is formed and that this happens when the whole quantity of spirit used amounts to four times the weight of the oil of vitriol (Annalen der Pharmacie xxx.136). It is difficult to see how this could happen if attention were paid to the temperature of the boiling liquid since it would seem easy to regulate the point of ebullition so as always to maintain the acid of the same degree of concentration with respect to water. A niixture was made of 6 02. by weight of concentrated sulphuric acid and 32 02. by weight of rectified spirit of sp. gr. -836 at 60°. This mixture was introduced into a wide-necked flask fitted with a cork pierced with three holes for the purpose of receiving a thermo- meter a narrow tube connected with a reservoir of alcohol of the same density as that mentioned above and a wide tube for convey- ing the vapours to the condenser which was a common metal worm immersed in cold water.These arrangements being completed an Argand gas-lamp was placed beneath the flask and the contents made to boil; the thermometer speedily rose to near 300' F. A slender stream of spirit was now allowed to mix with the boiling liquid in such quantity as to maintain at once an invariable tem- perature and rapid and violent ebullition. It was soon found that by a little management the thermometer could be kept quite sta- tionary at any required point within the limits before referred to. At 300° and thence to 360° the separation of the distilled products into two strata was very distinct and beautiful ; at 280' to 290° enough alcohol passed over unchanged to prevent this separation Chem. Proc.-No. IT 58 until a little water had been added.There was a slight trace of sulphurous acid and the mixture in the flask gradually deepened in colour until at last it became nearly black without however in the slightest degree losing its efficiency. At this period the process had been kept up about fifteen hours ; more than a gallon of alcohol-twenty times the weight of the acid- had passed through the apparatus and as the activity of the opera- tion remained to the last unimpaired it seems fair to infer that its only limits are the loss of sulphuric acid by volatilization and the formation in small quantities of secondary products such as oil of wine sulphurous acid and olefiant gas. * The rether obtained was mixed with some caustic potash and rec- tified by the heat of warm water; its sp.gr. at 60' was 0730,and it measured fully three pints. As merely water at 55O was used for condensation in place of ice much loss of vapour must have oc- curred ; and since the residual alkaline liquid yielded a large quan-tity of alcohol by distillation the process must be considered on the whole a tolerably productive one although still vei-y far from what might be. desired. Of cour~e,on a large scale much of this loss would be avoided. It was remarked that during the whole of the operation even when the temperature was purposely kept so low as to allow much alcohol to escape decomposition a considerable quantity of perma- nent gas made its appearance. By adapting to the lower end of the worm of the condenser a two-necked receiver furnished with a bent tube dipping under water it was easy to collect and examine this gaseous matter.When purified from Ether-vapour by washing with oil of vitriol it was inflammable burned with much light and pos-sessed the peculiar alliaceous odour characteristic of purified olefiant gas. Its production became much increased by a rise of tempera- ture ; at 310' it passed in a rapid succession of large bubbles. There appears no difficulty then in applying Mitscherlich's con- tinuous process to the economical manufacture of Ether on the great scale ; it is very probable too that by avoiding the use of a naked fire much of the secondary action to which allusion has been made might be prevented while by a proper condensing arrangement the waste obvious in my own experiments would be avoided.The most advantageous temperature could be determined by experience in a very short time and with this knowledge the process might be con- ducted ever afterwards in such a manner as to yield a perfectly uni- form product. A somewhat low temperature about 280' to 290° might possibly be the most advantageous since it would be better to let a little alcohol escape aetherification than to use heat enough to occasion the abundant production of oil of wine and olefiant gas. This alcohol is easily recovered after the rectification of the Ether. It may be proper to mention also that the mixture in the distillatory vessel may be repeatedly suffered to cool and again reheated with- out injury.59 May 16.-The President in the Chair. Mr. Warington presented a specimen of the sulphate of chromium and potash (chrome alum) in large crystals to the Society’s Mu- seum. “ On the Heat of Chlorine Bromine and Iodine developed during the formation of the Metallic Compounds,” by Thomas Andrews M.D. from the Author. The Council submitted to the Meeting a resolution that the So-ciety should hold its sittings on the 1st and 3rd Mondays in the month instead of the Tuesday that evening being found to inter- fere with the meetings of the Linnean Society and the Society of Civil Engineers. Moved by Richard Taylor Esq. and seconded by J. Denham Smith Esq. that such resolution be adopted. John Gardner M.D. was elected a Member of the Society and Mr.John Carty an Associate. Mr. Francis exhibited and explained the method of taking the fusing point of fatty bodies as practised in the Giessen laboratory. The following papers were then read :-82. “ On Ferric Acid,” by J. Denham Smith Esq. (See Memoirs Art. 40.Vol. I.) 83. “ On the Action of Alkalies on Wax,” by R. Warington and Wm. Francis Esqrs. (See Memoirs Art. 41. Vol. I.) 84. ‘‘ On the Action of Suhhuric Acid on the Ferrocvanide of Potassium,” by George Fowne’s Ph. D. (See Memoirs -Art. 42. VOl. 1.) The’Society adjourned to the Evening of the 1st Tuesday in November. INDEX ‘1‘0THE PROCEEDINGS. VOI,. I. AcrDs :-products of the action of ni-tric on castor oil 5 ; preparation of hydrochloric 7 ; malic 12 ; .chro-mic 17 ; conversion of benzoic into hippuric 22,33 ;pyrogallic 41,43 ; preparation of malic from culinary rhubarb 47 ;exhalation of carbonic from the human body 50; ferric -59 ; action of sulphuric on the fer- rocyanide of potassium 59.Aither oxalic Inethylic decomposition of by alcohol 19 ; preparation of 56. Zthogen 44,49. Ethonides 4.1 49. Air analysis of atmospheric 13. Alcohol decomposition of oxalic me- thylic =ether by 19. Alkalies action of on wax 59. Ammonia supposed part which the ni- trogen of the atmosphere plays in the formation of 51 ; chlorate of spontaneous decomposition of the 54. Anniversary report and address 26,5 1. Archil substances contained in the li- chens employed for the preparation of 21.Arragonite on a specimen of artifi- cial 9. Arrott (Alexander) on some new cases of galvanic action and on the construction of a battery without the use of oxidizable metals 43. .4ssafaetida oils of analysis of 15. Atomic weights revision and more exact determination of 15. Auditors’ Report 28 53. Balniain (W.H.) on zethogen and the r~tlionides 44 ; on tlie probable existence of nitrogen combined with silicon in soils and other substances 45 ; 011 rethogen and ,~jthonides 48. Beetz (W.)on the spoiitaneoiis changc of fits 56. Beiizoic acid conversion of into hip- puric acid in the animal economy 22. Brewing observations on 23. Bunsen (Prof.) on a new class of ca-codyl compounds containing plati- num 17 ; on the radical of the ca- codyl series of compounds 21.Cacodyl compounds new class of con- taining platinum 17. Cacodyl series of compounds radical of the 21. Cadmium salts of 36. Caloric agency of in permanently mo-difying the state of aggregation of the molecules of bodies 18. Carbon atomic weight of 9 11. Carbonic acid exhalation of from the human body 50. Castor oil products of the action of ni-tric acid on 5. Cetine analysis of 14. Chalk on hardening it by Prof Kuhl-man’s process for the silicification of limestones 11 ; analvsis of the of the Brighton cliffs 26. Cliatterly (hi. W. F.) on saline ma-nures containing nitrogen 41. Chlorate of ammonia spontaneous de- composition of the 54. Chromic acid preparation of I7 ; em-ployment of as a11 agent in galva-nic arrangements 18.Chromium and potash new oxalate of 23 ; additional observations on the red oxalate of 40. Clark (Dr.) his method of ascertain- ing the hardness of water 8; on the revision and more exact determina- tion of atomic weights 15; on a gas-burner for a laboratory table 35. Cock (W.J.) on the production of artificial uranite 38 ; on palladium its extraction and alloys 4G. Conprr (Johu T.) on improvements 62 INDEX. in the instrument invented by the late Dr. Wollaston for ascertaining the refracting indices of bodies 56. Copper and other ores combined with sulphur mode of treating 8 ; sub-sulphates of 54. Council and officers in 1841 2 ; in 1842 29 ; in 1843 53.Croft (Henry) on the decoinposition of oxalic inethylic Ether by alcohol 19; on a new oxalate of chromium and potash 23 ; on some salts of cadmium 36 ; on the manufacture of sugar from the Zea Mays 48. Cudbear substances contained in the lichens employed for the preparation of 21. De la Rue (Warren) on the agency of caloric in permanently modify- ing the state of aggregation of the molecules of bodies 18. Detmer (M.) on bleaching salts 5. Dumas (M.)on the analysis of at-mospheric air 13. Equivalents of the phosphorus family of elements division by three of the 44. Ethal analysis of 14. Eucalyptus on the sugar of the 47. Everitt (Thos.) on the preparation of malic acid from culinary rhubarb 45.Fat formation of in the animal body 46 ; spontaneous changes of 56. Ferric acid 59. Formation of the Society and list of original members 1. Fownes (George) on the preparation of artificial yeast 26 ; 011 the prepa- ration of hippuric acid 33 ; on two specimens of South Sea Guano 36 ; on the analysis of organic substances containing nitrogen 41 ; on the pre- paration of Ether 56 ; on the action of the sulphuric acid on the ferro- cyanide of potassium 59. Francis (W.) on the determination of nitrogen in orgnnic analysis 44 ; action of alkalies on wax 59. Garrod (A. Baring) on the conver-sion of benzoic acid into hippuric acid in the animal oeconomy 22. Galvanic action some new cases of 43. Graham (Prof.) on the preparation of clilorate of otash 5 ; on the con- stitution of t!e sulphates as illus-trated by late thermometrical re-searches 22 ; on heat of combina-tions 41 ; on the division by three of the equivalents of the phosphorus family of elements 44.Gregory (Dr. W.) on a simple and cheap method of preparing pure hy- drochloric acid and of any required strength 7; on a new method of obtaining pure silver in the metallic state or in the form of oxide 47. Guano on two specimens of South Sea 36. Hagen (R.) on malic acid and its salts 12. Heat specific and conducting power of building materials 24. Hippuric acid conversion of benzoic acid into in the animal economy preparation of 33. Hutchinson (John) on the specific heat and conducting power of build-ing materials 24.Hydrometer and saccharometer mode of reducing the indications of the to each other 16. Hyssop oils of analysis of 15. Ilex Paraguayensis separation of theine from the 48. Iron artificial magnetic oxide of 14. Jolinston (J. 1:. W.) on the sugar of the Eucalyptus 45. Kuhlnian (Prof.) on chalk hardened by his process for the silicification of limestones 11. Liebig (Prof.) on the preparation and formation of yellow pnissiate of potash 2 ; on the atomic weight of carbon 9; on the preparation of' cyanide of potassium and its appli- cations 24 ; on the formation of' fat in the animal body 46. Light flashes of observed during the crystallization of nitrate of stron- tian 5.Malic acid and its salts 12 ; prepara-tion of from ciilinary rhubarb 47. Manganese protosulphate of action of chromate of potash on the 30. Manures saline experiments with containing nitrogen 41. Marchand (Dr. R. F.) on the atomic weight of carbon 11. Maugham (Mr.) on the mode of treating copper ores and ores of other metals coinbiiied with sulphur to ascertain the quantity of sulphur INDEX. 63 in such ores and also the quantity of copper in the native sulphuret 8. Mellon formation of 5. Mercury change of colour in the biniodide of 23. Metals oxidizable construction of a battery without the use of 43. Milk formation of in the animal ceco- nomy 46. Miller (Prof. W. €I.) extract from a letter from 29.Nitric acid products of the action of on castor oil 5. Nitrogen analysis of organic sub- stances containing 41 ; cletermina-tioil of in organic analysis 44 ; on saliiie manures containing 44. probable existence of combined with silicon in soils and other substances 45 ; observation on hl. Reiset’s re- marks on the estimation of in or-ganic compounds 51. Officers and council in 1811 2; in 1842 29; in 1843,53. Palladium its extraction and alloys 4G. I’arnell (E. A.) on the forniation of niellon 5 ; 011 the influence of water in chemical reactions 15 ; on tlie equilibriuni of the temperature of bodies in contact 32. Piesse (Septimus) observations on brewing 23. Platinum new class of cacodyl com- poiuids containing 17.Playfair (Dr. Lyon) 011 the formation of milk in the animal Ceconomy 4G. Porrett (Robert) on a curious forma- tion of prussian blue 32. Potash yellow prussiate of prepara- tion and formation of 2 ; preparn-tion of the chlorate of 5; chro-mium new oxalate of 23; chro-mate of action of on the protosal- phate of aanganese 30 ; chro-mium additional observations on the red oxalate of 40. Potassium,. preparation of the cyanide of and its applications 24 ; action of the sulphuric on the ferrocyanide of 59. Prussiaii blue curious formation of 35 ; formation of upon the surface of gravel through tlie medium of ferrocyanide of calcium 47. I’yrogallic acid 41 ; astringent sub-staiices as sources of W. Pyroxjlic spirit on 12.Redtenbacher (Prof.) on the atomic weight of carbon 9. Reiset Observations on his reinarks on the estimation of nitrogen in organic compounds 51. Report Auditors’ 28 53. Saccharometer and hydrometer mode of reduciiig the indications of the to each other 16. Salts bleacliing 5 ; of malic acid 12. Scanlan (M.) on flashes of light ob- served during the crystallization of nitrate of strontian in the dark 5. Scharling (Prof. E. A.) on the ex-halation of carbonic acid from the human body SO. Schunck (Edward) on some of the sub- stances contained in the lichens em- ployed for the preparation of arcliil and cudbear 21. Schweitzer (Dr. E. G.) on the ana- lysis of the chalk of the Brighton cliffs 29. Silver new method of obtaining it pure in the metallic state or in the form of oxide 47.Sims (Olice) on phosphate of yttria 7. Smith (J. U.) on the subsulphates of copper? 54 ; on ferric acid 59. Stenhouse (Dr J.) on the analysis of cetine and ethal 14; on the ana- lysis of the oils of laurel turpentine hyssop and assafcetida 15 ; on py- rogallic acid 41; onsome astringent substances as sources of pyrogallic acid 43 ; on astringent substances 49 ; on theine 51 ; additional re-marks on theine 56. Strontiaii nitrate of appearance of flashes of light observed during the crystallization of 5. Sulphates constitution of the as illus-trated by !ate thermometrical re-searches 22. Sulphur mode of treating copper and other ores combined with a.Sulphuric acid action of on the ferro- cyanide of potassium 59. Theiiie 51 ;additional remarks on 56. Thomson (‘T’. S.) on the artificial mag- netic osidc of irori 14. Tilley (T. G.) on sonie of the pro-ducts of the action of nitric acid on castor oil 5. ‘Turpentine analysis of oils of laurel 15. 64 INDEX. Uranite production of artificial 38. Ure (Dr. Andrew) on pyroxylic spi-rit 12. Warington (R.)on the mode of re-ducing the indications of the sac- charometer and hydrometer to each other 16; on the pre laration of chromic acid 17; 011 the employ- ment of chromic acid as an agent in galvanic arrangements 18 ; 011 the change of colour in the biniodide of mercury 23 ; on the action of chro-mate of potash on the protosul hate of manganese 30; additiona! ob-servations on tlie red oxalate of chromitm and potash 40; on :he formation of prussian blue upon the surface of gravel through the me- dium of ferrocyanidc of'calcium 47 ; 011 the action of alkalies on wax 50.Water method of ascertaining the hardness of 8; influence of in che-mical reactions 1.5. Wax action of alkalies 011 59. Will (Dr.) on M. Reiset's remarks on the estimation of nitrogen inorganic compounds 44 51. W ollaston (Dr.) improvements in the instrument invented by the late for ascertaining the refracting indices of bodies 56. Wonfor (Joseph) on the spontaneous decoiiiposition of the chlorate of ammonia 54. Yeast artificial preparation of 26. Yorke (Col.) 011 a specimen of artifi-cial arregonite 9.Yttria phospbate of 7. Zea Map,manuftwture of sugar from the 48. Printed by Iiichord and .John E. Taylor Xed Lion Court ReeI Strect.

ISSN:0094-2405    

DOI:10.1039/MP842010A001

出版商:RSC    

年代:1841

数据来源: RSC

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Mr. Detmer on Bleachhg Salts. 11. On Bleaching Salts. By M. DETMER ESP. Read April 27 1841. ASHORT time ago a notice was published by M. Millon ’ on the Bleaching Salts of Chlorine in which a new view was offered of the constitution of these com ounds. They have for some time pastgenerally been consi 1pered as compounds or mixtures of a metallic chloride with a hypochlorite of a metallic oxide ; bleaching powder or the chloride of lime for instance as consisting of chloride of calcium and hypochlorite of lime in single equivalents the acid of the last salt contain-ing one atom of oxygen to one atom of chlorine. The reac- tion of chlorine upon lime supposed may be very simply stated two atoms of lime take up two of chlorine; one atom * Ann. de Chitn et de Phys.t. Ixiii. 118. .1. Zbid. t. Ixvi. 172. Mr. Dekmer on Rleacliiiig SaZfs. only of the lime is decomposed of which the calcium and oxygen respectively unite with an atom each of chlorine form- ing chloride of calcium and hypochlorous acid. The hypo- chlorous acid combines with the other atom of lime. Starting froin the composition of chlorochromic and chloro- sulphuric acids which are represented by Walter and Re- gnault as chromic and siilphuric acids in which the third pro- portion of oxygen is replaced by chlorine (Cr 0 + C1 and S 0,+ Cl) Millon supposes that the bleaching chlorides have a similar relation to the peroxides of their metals. The per- oxide of calcium being Ca O, or Ca O+ 0 bleaching pow- der is Ca O+ CI or the peroxide of calcium with chlorine substituted for its second proportion of oxygen.In support of this view Millon adduces observations of his own on the composition of the bleaching compounds of chlorine with dif- ferent metallic oxides such as oxides of lead and protoxide of iron as well as potash soda and lime in which the pro- portion of chlorine was found to vary but to correspond with the excess of oxygen above one equivalent in the peroxides of the same metals. In particular potash was found to absorb two equivalents of chlorine and soda only one the peroxide ofpotassium being K 0 + 2 0 while ttie peroxide of sodium is Na O+O. The attention of the author was particularly directed to ascertain the accuracy of the latter statement.A solution of carbonate of soda was charged with chlorine gas till it acquired a yellow colour and retained not a trace of carbonic acid. The solutiou was then briskly agitated with air by which the excess of free chlorine escaped. In analyzing the solution afterwards one portion of it was treated with a few drops of ammonia and the chlorine afterwards precipitated by nitrate of silver ; another portion was evaporated to dryness for the sodium which was obtained in the state of chloride of sodium. In four experiments the liquids charged with chlorine con- tained chlorine and sodium in the followiiig proportions in 100 parts :-Sodium.... .. 47-88 45.26 46.81 44.76 Chlorine. ... 52.12 54-74 53.1 9 55.24 while if the bleaching chloride of soda contained 1 eq.of chlorine to 1 eq. of soda its composition would be 1eq. sodium ......... 46-91 1 eq. chlorine. ...... 53.09 1oo*oo The results correspond as closely RS could be expected with this theoretical statement. There can be no doubt then that ttie chloride of soda contains one of ciilorine to one ot' Mr. Detmer on Bleachiq Salts. soda. I’his is the result reqriired by Alillon’s theory the peroxide of sodium containing according to him one of oxy-gen and one of soda; but it is equally consistent with Balard’s theory that the salt is R nlixture of single equivalentsof chlo- ride of sodium and hypochlorite of soda. To determine the quantity of chlorine which water dissolves a stream of the gas was sent through water at 59O for five hours.One hundred gramnies of water were found to take up 0.663 grainme of chlorine; or 200 cubic inches of water dissolved 207 cubic inches of gas. The chlorine was estimated by converting it into hydrochloric acid by the addition of a few drops of mi-monia slightly acidulating afterwards by nitric acid and pre- cipitating by nitrate of silver. A solution of‘ 2.58 cliloride of potassium in 38.96 water was found to dissolve less chlo- rine than pure water in the proportion of’180 to 257. Chlo-rine gas being allowed to stream through a solution of 9-245 grammes carbonate of potash in 96’495 grammes of water till saturation the solritioii lost all its carbonic acid aiid took up G.681 gramnies of chlorine. Here 1 eq. of potash =590 has taken up Gti6 chlorine which is very nearly 1$ eq..of chlorine = 663. But when the quantity of free chlorine in the liqiiiti is deducted the latter is found to ccmtain only 2-34equivalents of chlorine to 1 eq. of potash. In two other experinients in which the liquid was agitated with air after beirig saturated with chlorine to allow the excess of gas to escape there were found to 1 eq. of potash 1.44 and 1-49equivalents of chlorine. The carbonate of potash therefore without doubt takes up more than a single equivalent of chlorine. But the quantity of chlorine combined with the potash is still greatly short of two equivalents the proportioti 1-equireti by M. Millon’s theory ; the peroxide of potassiuni containing two oxygen to one potash or K 0,.The conclusioii therefore is inadmis- sible that tlie chloride of potash is analogous in constitution to the peroxide of potassium. It remains to account for the property which potash is found to possess of taking up niore chlorine than is necessary to convert it into chloride of potassium and hypochlorite of potash. On transmitting chlorine through carbonate of pot-ash a stage in the absorption is very observable at which the liquid becornes all at once of a yellow colour. This happens when what remains of the potash is entirely converted into bicarbonate of potash. The suddenness of the appearance of‘ the yellow colour appears to be due to a reaction of the car- bonic acid upon the hypochlorite of potash in solution by which hypochlorous acid is set free and tinges the liquid.By the continued application of chlorine to the liicarbonate of Mr. Iletiner ou BLeiichiiig Snlts. potash it is converted into a mixture of chlorideof potassium hypochlorite of potash and free hypochlorons acid. By the ultiinate action of the chlorine all the bicarbonate of potash is decomposed the carbonic acid entirely expelled and a por-tion of hypochlorous acid remains free in solution. This formation of free hypochlorous acid does not occur with carbonate of soda owing to the much weaker affinity which that base has for carbonic acid and its forming a much less stable hicarbonate than potash does. The free carbonic acid cannot therefore react upon the hypochlorite of soda and liberate hypochlorous acid as the free carbonic acid does upon the hypoclilorite of' potash.The same formation of free hypochlorous acid occurs in a more striking degree when chlorine is sent through a solution of acetate of potash ; that solution it is well known absorbs a large quantity of gas and acquires the strong yellow colour the odour and all the other properties of free hypochlorous acid. It is here evident that by the action of chlorine upon acetate of potash chloride of potassium is formed with the binacetate of potash free liypo- chlorous acid and the hypochlorite of'potash. If the large absorption of chlorine by carbonate of potash is due to car- bonic acid it follows that caustic potash should not absorb any excess of chlorine but that the property should be con- fined to the carbonate.Accordingly in two experiments the proportion of chlorine absorbed by caustic potash was found to be as nearly as possible a single equivalent. In one ex- periment 449'1 chlorine in the other 424.8 chloriiie were taken up instead of 442.6 chlorine by a single equivalent or 589-9 of potash. Caustic potash therefore dissolves no more chlorine than caustic soda. There appears therefore to be no reason to a\)andon the old theory that the bleaching solu-tions of chlorine in alkalies and alkaline earths cont:tiii a chlo-ride anti hypochlorite for these bleaching cornpouiitls certainly do not correspond with nietallic I,eroxides as has been lately rnain tained.

ISSN:0094-2405    

DOI:10.1039/MP8410100006

出版商:RSC    

年代:1841

数据来源: RSC

摘要:

Mr. Iletiner ou BLeiichiiig SnZts. 111. On the Atomic Weight of Carbon. By Prc$ksot*s RED-TENBACHER of Prague and LIEBIG of GiesseiP. Read May 8 1841. N the arialysis by combustion of organic substances which I contain carbon and hydrogen the observation has fie-quently been made of late years that the weight of the ele-* Translated froni the original German by Dr. J. H. Gilbert. Chem.Soc. Mem. VOL. I. C Professors Redtenbacher niid Liebig meiits separately fouiid by experiment actually exceeds the original weight of the matter submitted to combustion. In the analyses we possess of naphthalin by Mitscherlich by Dumas and by Woskresensky this is particularlv remarkable. One hundred parts of naphthalin gave to Mitscherlich,- 1. 2. Carbon .............94-34 94.440 Hydrogen ......... 6*26 6-225 100'60 1O0*66.5 One hundred parts of naphthalin gave to Dumas,- 1. 2. 3. 4. 5. Carbon ... 94.2 94.22 94-27 91*9 96.9 Hydrogen 6.3 -6*30 -6.26 -6-52 6'1 -.-100'5 100*52 100*53 101.1 101*0 And to Woskresensky 100 parts of the same substance yielded-1. 2. 3. 4. 5. 6. Carbon 94.625 94,598 95.02613 93.668 94.395 94.494 Hydrogen -6.528 -6.289 -5.3830 -6.142 -6.206 -,-. 6.526 101.153 100.897 100.4098 99.810 101.601 101.020 This constant occurrence in so many carefully conducted experiments indicates a common source of error upon which it is dependent; it can only be attributed to two causes. One of these may be sought in the defects of the method of analysis the other in the supposition that the products of the combustion (water and carbonic acid) have different compo- sitions from those usually assigned to them.If indeed either water or carbonic acid contains somewhat less of hydrogen or of carbon than we at present suppose then as we calculate from the quantities found of the former bodies the excess in the analyses is diminished in the same proportion. Let us suppose for example that carbonic acid contains only 76 carbon instead of 76.457 to 200 of oxygen aiid water only 12 hydrogen instead of 12*4?95 to 100 oxygen and then we shall have no excess in any of the analyses quoted whilst the experimental come to agree perfectly with the cal- culated results. Are we then entitled to make such changes in the atomic weights proceeding as we do upon the asstimed accuracy of experiments which from the complex nature of the apparatus can make no claim to absolute precision; or 014 the Atomic Weight of Carbon.ought we not first to compare these with other experiments in which this source of’error is entirely avoided ? A yuestiori also arises whether nuphthnlin a substance the atomic weight of which cannot be determined with certainty as it enters undecomposed into no combination is 8 proper substance to select as the nieatis of determining the atomic weight of carbon or of hydrogen ? That body must indeed be rejected on this account for it is not in our power to con- trol our analytical results from a knowledge of the weight of its atom that is the suni of the atomic weights of the elements composing it.When we also consider that the naphthalin which in the above experiments was sul>niitted to conibustion in a glass tube with oxide of copper is a volatile body that it cannot be introduced into the con~bustion tube with oxide of copper that is absolutely free from moisture; and bear in mind also that owing to the volatility of the substaiice this moisture cannot previously to combustion be removed by nieans of exhaustion? we capnot doubt the existence of a source of error which must increase the per ceiitage of hydrogen beyond that which actually existed in the substance; for however sinall the quantity of this hygroscopic moisture may be it is never-theless always present; it is weighed with the chloride of calcium tube and its hydrogen added to that contained in the substance.In all analyses hitherto conducted even those in which the whole of the hygroscopic water had been removed as nearly as possible before combustion by means of exhaustion it is oliserved that the experiment iiivariably gives rather more hydrogen than is indicated by calculation. This excess amounts in good analyses to fi-om 0*1 to 0.2 per cent. It is foulid however that this in reference to the quantity of sub-stance employed in analysis is not sufficient to affect the pro- portion of the elements to the extent observed in the analyses of iiaphthalin ; the excess in those analyses is however dimi- nished when allowance is made in the calculation for this error.There exists therefore some other cause affecting the deter- mination of the equal quantity of the elementary constituents ofati organic substance in such :I manner that one of them namely the carbon when calculated tiom the quantity of car-bonic acid obtained by combustion amounts to more than the weight of the carbon which is contained in the matter analysed. On this account a new determination of the atomic weight of ctrrbon appears to be indispensable and we have united in c2 Professors Redtenbacher ard Liebig order conjointly to submit the atoiiiic weight of carbon as at present received to a severe anti accurate scrutiny. It is known that two of the most distinguished iiatural phi- losophers Biot and Arago have by means of the direct weighiiig of carboiric acid fixed upon the nuniber 1.519 for the specific gravity of that gas.'I'heir experiments were re-peated by Duloiig and Berzelius with whom as regards skill and taleiit conscieiitiousness and accuracy 110 others can be compared. The two last observers fouiid the number 1*524 for the specific gravity of carbonic acid; that obtained by De Srtussure is 1.5269. The atomic weight of carbon as calculated from the first of these is 75.530 and froni the other 76-937. There is no known gas more easily obtained in a pure state or which can more easily be distinguished from a foreign body than car-bonic acid. Any adiiiixture of atmosplieric air or of other gases can only lower its specific gravity. Experiments have lately beeii coiidiicted by Rudberg on the dilatation of gases under the influence of heat" from which lie calculates that tlie coefficient of dilatation is somewhat less thari was previously supposed ; should these experirneti ts be correct the proof of' wliich still remains to be iiiade known they do not influence the specific gravities of two gases as determined at the same temperature even supposing the re- duction to the normal temperature be made accorditig to the coefficient of dilatation as hitherto received ; if weighed at unequal temperatures however a difference is observed.In the experiments of Dulong arid Serzelius atmospheric air was weighed at 20ioC. and carbonic acid at 18' C. COII-sequently the reduction of the gas to Oo C.according to the former coefficient of dilatation gives tlie weight of air some- what too high and since this in an equal volume represents the divisor the specific gravity of carbonic acid is estimated rather too low; in all cases however the differences fall within the liinits of the errors of observation. When we remember that the deterriiinations of the specific gravities of these gases were conducted with the same balloon the sanie scales and weights and at temperatures varying very little from each other we ought riot to call in question their correctness without the strongest and niost convincing reasons. During the last twelve years a great number of weighings of the vapours of volatile bodies very rich in carboii have tieen iitdertaken in reference to this point hy Gay-Lussac * Sec TsJlor's Scientific Memoirs vol.2,pp 507 514 543. on the Atomic Weight (If Cwboia. and also by Dumas; as for instance those of alcohol =ether and acetone the results of which agree either perfectly with the specific gravity of carbon viipour as deduced from that of carbonic acid and of oxygen or indicate it to be somewhat higher; thus the specific gravity of ether vapour is 2.586 by experinlent and 2.580 tJy calculation; and that of the vnpour of alcohol is 1.6 I 38 by experiment and 1i600 by cal-cu lation. In most of' the observations of llunias the observed spe- cific gravity of bodies very rich in carbon is far higher than that obtained by calculation. Thus according to the formula C H, the specific gravity of the vapour of riaplitlialin is 4.9882;the experiment of Dumas however gives 4.528 and that of Woskresensky 4.672 from which it may with great probability be conciutled that the specific gravity of carbon vapour is rather higher than 0.421 39 or 0'842'79.The above-mentionecl atomic weights of carhon which have resulted from direct experimerit~ are contradicted by one which however we may say is quite fictitious; its adop- tion is based on the hypothesis that the atomic weights of simple bodies are multiples of that of hydrogen by whole numbers. Ths atomic weight of hydrogen is in the abstract very small and it would be strange indeed if this when mul- tiplied by whole numbers did not in many cases give a num-ber within certain limits? approaching (suppose we say of one- fourth or one-eighth of its own atom) those of bodies having higher atomic weights so that a miiltiple of the atoniic weight of hydrogen could without introducing an important error be substituted for that fijund for other bodies.For instance by dividing 1351*61 the atoniic weight of' silver by 6.2394 the atomic weight of hydrogen we obtain the nuniber ZlSg; that is to say the atomic weight of hylrogeri is contained about 216'5 times in that of silver; but even if one-half the atomic weight of the former is added to or subtracted from that of a compound of silver so sniall a variation is made in the per-centage of that metal that in many cases 216 may be taken instead of 2 16.5 the difference only affecting the fjurth figure.The error is so srnnll because the atomic weight of hydrogen is itself very small. An entire misconception of' the nature of the investig,ztion respecting chemical equivalents has led some chemists to permit themselves the license of :idding to or retrenching from their results so much as the atiiount of one-half or one fourth of an equivaleiit of hydro-gen seeing that it altered very little the relation of the num- bers to each other provided it led to whole numbers which were multiples of the equivalent of hydrogen. It is in this Professors Hedteiihacher and Liebig nianiier that the number 75 is arrived at as the atomic weight of carbon that number being very nearly the multiple of the atomic weight of hydrogen by the whole number 12.This is duubtless ari unusual mode of controlling the accu- racy ofan experimetit yet the nunibers thus modified have been admitted by many chemists. The fact that the atomic weights of simple bodies are very nearly the multiples of that of hydrogen by whole numbers is in itself nothing remarkable ; there are other numerical relations of this kind which appear far more extraordinary on the strength of which however no one woulci think of making a change in atomic weights. Thus if we add to the atomic weight ofpotassium ~kb9*92 the atomic weight of lithium which is . . . . . . . 80.33 we obtain the number. . . . . . . . . . . . . . . . 570% Aiid this divitled hy 2 gives 285*12; now this last is as near the atomic weight of sodium wliich in chemical properties is a link between the two fornier bodies as is the atomic weight of that body obtained by multiplyiiig that of hydrogen by r? whole number.Again the sum of the atomic weights of barium and of calcium divided by 2 gives very nearly that of strontium; the sum of those of chlorine and of iodine divided by 2 @ves nearly that of bromine ; and those of iron and cobalt divided byr%,give that of maiiganese. Fhere are evidently hidden connexions in these numePica1 relations with which we are uot ncquainted and to take them as criteria before they :ire uriderstood is obviously incon-sistent with the true spirit of philosophy; the same must be admitted with respect to the hypothetical atomic weight of' carbon 75 for the correcLness of which as yet no experience speaks.The early determination of the atomic weight of lead by Berzelius entirely confirmed as it is by his Inter ex-periments in 1830 is in corriplete contradiction with the cor- rectness of atomic weights as multiples of that of hydrogen. His memoir on that sub&ject is indeed highly important in reference to our own investigation and should not be hr-gotten by chemists. The following is an extract verbatim from his meiiioir *. (6 Further expeu'ments on the Atomic Weight of Lead and its Ozides.-The reduction of a metallic oxide by means of hyclrogen gas appears so simple an experinlent for deternii- niiig the atomic weight of il metal that it might be supposed * PoggendortT's Annnlen B.xix. S.310-315. on the AlomiG weight of Chrbon. the results obtained would enable LIS to settle the question whether or not the atomic weight of a metal is a niultiple of that of hydrogen; but the nearer we approach to absolute accuracy the greater are the obstacles we have to overcome in arriving at such c? point. Resides the circumstance that very few bodies submitted to analysis are absolutely free Froni all impurity or froni the substances from the compounds of which they are separated introduces a difficulty which is often not less than that of accurately cunducting the analysis itself. 6' I was of opinion that crystnllized nitrate of lead whicli is ignited in R platinum crucible until the nitric aci(l is entirely decomposed would give perfectly pure oxide of lead; but when this oxide is reduced by iiieans of hydrogen @is and the metallic lead dissolved in nitric acid lead-coloured scales which prove to be inetallic platinum remain behind.It is true the quaiitity of this residue is very small but if the result be depended upon up to the last figure then even the smallest impurity should be avoided. Crucibles of gold and of silver were also employed but these are oxidized and combine with the oxide of' lead even when the salt is introduced in small quantities into the crucible previously heated to redness ; indeed oxide of lead thus obtained is impregnated with the foreign metal to a greater exterit than when the calcination takes place in a crucible of platinum.'6 This induced me to employ carbonate of lead prepared by precipitation partly froni the acetate and partly from the nitrate of lead by means of the carbonate of' soda; and in order to avoid all admixture of the carbonate of soda with the precipitate an excess of the salt of' lead was employed; but notwithstanding this precaution and the perfect washing of the precipitate the atomic weight obtained by nieaiis of reduction oscillated in both cases between i 303.5 and 1306'0 ; and when the metallic lead was heated with pure water the latter was found to contain carbonate of soda. Carbonate of ammonia employed as the precipitant is not objectionable on this ground but partly because if special care be not taken it is difficult to obtain that reagent perfectly free from all traces of the hydrochlornte and of the sulphate of amnionia and also became during the calcination the hydrogen of the am- monia may reduce a small quantity of the oxide to the con- dition of suboxicle which though not perceptible nevertheless notably alters the result.''By the following method I think I succeeded in obtaining perfectly pure oxide of lead. Nitrate of lead is heated to redness in a platinum crucible until notliing but oxide of lead remains; this is rubbed to powder and digested in water Professors Redteddler adLiebig with twice its weight of neutral nitrate of lead for some hours; the liquid is then poured off. Tlie oxide is by this means converted into tlie basic nitrate (2 Pb 0,+ N 0,),which is dissolved in boiling water the solution filtered whilst boiling hot and then allowed to cool wheii fine scaly crystals are depositetl.These were collected washed pressed into a consistent mass and dried. The mot?ier liquor of these crystals contains a still more basic salt which precipitates on mixing it with a solution of the neutral nitrate. The liquid decanted at the commencement of the process was therefore treated in this manner in these experiments. The last precipitate which is pulverulent was thrown upon it filter and allowed to drain and whilst yet moist the inside of ;I platinum cruci1)le was coated with it to the extent of'half n line in thickness. This coating when dry adheres strongly to the crucible.Since this basic salt does iiot fuse at the temperature required completely to decompose it there is formed in this way a quantity ot' oxide of lead which it is true contains platinum when in contact with the vessel but the inner portions are quite fi-ee from that metal. In the crucible thus lined the basic salt is laid in single pieces so that after the calcination is conipleted the oxide can be re- moved without any admixture of that lining the vessel; for the crucible containing tlie salt is previous to the calcination put into a larger one having a cover and the whole is then placed in charcoal and heated to redness at which temperature the oxide does not fuse. It is very easily known when the salt is entirely decomposed for it is first converted into mininm which appears alnioct black when red-hot ; the smallest par- ticle of it can therefore be plainly distinguished.After this change is completed the heat is continued for a full half-hour and then the crucible is removed. The oxide thus ob-tained is of a beautiful lemon-yellow coloui- and it does not in the least adhere to the coating. It still possesses the glis- tening appearance of the decomposed scaly crystals. It dissolves in dilute acetic acid without changing the colour of that liquid in the smallest degree or leaving any residue which proves that it contains no miniuni. The solution moreover is not rendered turbid by the addition of nitrate of silver. 6' When this oxide was dissolved in nitric acid precipitated by sulphuric acid the filtered acidulous liquid conceiitrated and the excess of sulphuric acid expelled sulphate of lead remained behiiid from which water did not extract any traces of a copper salt aid it was xieither coloured nor rendered turbid by caustic ammonia.The lead obtained by reducing on the Atomic Weight oJCarbon. 17 this oxide by means of hydrogen dissolved in nitric acid with- out leaving any residue. The oxide is therefore pure. '' The oxide in masses riot in powder is introduced into a glass bulb blown ~rpon a barometer tube and in this it is weighed. In order to expel all moisture the bulb was heated over a spirit-lamp until the oxide assumed a dark orange red colour and a stream of dry air was then passed through it after which it was allowed to cool.The oxide regains its lemon-yellow colour by this treatment proving that no mi-nium is found for which indeed the temperature is not suffi-ciently high. The oxicle prepared in this manner is very little hygroscopic so that 13 to 14 gramriies contain at the utmost from 1.5 to 2 millegr. of moisture. u The hydrogen gas was evolved from distilled zinc and sulphuric acid and was previous to entering the bulb con- ducted through a solution of oxide of lead in caustic potass anti also through a tribe containing coarsely powdered hydrate of potass. At the commencement of'the operation and until about two-thirds of the oxide were reduced the temperature was not raised so high as to nialte the bottom of the bulb red- hot ; when this precaution is neglected beyond certain limits a portion of the oxide of lead combines with the glass and is not subsequently reduced.It was on this account that the oxide was introduced in masses which only touched the glass at a few points; free access between the pieces was moreover by this method afforded to the hydrogen. The first eflect of the hydrogen gas is to convert the oxide into suboxide owing to which the inasses become of a dark gray colour; their form and size is not otherwise changed although the tempe- rature is higher than is required for their fusion supposing them to consist of metallic lead. As soon as the glass begins to be red-hot at the bottom small globules of lead are seen to form and the whole is graclual!y converted into fused metdlic lead.Of the portions of oxide of lead which were afterwards analysed only two were obtsined by one and the same opera-tion; all the others were separately prepared so that a fault in the preparation of the oxide cannot introduce a constant error into a11 the analyses; this however might easily occur if the same specimen of oxide had been employed in all the d i ffe ren t an a1 yses. Chem. Soc. Mem VOL. I. D Professors Redtenbncher and Liebig -Nos. Ox of Lead in grs. Lead. Oxygen. Atomic Weight of Lead. Lead. I Oxygen. In 100 parts. 1. 6-6155 6.1410 0.4745 1294.202 92.8275 7.1725 2. 8.0450 7.4675 0.5775 1293.074 92.8222 7.1778 3. 13.1465 12.2045 0.9420 1295.695 92- 8346 7.1 654 4. 14.1830 13*1650 1.0180 1293-222 92.8224 7.1 776 5.14.4870 13.4480 1.0390 1294.315 92.8201 7.1779 6. 14.6260 13.5775 1.0485 1294.946 92.8314 7-1686 92.8277 7.1723 '(These results which range about between 1293 and 1296 appear to prove that the atomic weight of lead lies between those two numbers. The mean of these experiments differs so little from the number arrived at in my former ones namely 1294.489 that I consider it unnecessary to alter the latter. '' If the atomic weight of hydrogen is 12.5 then the atomic weight of lead supposing it to be a multiple of that number is exactly either 1287'5 or 1300; anti if either of these nurn- bers be the true one it appears to me that my results must have oscillated about one of them instead of which they as we see oscillate about a number which lies precisely midway between the above-named." It may therefore be concluded that the fact of an atomic number being a multiple of the equivalent of hydrogen is no proof of its exactness.There are other means of controlling and estimating anew the atomic weight of carbon. The direct method viz. that of burning a known quantity of pure carbon and ascertaining the quantity of carbonic acid formed is but little fitted for the solution of the point in question since a complex appara- tus is required for collecting the gas a circumstance which lessens the dependence to be placed in such determinations. If indeed it be remembered that even in operating on several grammes of carbon the variations generally amount to from 8 to 10 millegrammes it will be evident that a complex appa- ratus offers no security for absolute accuracy.We have therefore selected a different method; an ordinary one it is true but which has been hitherto generally acknowledged to be the most certain and the most free from error in analytical chemistry. We can for instance estitnate with great certainty the atomic weights of many organic compoimds namely nu-merous organic acids by determining the proportions in which via the Atomic Weight of Carbon. they combine with oxide of silver or what is the same thing with metallic silver. These organic acids contain several atoms ofcarbon combined with oxygen and hydrogeii in cer- tain proportions which can be ascertained with great fiicility.It is evident that if the fhriniike of these acids are known with certainty we obtain the suni of the weights of the atonis of carbon by subtracting tlie sum of the atoms of oxygen and hydrogen which they coiitaiii from the atomic weights of their compounds as accurately determined by means of their silver salts. The sum of the ntorns of carbon thus ascer- tained must if the fol-merly received number for carbon be correct be a multiple of it by a whole number or it must in- dicate how far that number digers from the true one. There is no substance the atoniic weight of which we believe to be knowii with greater certainty and more precisely determined than that of silver ; the continued and important applications of it by Gay-Lussac in his assay of silver in the wet way; indeed we may say every one of liis experinients on that sub-ject is a fresh proof of its correctness.With respect to the atomic weight of hydrogen there is strong reason for thinking it to be rather less than was for-merly supposed. In the three last analyses of water by Rer- zelius and Dulong the following numbers were obtained :-1. 2. 3. Oxygen ...... EiS*942 88'809 88'954 Hydrogen ... 11*058 119191 11.046 1 oo'oco 1oo*ooo 100'000 Siipposing the atomic weight of hydi*ogen to be 6*%%8 then tlie limits of error lie between the niimtiers 6.3055 and 6.2085. lhe difference between these numbers is 0*0570 which would either increase the atomic weight of carbon from 76*437 to 76.534 or reduce it to 76'340.If we take the mean which is 6'2398 for hydrogen then the limits of error in the determination of the atotn of carbon fall in the secoriil decinial place. Such variations result as we know froin errors of observation. The method which we have selected enables us to' estimate the atomic weight of carbon in the condition in which it is contained in organic compouiids ; and it requires only three weighings:-first that of the vessel in which the salt is burned ; secontlly that of the silver salt; and thirdly that of the residual silver. In these three weighiiigs no apparatus is changed and they take place in one and the same porcelain vessel of which the weight is constant. The height of the D2 Professors Redtenbacher atid Liebig barometer and the proportion of humidity in the atmosphere exert no influence on this experiment and the silver which remains behind is not hygroscopic.The only precaution in these experiments to which the greatest attention must be directed is of course the rigid purity of the salt and consequently the entire absence of all hygroscopic water. It is at all tinies a difficult task to obtain a cheniical com-pound in a state of absolute purity ; to do this in our experi- ments was however very important as even the most minute admixture of a foreign substance must increase the found weight of the atom ot'carbon. We were soon convincecl that there are but few silver salts available in determinations of this kind ; most of them are ob-tained in the form ofcaseous or pulverulent precipitates which enter irito combination with a part of the precipitant.The quantity of foreign matter which adheres to these precipitates is so small that it does not generally render the estimations of atomic weights incorrect but as before observed we are here obliged to avoid every source of fallacy. We selected from those silver salts which are perfectly crystalline which retain no water when dried at the ordinary temperature which are not hygroscopic and which (and this is a character of great importance) do not sputter when heated. The salts em-ployed should moreover leave behind no carburet of silver after calcination. There are as stated above but few silver salts which are not liable to one or other of these sources of error.The cyaiiide of silver for instalice is easily obtained in R pure state by precipitating the nitrate of that metal by nieans of hydrocyariic acid; it can even be obtained in large shining tables by allowing to cool slowly a hot mixture of hytfro-cyanic witty with a dilute ammoniacal solution of silver; care- fully washing the crystals thus obtained with solution of ammonia and drying them at 120' C. By the latter treat- ment and even at the ordinary temperature a11 the ammonia is got rid of and the crystals become opake milk-white with- out suEering any other change; they are nevertheless in practice hot fitted to be employed in our experiment for they do not appear to lie entirely deconiposed by heat. W'hen the cyanide of' silver is first heated it melts without evolving any gas ; by increasing the temperature cyanogen is given OR and a basic cyanide is formed; at a certein point beyond this flame is developed nitrogen is then evolved the flame being at the same time as it were extinguished; and fused carburet of' silver of a dull white colour remains be- on klle Aioinic Weight of Ca?-bon.hind from which the carbon cannot be expelled by subse-quent calcination. It is true the carbon burns at the surface of the carburet leaving a stratum of pure silver but this pro- tects the inner part from the contact of oxygen; and when this residue is dissolved in dilute nitric acid a net-work of pure carbon remains. The behaviour of the benzoate of silver is very similar to that of the cyanide ; it is easily obtained perfectly pure in beautiful shining crystals which are not hygroscopic ; when this salt to the amount of 7 to 12 grammes is heated it melts and is decomposed ; but even after being kept at a red heat for twelve hours a very corisiderable quantity of carbon is found in the residue of silver.The oxalate of silver appeared at first to be the most appli- cable of any in these determinations but it is almost impos- sible to obtain it anhydrous besides which when heated in large niasses it tleflagrates in the same manner as the fiilrni- iiating mercury. We coiild it is true ascertain its compo- sition by decomposing it by mealis of liytlrochlotic acid but we consider it important to bring no foreign element into these determinations.In the following experiuients the ucetate the tartrate the racematc arid the nztllnte of silver were employed. Acetic acid owing to its volatility is easiiy obtained quite p,ure. We prepared it by decomposing some brilliantly white sugar of' lead which had been frequently recrystallized in the usual manner by iiieans of sulphuric acid. The acetic acid thus obtained which was free fiom sulphurous acid was once more rectified over hinoxide of manganese in excess. The pure acid was then partly saturated with ammonia and precipitated hy nitrate of silver in the warm. A shining white precipitate was obtained possessing the form of small laniintz liaving a silvery lustre ; this was perfectly washed on a filter dissolved in hot water the sofution filtered and left to cool in a glass .vessel when at the bottom at the surface and on the sides broad shining needles of acetate of silver of an inch in length were formed; these were again washed with pure water dried in the air finely powdered in an agate mortar and exposed to a stream of dry air at 103' c.,until the weight remaiiied unaltered.In each indivitlual analysis the weighed salt was once more lieated in r? water-bath for an hour and then allowed to cool under a bell-glass with concentrated sulphuric acid ; after which it was again weighed. It never occurred in our expe- riments that the weight WNS perceptibly altered by this treat- ment ; this precaution was nevertheless uniformly adopted.22 Professors Redtenbacher and Liebig The weighings as well as the burniiigs were conducted in a thin crucible of Meissner porcelain which was covered by a platinum lid. All our experiments were fortunately per- formed with the sanie crucible the weight of which therefore was controlled whenever weighings were niade. The calcination of the acetate of silver proceeds very easily without either swelling up or spirting. The salt at first becomes gray and on cautiously heating acetic acid distils off and then the salt assumes a brown colour; at length when the odour of the acid is no longer observable there remains a gray skeleton of silver which retains the form of the salt burnt. If the heat be now increasecl and the lid raised so as to admit a current of air a visible glowing is observed througliout the whole mass and there remains a spongy mass of shining white metallic silver.After cooling the crucible with the silver is weighed heated to redriess anew weighed agaiii and so on until riot the slightest change of weight is exhibited. The absence of car- buret of silver was always particularly demonstrated by dis- solving the silver in dilute nitric acid. The weighings were effected with a balance which indi- cated quite distinctly half a niillegrarrime even when loaded with 20 gramrnes. The weights (made by Oerthing of Berlin) were carefully compared previously to employment and were fouiid to exhihit no appreciable variation in their subdivisioiis. Lastly we adopted the precaution of condiicting one-half of the experiments with iiewly prepared salt by which means the fact that the numbers yielded by salts prepared by diG fererit operations agree is rendered very obvious.The tartrate of silver is not easily obtained in a crystnlline form. When the nitrate of silver *is precipitated in the cold by a solution of pure Rochelle salt from which by the addi-tion of a little nitric acid the weak alkaline reaction which it generally possesses has been removed a caseous and not a crystalline precipitate is formed. On the other hand if the precipitation is effected by mixing boiling hot and dilute solu- tions the liquid becomes brownish but not turbid and 011 cooling metallic silver in brown larnin~e falls down. Again when a dilute solution of nitrate of silver is heated to from soo to 85O C.and to this a hot concentrated solution of the tartrate of potass and soda is added a precipitate falls which by agitating at first disappears ; if the addition of the tartrate of potass and soda be discoiitinued as soon 3s the precipitate is permanent and is not redissolveJ fine scales of the tartrate of silver separate on cooling which after being well washed and dried are very white and have a metallic lustre resem- on the Atonaic Weight @*Carbon. bling that of polished silver. In this process the liquid must always contain a slight excess of the nitrate of silver. The pure tartrate of silver was dried and its silver deter- mined by means of calcination observing the same rules of precaution as in the case of the acetate.By gently healing the salt pyrotartaric and carbonic acids distil off and there remaim without spirting or swelling a spongy mass of bright metallic silver which when washed with water yielded to it no trace of alkali Of four determinations which we made two were with salts prepared by different operations; that em- ployed in the fifth was prepared with very special care by a gentleman in the laboratory at Giessen in the course of his investigation on the constitiitioii of orpnic acids and with a view to discover if possible some difference between the atomic weights of the tartaric and racemic acids. For the preparation of the racemate of silver very pure racemic acid was half neutralized by atnmonia the resulting sparintrl -.Y soluble acidulous salt was washeci with water redissolved in water containing ammonia and again thrown down by means of nitric acid.The acid raceniate of ammonia thus obtained was brilliantly white and perfectly pure. This was eniployed in the preparation of crystallized racemate of silver exactly in the manner described for the tartrate of that metal. These two salts do not differ from one another in appearance but the racemate is less soluble in hot water than the tartrate. We prepared the inalate of silver by means of the acid malate of lime and nitrate of silver. The acid inalate of lime is by virtue of its very unequal solubility in hot anti cold water easily obtained perfectly pure. Nitrate of silver is mixed with a warm solution of this acid malate when imme- diately granular crystalline very heavy precipitate falls.c? Since after frequently washing this silver salt with water the fluid still contained traces of lime the whole precipitate was dissolved in dilute nitric acid and to this solution ammonia was added drop by drop taking care that free acid should always be present in excess. The malate of silver is in this case free from lime and ammonia and is after continued washing quite pure. The malate of silver is decomposed when heated; it fuses at the same time evolving furnaric acid carbonic acid and water and there remains behind a porous cake of silver which is free from carbon. The following are the results of our experiments repre- sented in a tabular form.24 - Professors Redteiibacher and L.iebig In 100 Parts. Nos Atom of Carbon. - ACETATE OF SILVER. 1. 4.8735 3.1490 64.615 69.396 30,604 2091.790 302.745 75.686 2. 7.5870 4.9030 64.624 69.402 30598 2091.504 302.458 75.615 3. 6.4520 4.6950 64,623 69.405 30595 2091.511 302,465 75.616 4. 5.7905 4.74 I 5 64.614 69.395 30-605 2091.804 302,758 75.689 5. 4-1000 2.6490 64.610 69.390 30.610 2091.951 302.905 75.726 48.803 18.612 64.618 I 69-399 I30601 I2091.680( 302,634 I 75.658 TARTKATE OF SILVHR. 1. 3.8400 2.2770 59.297 63.684 36.316 2279.390 302.824 75.706 2. 27597 1 -6365 59.299 63.688 36.3 12 2279.270 302.704 75.676 3. 3.2356 1.9183 59.287 63.674 36.326 2279.751 303.185 75.799 4.5.4217 3.2147 59.293 63.682 36318 2279.530 302964 75-74] 5. 0.9630 05710 59.393 63.681 36.319 2279505 302939 75-735 _c_-----6.220 9.6 175 59.294 63.682 36.318 2279.491 302,925 75.731 -RACEMATESILVER. OF 59.290 59.292 2.7705 .59*287 63.674 59-283 63.670 59.284 59.287 -I 5.2640 3.1210 63.676 36.324 2279.670 303.104 75.776 1. 9.2668 5.4945 63.679 36.321 2279.561 302.994 75-749 2. 36.326 3. 4.6730 2279.751 303.184 75.796 36.330 4. 1.6320 0.9675 2279.920 303.354 75-838 36.329 6.5976 3.9113 63.671 5. 2279.890 303.325 75-83] 47,4334 16.2648 63.675 36.325 2279.711 304.145 75.786 MALATEor SILVEK. 1. 6.8730 4.2610 61.996 66.583 33.417 2180.141 303.575 75.894 2.4.2635 2.6440 62.015 66.604 33.396 2179,490 302924 75.731 3. 4.4305 2-7495 62.059 66.651 33.349 2177.951 301.385 75.346 4. 5.6490 3,5030 62.011 66.599 33.301 2179.621 303.054 75.764 5. 4.6820 2.9015 61.972 66.557 33.443 2181*0ll 304444 76.111 15.898 16059 62-009 66.597 33.403 21 79.707 303.141 75.785 It will be observed on first sight with respect to the pro- portion of oxide and of acid in each particular salt that our results yield the same number up to the third and in many cases to the fourth figure; and in our opinion a better selec- tion of salts could scarcely be made than that which was adopted for the proportion of oxygen in these four salts is just as unequal as that of the hydrogen; hence if an error had been occasioned by the hydrogen it could not possibly escape observation.In the acetic malic raceniic and lartnvic acids the oxygen is as the numbers 3 4 5 and the hydrogen as 4 6. on the Atontic Weight of Cnrboii. 25 With such coincidence as is exhibited in our analyses the existence of any foreign admixtiire ill these salts which could have incrensed the atomic weight of carllon cannot be sup-posed. We have however still another direct proof of their correctness viz. in the results which Berzelius obtained in his analyses of the tartrate and of the racemate of lead. These were as follows :-Tartrate of Lead. In 100 Parts. Oxide of Lead. Oxide of Lead. Acid. 1.25449 62.7245 37.2755 1.25434 62.7170 37.21330 I 4.I 2.8873 1.25522 1.81212 62.7610 62.7618 37.2390 37.2382 1 Mean1 5-8873 5.57617 1-62-7431 1 37.2569 1 NOS. Atomic Weight Sum of Four Atomic Weight of Salt. Atoms ofcarbon. of Carbon. ---c__ 1. 2223.191 303.743 75.936 2. 2223.460 304,012 76.003 3. 2221.904 302.456 75-614 4. 2221-S71 3020423 75.606 /Mean2222.531 303.082 75.771 Atomic Weights 7 Acetate of silver. . 28.803 18.612 2091.680 75.658 Tartrate . . . . . . . 16.220 9.6175 2279.491 75.731 Racemate . . . . . 27.4334 16.2648 2279.711 75-786 Malate . . . . . . . . 25.898 16.0590 21 79-707 75.785 Clrem.SOC.Mem. VOL. I. E Professors Redtenbachei and Liebig If we compare our experiments separately with one another that is to say the atomic weight of carbon as deduced from the one salt with that from the others we observe that the nunibers obtained in the analyses of the same salt agree niore perfectly with one another than do the mean numbers result- ing from the analyses of the different silver salts.If the experiments themselves be assumed to be perfectly exact this discrepancy must from the very nature of things result from some cause. This puse can be noother than the difference between the specific gravities of the different salts. They were weighed not in vacua but in air and in the pro- portion of their unequal densities they must displace unequal volumes of air. All these salts in the above weighings must lose weight and those which are specifically lighter more than the specifically heavier salts.Dr. Clark at the meeting of the British Association held at Birmingham in 1539 called attention to the influence which these relations exert on deter- minations by weight and corrected the experiments of Berze-lius accordingly. It is clear that in weighing of from one to two grammes of substance these differences will not affect the relation of numbers but when 20 or more grammes are weighed the correction ought not to be neglected. Such a correction must result from a knowledgeof the spe- cific gravities of salts. We determined those of the four salts analysed by us by taking a known weight of the salt in a saturated solution rind comparing the specific gravity of this liquid with that of pure water.3'1281 gr. acetate of silver displaced 1 gr. = 1 c. c. water at 15' C. Rut 1 c. c. of air at that temperature weighs 0*00123gr. (log. 0*0905137-2); 28*800gr. acetate of silver displaces therefore 0.0113 gr. atmospheric air. These 28*803 gr. of salt weigh consequently 28.814 gr. but the weight was estimated by means of a brass weight of 28*803 gr. which having the sp. gr. 7*S displaced 0'00455 gr. of air ;that is to say it lost that weight in air. The above 28%14 gr. of acetate of silver weighed therefore 28*8098gr. and the 18.612 gr. of metallic silver which remains behind after the calcination weighed only 18.61 13 granimes. According to these corrections 28*8098 gr. of the silver salt yield 18.6119 gr. of metallic silver.If we correct in this manner the atomic weights of the tar- trate racemate and nialate of silver the specific gravities of which are in vacuu respectively =3'4321 3'77.52 and 4*0016 we obtain the following results :- on the Atomic Wez'gAt of Ccirbon. salt. - Silver. - Atom of Carbon. Difference from the mean. Acetate of silver.. 28'8098 18.6113 75.804 -0.050 Tartrate of silver . Racemate of silver 16.223 27.438 9.6171 16.2641 75.861 + 0-007 75.938 + 0.054 Mdate of silver. .. 25.9019 16.0596 75.843 -0.011 The discrepancies in the atomic numbers for carbon lie therefore in the fourth figure or what is the same thing in the second decimal place. The atomic weight of carbon is therefore 759854. If we multiply the atomic weight of carbon as here given viz.75.854 by 1'1026 the specific gravity of oxygen we ob-tain as the hypothetical weight of' a volirme of carbon vapour 0,83636; and if to this we add 2*20520 the weight of 2 volumes of oxygen and divide the slim of these by 2 we obtain the number 1.521 for the specific gravity of carbonic acid. The numbers which have been found for the specific gra- vity of carbonic acid by means of the direct weighing of the gas are- Sp. gr. of carb. acid. Calculated at.weight. By Biot and Arago . . . . . . . 1.519 75.590 By Berzelius and Dulong . . . . 1.524 76-437 Calculated f'rom our own analyses 1.521 75*854 We consider it as a further proof of the correctness of the atomic weight of carbon as determined by us that our result lies intermediate between those of the observations of four such distinguished experimenters; and indeed all doubt inust be dissipated when we reflect that with our number the differ- ences observed in organic analyses are legitimately accounted for *.* Extract of a letter from Berzelitis to Professor Wohler :-<' April 2,1541. '' Baron Wrede is engaged with experiments in reference to the specific gravity of gases. He has devised peculiar methods of obtaining a balloon of gas in a piire state which supersede those employed by Dulong and myself. The weights of carbonic acid gas as hitherto determined by him nearly agree with those of Dalong and myself. He has found however that the spe- cific gravity of that gas is not the same under unequal pressures but that it diminishes with the decreased pressure until one-third of an atmosphere; below tliis point it is constant.Its specific gravity at the ordinary pressure E2

ISSN:0094-2405    

DOI:10.1039/MP8410100009

出版商:RSC    

年代:1841

数据来源: RSC

摘要:

IV. On Malic Acid and the Changes widergone by its Salts at Ph. D. High Temperatwes. By ROBERTHAGEN Read June 1 1841. AFTER the publication of Mr. Graham’s observation that phosphoric acid in its different states possesses the pro- perty of combining with one with two and with three atonis of base respectively it was discovered by Liebig that the same law holds good in part with many orgnnic acids; some of these acids requiring two and some three atoms of base to form neutral salts. The hydrates of each acid contain a corresponding number of atoms of basic water which cannot be removed without the decomposition of the acids them- selves. These chemists showed that though a salt of any acid with magnesia or with oxides isomorphous with it pos- sessed the power of combining with a potash salt of the same acid and forming a double salt such as the sulphate of mag-nesia and potash that is not ground for doubling the atomic weight of the acid or for viewing it as bibasic.They proved at the same time that a monobasic acid is incapable of forming a double salt with two isomorphous bases. The proportion of base which unites with a poly-basic acid is constant generally either two or three atoms. In the memoir on organic acids hy Liebig here alluded to he had made it iiot improbable that malic acid is bibasic. At his suggestion 1have made several analyses of its various salts which form the subject of this paper. Malic acid was first discovered hy Scheele in the juice of the apple; it was again discovered by Donovan in the juice of several plants and described by him RS a new acid.The identity of the acid of Donovan with nialic acid was proved by Braconnot. This acid has been most fully described by Liebig. It has also been partially examined by Pelouze Braconnot and Richardson. The malic acid used in the present investigations was pre-pared from the expressed juice of the berries of the Sorbus occupuria or Service tree in the following manner. The ex- pressed juice was mixed in a copper pan with fine!y divided is therefore somewhat too high and it contains more than one volunie of oxygen ;thus it is clear that the atomic weight of carbon as calculated from this is also too high That calciilated from his specific gravity at the pressure of one-third of an atmosphtre is 75-7.He has 1syet however only made three weighings which he considers as little more than intro- ductory experiments of practice. I shall be present tomorrow at the fourth determination.” Lh. Robert Hagen on Mdic Acid and levignted hydrate of lime care being taken not to satu-rate the fluid completely but to allow it to remain sensibly sour. Being placed on the fire it was made to boil for some hours during which time it gave off a peculiar pungent vapour which strongly affects the eyes. By degrees neutral malate of lime precipitates and may be removed with a ladle. By continued boiling more of the salt is obtained. When no more fhlls the vessel is removed from the fire arid allowed to cool when a little more is precipitated.We must take care in the beginning not to saturate the expressed juice en- tirely with lime or so much colouring matter falls with the malate of lime as to render the acid impure. The neutral malate of lime thus obtained is dissolved in dilute nitric acid (1 part acid to 10 of water) filtered and evaporated; upon cooling acid malate of lime crystallizes out in perfectly colour-less crystals. It must be well washed with cold water again dissolved in boiling water and precipitated by acetate of lead. The lead salt is decomposed by sulpliuretteti hydrogen and the malic acid obtained pure by evaporation. Malic acid forms with bases two neutral salts one of which becomes anhydrous when dried at loo3C. while the other still retains water at that temperature.It possesses decided bibasic properties and the hitherto receiwd atomic weight is necessarily doubled. The following salts have been examined :-MALATES OF LIME. a. Neutral anhydrous Mulate of Lime. C,H,O,+ ZCnO or M2uau. This salt is obtained by saturating a solution of malic acid with liine water. It is a crystalline powder perfectly insoluble hot and cold water. 0.489gramme of this salt gave 0.319 sulphate of lime or 32*1S8 per ceut. lime. This gives for the atomic weight of the salt the number 2212.40. Calculated. Found. 1 equivalent of Malic Acid 1461.39 2 equivalents of Lime . . . 712.04 67.24 32-76 67.81 32.18 b. Neutral hydrated Malate of Lime. -M ~CaO+5aq. M 2 Ca 0+ 4 aq. ( loooC.) If acid malate of lime is saturated with potash soda or ammonia and the solution evaporated at a gentle tempera- ture we obtain instead of it double salt malate of lime with 5 equivalents of water in hard shining crystals.When heated 30 Dr. Robert Hagen on Malic Acid. to loooC. this salt is converted into a porcellanous mass and is found to have lost one atom of water. At 150' C. it becomes quite anhydroiis. Of the salt in its first state of hydration 0*422gramme dried at the temperature of the atmo-sphere gave 0-2655 sulphate of lime or 26*113per cent. lime which makes the atomic weight of the salt 2725.0 and gives the following composition :-Calculated. Found. 1 eq. Malic Acid 1461.39 533.44 2 ... Lime . . . 712-04 26*03 26*113 5 ...Water . . 562*40 20*53 -I__. 2735.83 100*00 Of the salt dried at 100' :-(1). 0'6 135 grarrime gave 0.4045 sulphate of lime = 27*383 per cent. lime; and consequently the atomic weight 2600*0. (2). 0.3660 gramme gave sulph. lime 0.241 or 27-344 per cent lime. (3). 0.335 salt gave 0.353 sulphate lime and consequently the atomic weight 2598%. These give- Calculated. Found. 1. 2. 3. I Malic acid 1961.39 56.71 2 Lime . ; . 712.04 27.14 27.38 27-39 27.40 4 Water. . . 449.92 17.15 2623'85 The previous analyses of the lime salt dried without heat shows the necessity of doubling the atomic weight of the acid as otherwise we should be obliged to give it the formula C4H2O4Ca 0 + 2; aq. ; which is at variance with the atomic theory.ACIDMALATE OF LIME &f Ca 0H*0 + 6 aq. This salt is obtained when neutral malate of lime is dis- solved in nitric acid. It crystallizes in large transparent octa- hedrons. Dried at 100' C. it loses water and is converted into a viscid stringy mass. 0-706 salt gave 0*2345sulphate of lime or 13*794per cent. lime ; atomic weight 2585'8. Calculated. Found. 1 atom Malic acid 1461039 56*10 1 atom Lime . . . 356.02 13'67 13'79 7 Water . . . 787'56 30*23 2604.77 Dr. Robert Hagen on MnZic Acid. Richardson and Merydorf concluded the formula of this salt to be aCa 0 H20 + 8 aq. MALATES OF MAGNESIA. a. Neutral hydrated Malate of Magnesia. -M 2MgO + 10aq M 2 MgO + Zaq (IOO°C.). This salt is obtained by boiling magnesia in a solution of malic acid and crystallizing.It loses 8 atoms of water by 100' c. 0*5505 salt gave 0*2708sulphate of magnesia equivalent to 16.713 per cent. of magnesia; and makes the atomic weight 3091*4. Calculated. Found. 1 eq. Mslic acid 2 ... Magnesia.. 10 ... Water. . . 1124*8 146139 ,516"iO 16.66 47.09 36*55 16-713 3102.89 Of the salt dried at 100' C. 0.466 gRve 0*109 sulphate of magnesk equivalent to 23.390' per cent. magnesia. Calculated. Found. 1 at. filalic acid 1461.39 66'34 2 ... Magnesia . 516*70 23'45 23.39 2 ... 'Water . . 224.96 10'51 2209*05 This salt was also analysed by Professor Liebig with the same result. -b. Neutral anhydrous Malate of Magnesia. M 2 Mg 0. This salt is obtained by precipitating a saturated solution of the former salt (a.)with alcohol and drying at 100' C.0*344salt gave 0*0935magnesia equivalent to 26'945 per cent. ; atomic weight 1906*88. Calculated. Found. 1 atom &lic acid 2461.39 73%3 2 atoms Magnesia 5 16-70 26.12 26*94 1978'09 ACID MALATE OF MAGNESIA.-Mg 0 H20 + 3 aq M Mg 0H20 + aq (100'). Obtained by dividing and saturating one half of the malic acid with carbonate of magnesia and evaporating to crystal- 32 Dr. Robert Hagen on Malic Acid lization. It ioses 2 atoms of water by 1000C. ; at a higher temperature it melts. 1.1755 salt gave 0-1405 magnesia equivalent to 11*952 per cent.; and for the atomic weight 2161*.5. Calculated. Found. 1 atom Malic acid 1461039 6$*36 I ...Magnesia "LS*35 11*91 11.952 4 atoms Water ... 449.91 20.74 21 Gg466 Of the salt dried at 100' C. 0.698 gave 0-0795magnesia or 13.294 per cent.; atomic weight 1943.0. Calculated. Found. 1 eq. Malic acid 1461.39 75'147 1 ... &Iagnesia 258.35 I W85 13*294 2 ... water . . 224.96 1 1 *.56S ~ ~~ 1944-70 MALATES OF ZINC. a.Neutral Salt. --M 2ZO+6aq &I 2 2 0 + -(1000 C.). Is prepared by digesting carbonate of zinc with malic acid at a temperature not above 3OoC. Dried at looo C. it be-comes anhydrous. Of this salt O*4570 gave 0'2935 sulphate of zinc or 32.179 oxide of zinc making the atomic weight 3127%; the calcu- lated one being 3142.77. 0.695 of the salt dried at 100' C. gave 0.566 sulphate of zinc or 40'302 oxide of zinc; making the atomic weight 2463.6; the calculated is 2467.6.ACIDMALATE OF ZINC. a.2 0H 0+ 2aq. Prepared by adding excess of malic acid to the neutral salt. 0.190 of this salt gave 0.082 sulphate of zinc or 21*343 per cent. of oxide of zinc; the atomic weight deduced from which is 2351-7. The coniposition of the salt is therefore -CalcuI ated. Found. 1 eq. Maiic acid . 1461*4 63'480 1 ... Oxide of zinc 5039 21.861 21'349 3 ... Water . . 337*4 14*659 2302*0 Braconnot analysed this salt with the same results. Dr. Robert Hagen on Ma& Acid. BASIC OF ZINC. MALATE If malic acid is long boiled with excess of carbonate of zinc there falls down a sandy powder; of this salt dried at IOOO (1.) 0.3935 gave 0.178 or 44-66 per cent.of oxide of zinc ; atomic weight 22595. (2.) 0.255 gave 0.224 sulphate of zinc or 44.015 per cent. of oxide of zinc ; atomic weighl 2286.8. (I.) 0'474 burnt with oxide of copper gave O*lOf5water and 0*329carbonic acid. (2.) 0.5510 gave water 0'1335 and 0.3835 carbonic acid. This salt is therefore composed of Calculated. Found. 12 at. Carbon . . . 917.22 20.19 19'191 19'24 9 ... Hydrogen. . 112.32 2.47 2.52 2.69 15 ... Oxygen. . . 1500*00 33.03 33'62 84.04 4 ... Oxide of zinc 2012.9 44.31 44-66 44'015 4542*4$ Heated to 100' C. it lost 4 atoms of water; and 0*420 gave 0*411 sulphate of zinc or 49'052 per cent. oxide of zinc; atomic weight 205Z09. 0.4225 gave 0'0715 water and 0'334 carbonic acid which gives the formula C12 H5 0" + 4 2 0.This salt however is then essentially altered part of its malic acid being converted into fumaric acid as will be shown in the sequel. L Acrn MALATE OF COPPEE. M Cu 0H20 + 2 aq -M Cu 0 H20 (100' C.). Prepared by dissolving hydrated oxide of copper in malic acid and evaporating at a temperature of 30' to 40' C. as a sinall blue crystalline body. 0*690of this salt gave 0.149 oxide or 21.521 per cent. of oxide of copper; atomic weight 2302*17. The composition calculated from this is as follows :-Calculated. I Found. 1 atom Malic acid . . . . 1461'39 63.69 1 ... Oxide ofcopper 3 atoms Water . . . . . 495'70 337*44 21.60 14.71 21'821 2294.53 Dried at 100' it loses 2 atoms of water and its atomic weight becomes 2069.57.~ MALATE OF SILVER.M 2 Ag 0. 0*2877salt gave 0-1777 silver or 66.339 per cent. of'oxide of' silver. Hence Chtwt.Soc. Mem VOL I F Dr. Eobert Hagen or&Malic Acid. Calculated. Found. 1 eq. Malic acid. . . 1461039 33.48 33-66 2 ... Oxide of silver 29W21 66.52 66.33 4361060 MALATE OF BARYTES.M 2 Ba 0 + 2 aq -M 2 BaO (~oo'C.). A solution of malic acid is ssturated with barytes water and evaporated at a very moderate temperature. The salt found crystallizes At 30' C. it loses one atom of water; at 100' C. it becomes quite anhydrous. Of the salt 0'5575 dried at the ordinary temperature gave 0*452 sulphate of baryta or 53'207 per cent. of barytes; which makes the atomic weight 3956*8 the calculated one being 3600.10.The salt dried by 30' C. gave 54'426 per cent. barytes. That dried at 100' C. is composed of 1 atom of malic acid and 2 atonis of barytes. L MALATE M 2 St 0 + 3 acj OF STRONTIAN. -M 2 St 0 f 2 aq (10o"C.). FUMARATE OF ZTHYL. OF OXIDE This ether is formed whenever malic acid is brought into contact with muriatic ether. Malic acid also when long mixed with absolute alcohol or with strong fuming hydro- chloric acid is converted into fumaric acid. This combination or fumaric Ether is heavier than water and has a grateful odour like that of fruit. It is slightly soluble in water and is therefore better separated from mu- riatic ether when mixed with the latter by distillation than by means of water.By potash fumaric aether is converted into alcoho1 and the fumarate of potash. Kept long in con- tact with ammonia it is converted into f'umaramide. Purified by being distilled over chloride of calcium 0.3515 ether gave 0*268 water and 0.669 carbonic acid. Hence Calculated. Found. 8 atoms Carbon . . 61 1'48 56*29 55'803 6 4 ... ... Hydrogen Oxygen.. 74%7 400*00 6.89 36'82 6.97 37-22 1086% C4H 02,N H2. FUMARAMIDE. This amide is obtained when funiarie ether is left a long time in contact with an excess of caustic ammonia. Its forma-tion is quite analogous to that ofoxarriideand the other coin- Dr. Robert Bagen OH Mutic Acid. pounds of amide. In cold water and absolute alcohol it is quite insoluble. It is soluble in boiling water and again precipitates as the water cools.Left long in contact with water it is completely converted into. fumarate of ammonia. Ammonia is disengaged by the fixed alkalies and a fumarate formed. By distillation it is decomposed into ammonia; a white body probably maleinic acid and a residue of charcoal are left. 0.426 of funiaramide gave 0'1335 water and 0'2780 car-bonic acid. By a qualitative determination of the nitrogen the latter was found to be to the carbonic acid in volume as 1 to 4. Carbon . . . . 42.37 Hydrogen . . . 5.53 Nitrogen . . . 24-53 Oxygen . . . . 27-77 100-00 This gives-Calculated. 4 atoms Carbon . . . . 305'74 42.46 s ... Hydrogen . . . 37'11.4 5.19 1 ... Nitrogen . . . 197-04 24*59 2 ... Oxygen .. . . 200*00 27-76 720-22 1OO*OO MALATES AT HIGHTEMPERATURES. If malates of the earths or alkalies are kept for some time at a temperature varying eorn 250' to 300' C. they are changed into fumarates water being the only other product. The changes produced are best observed in the following manner. The f'umarate produced is dissolved in as small a quantity of boiling water as possible and a small excess of nitric acid is added to it. The fumaric acid crystallizes fi-om the solution in its peculiar form possessing all the properties ascribed to it by Pelouze. I have prepared its silver salt to identify it with certainty. 0.2726 acid gave 0*0585water and 0.4115 carbonic acid. This gives the following formula for its coni- position :-Calculated.Found. 4 atoms Carbon. . -305*74 91-84 91-73 ct 4 ... ... Hydrogen 24*95 Oxygen . . 400*00 3'4 1 54.75 3.60 54.683 730.69 0'373.5 of the silver salt gave 0*320.5chloride of silver or F2 Dr. Ure on Pyroz-ylic Spirit. 69-422 oxide of silver; and 0.4270 gave W029 water and 0.224 carbonic acid. 4 atoms Carbon . . . 305.74 Calculated. 14.77 Found 14-50 3 atoms Oxygen . . . . 300*00 1 atom Hydrogen . . . 12-48 14.49 0'60 15.31 0.75 1 atom Oxide of silver 1451*6 70.14 69.42 2069-82 This remarkable change of malic acid saits into those of faniaric acid appears to me to bear a strong anabgy to the formation of the pyro-and metsphosphates but this is as yet not sufficiently proved by experiment. 1 have kept a satu-rated solution of fumaric acid at a boiling temperature for several days without the slightest change in it.And I have also kept a like solutim in a tube hermetically sealed for a considerable time at it temperature of 250° under a pressure therefore of nearly 15 atmospheres without its being altered in any of its properties. Hence fumaric acid does not appear to he reconvertible into malic acid.

ISSN:0094-2405    

DOI:10.1039/MP8410100028

出版商:RSC    

年代:1841

数据来源: RSC

摘要:

V. Table of the successive Strengths af Pyl-ozglii S'iiz.it9 COP responthkg to its successive Specfie Gravities wilh some In -trodtictory Observntioiis. By ANDREW UHE,M.D. F.R.S &* Read June 1 1841. HAVING been professionally employed by an eminent manufacturing chemist about eighteen months ago in experimental researches upon the above spirit the Aolzgeist of the Germans 1 found it necessary to construct the following table in order to ascertain the commercial value ofthe article at various densities. The principd use of wood-spirit as extracted by distilration from p~~rolignoiis acid OF from liquid pyrolignite of lime is for dissolving shell-lac and sancfarac into a varnish for stiffening the bodies of hats and rendering them impervious to water.Hats imbued with this varnish exhale in the hot apartments where the process is conducted the va- pours of the wood-spirit very copiously and thereby occasion a painful irritation to the eyes of the workmen. Some kinds of the spirit are much more iiijurious to the eyes and the health than others even when they have all been rectified to apparently the same pitch of purity and strength by the same operatioris. Ohe purpose of my researches was to cliseover Dr. Ure on Pyroxylic Spirit. the causes of these variations which affect the comfort of the operatives and another was to discover the causes of the variations in the solvent qualities of wood-spirit of the same strength by the hydrometer. Having hitherto but partially succeeded in the attainment of these two objects I shall not occupy the time of the Society at present with an account of the experiments made with that view but shall reserve them for a future communication.The researches of Berzelius Gmelin Weidmann Schwei- tzer Kane Liebig Dumas and Peligot concur to prove that the ordinary wood-spirit of commerce even in its most highly rectified state is not like spirit of wine merely an alcoholic liquor more or less diluted with water but that it consists of different compounds mingled together and very difficultly separable from each other. Wood-spirit xylite and mesite are three of these liquid compounds usually associated in pyroxylic spirit. When the conimon wood naphtha of the druggist is distilled three or four times from pulverized un-slaked quicklime by the heat of a water-bath the oily impu-rities and water are got rid of and an anhydrous fluid is obtained which is not liable to become brown on exposure to light like the ordinary wood naphtha and which does not become turbid or milky when mixed with water.This puri-fied spirit however still acts 3s painfully almost as the ori- ginal cruder article upon the eyes of the hatters as I ascer-tained by trial. One mode of separating mood-spirit froin xylite and mesite is founded upon the property possessed by wood-spirit of forming a compoiind with chloride of calcium not decomposable at the heat of boiling ~ater while similar coinpourids with xylite and mesite are decomposable at that temperature.I did not find that pyroxylic spirit was essen-tially improved as to its employment in the arts by being rectified by distillation from its combination with chloride of calcium. Methol is the name which has been given to the oil formed by the action of sulphuric acid upon wood-spirit xylite and mesite; and I believe the same oil is generated by the simple combustion of pyroxylic spirit ;for I have observed that when the pyroxylic spirit which has been treated with both quick- lime and chloride of calcium is burned in a platinum capsule till fully one-half be consumed the residuum becomes oily and opalescent. The spirit used for the construction of the following table was purified by distillation from pulverized quicklime arid was drawn over with the heat of a water-bath at such a tem-perature that its specific gravity at 60' was O9S136.When Mr. R. C. Canlpbell on the Fewocyanides. the specific gravity becomes 0.847 by the dissipation of the lighter spirit the boiling point is 145' Fahr. 1 believe that a usefiil criterion of the nature of pyroxylic spirit would be obtained by comparing its boiling temperatures at different degrees of density. To this point I shall also direct my further investigations. The temperature of the pyroxylic spirit when the specific gravities were taken was exactly 60' Fahr. @c. Grav Spirit per cent. )ver proof o Excise scale Qec. Grav Spirit per cent. Over proof 01 Excise scale. 08136 100.00 0821U 98-00 64.10 0.9032 68.50 13.1 08256 96.1 1 61.10 0.9060 67.56 11.4 08320 0.8384 9434 92-22 58.00 55.50 0.9070? 0.9116J 66.66 65-00 9.37 10 08418 9090 52-50 0.9154 63.30 4.80 08470 89.30 49.70 0.9184 61.73 2.10 0.85 14 08564 08596 87-72 86.20 84.75 47-40 44.60 42.20 09218 0.9242 60.24 58.82 Under proof.0.6 2.5 08642 8333 39.90 09266 57.73 4.0 0 8674 82.00 37-10 09296 56-18 7-00 0871 2 8064 35.00 0 9344 53-70 11.00 0.8742 79.36 32.70 0.9386 5 1-54 15-30 08784 78.13 30.00 0.94 14 50.00 17.80 0.8820 77.00 27.90 0.9448 47.62 20.80 08842 75.76 26.00 0.9484 46.00 25-10 08876 74-63 24.36 09518 43.48 28-80 08918 73.53 22.20 0.9540 4 1.66 31.90 0.8930 72.46 20.60 0-9564 40.00 34-20 0.8950 71-43 18.30 0.9584 38.46 35-60 0.8984 70.42 16.60 09600 37.11 38.1 0.9008 69.44 15.3 0.9620 55.71 40.6

ISSN:0094-2405    

DOI:10.1039/MP8410100036

出版商:RSC    

年代:1841

数据来源: RSC

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Mr. R. C. Canlpbell on the Ferrocyanides. Vl. 018 the Ferrocynnides. By R. CORBETTCAMPBELL. Communicated by Dr CLARK Read June 1 1841. IT’is well known that the yellow prussiate of potash heated by itself in close vessels is decomposed into cyanide of potassium carburet of iron and nitrogen gas. I have observed that heated in contact with the air the products of the de-composition are very different. The cyanide of potassium takes oxygen from the air and is thereby converted into cya- nate of potash while the cyanide of iron is decomposed con- verting the iron into an oxide. The absorption of oxygen is caused by the presence of the cyanide of iron for cyanide of Mr. R. C. Campbell on the Zerrocyanidcs. potassium heated by itself in contact with the air does not become changed into cyanate of potash.I believe that a process for cyanate of potash may be founded on the above observation preferable to the common one with oxide of mariganese; for it has been proved that this oxide is not essential in the process and it not unfrequently happens that a large quantity of the cyanide ofpotassium is converted into carbonate of potash. Sometimes also a little manganese dis- solves along with the cyanate. For the preparation of this salt then without the use of manganese the powdered aiid dried prussiate of potash is heated almost to redness in a flat iron vessel with constant stirring of the melted mass. Some ammonia is evolved which results from the action of the moisture of the air for the substance itself contains no hydrogen.The melted mass should be taken out with an iron spacula allowed to cool reduced to powder and again fused; becat.de the melting cyanate of potash is apt to protect little bits of the yellow prussiate frorn the action of the air. If the heating be pro- perly conducted not a particle of cyanide of potassium will be formed. The cyanate of potash is dissolved out with hot alcohol filtered arid crystallized. The uadecomposed prus-siate of potash remains undissolved. The double sait of ferroprussiate of potash and lime acts under heat exactly like the ferroprussiate of potash itself. Well dried and set on fire it continues to burn until the alkaline and earthy cyanides are converted into cyanates and the iron into oxide.The reason that the double salt con- tinues to burn is to be foilrid in the porous state of the mass which offers no obstacle to the free access of air; whereas the yellow prussiate alone fuses and prevents the progress of the combustion. The ferrocyanide of ziiic which always contains some ferro-prussiate of potash in chemical combination likewise con- tiiiues to burn and affords cyanate of potash and the oxides of the metals. When the double salt of potash and lime is heated in the air as above mentioned and then dissolved in water the solu- tion possesses the remarkable property of becoming pink in the ~~11’s rays and again becoming colourless in darkness. Neither cyanate of lime nor cyanate of potash together or singly or mixed with prussiate of potash show this reaction.It is hence probable that this solution owes the above-men- tioned property to the admixture of some foreign substance present probably in a very small quantity. All attempts to isolate any such substance were fruitless. Mr. R. C. Campbell 012 the Servocyanides. As the shade of colour in the above solution is exactly that ofa solution of permanganate of potash the solution and the substances Gsed were tested for manganese. They contained none. The reactions of this solution too stand in contradiction with some of those of the permanganates. The presence of fer- rocyanide ofpotassium is essential to the production of the pink in the sun’s rays but the action of the same salt on perman- ganate of potash is first to reduce it to the green manganate and by further addition of the prussiate to oxide of rnanga-nese.As the prussiate of potash of commerce often contains traces of sulphocyanide of potassium the experiments were repeated with prussiate of potash that had been washed with hot alcohol and by this mearis all sulphocyanide removed; but no difference was observed in the result. It is further clear that this salt even if it were present in the prussiate of potash could take no part in the above-men- tioned reaction for it gives no precipitate with a lime salt with or without the presence of prussiate of potash. An alkaline state of the liquid is essential to the production of the pink in the sun’s rays ; so is likewise the presence of a ferro-cyanide.If a solution of nitrate of copper be added to a solution of the heated double salt till all ferrocyanide be removed and then the excess of copper precipitated by car- bonate of potash the solution will have lost entirely the pro- perty of becoming coloured in the sun’s rays but will recovei-it on the addition of a few drops of a solution of yellow prus- siate of potash. The air exercises no influence on these changes ;they take place equally distinctly in closed vessels. A temperature of 120’ Fahr. destroys the colour but on cooling and re-exposure to the sun’s rays the colour again appears. By evaporation in the rays Qf the sun a pink salt is obtained. The presence of cyanate of potash is not essen- tial to the production of the coloiir ; if miiriatic acid be added to the soliltion until all cyanic acid be destroyed or removed and then supersaturated with alkali the solution possesses the colouring property as strong as before.Another proof that cyanate of potash is not essential is that the double salt of ferroprussiate of lime and potash heated in closed vessels and dissolved in water shows likewise the same reaction although containing no cyanate of potash. I have already stated that the investigation undertaken with the view of isolating the colouring substance in these experiments was without success ;nevertheless some observa- tions were made which seem to stand in relation to this subject. Mr. R. C. Campbell on tfie Ferrocyanides.It has often been remarked that on adding an acid to the solution of the heated double salt a minute quantity of a red- dish powder is precipitated. This powder contains iron; it is decolorized by carbonate of potash but the colour is not reproduced by exposure to the sun. The solution from which this powder has been precipitated on being saturated with alkali and exposed to the sun's rays is found not to have lost the colouring property. I suspect that this red powder is the same as is observed to be Precipitated from some speci- mens of commercial prussiate of potash on the addition of strong acetic acid. Prussiate of potash is sometimes observed in commerce of a darker tint than usual and it is this variety which frequently shows the above-mentioned reaction.If a solution of cyanide of ammonium be added to a solu- tion of acetate of copper a compound of copper and cyanogen is precipitated not analogous in its composition to the cyanide from which it is precipitated. The supernatant solution be-comes pink-coloured for a few seconds. In order to see if this reaction result from the action of the free cyanogen on the cyanide of ammonium a stream of this gas was sent through a solution of the salt. It became first yellow and then red but a different red from that mentioned in the reaction with the copper salt. Professor Liebig pointed out to me another instance of a fugitive pink colour occurring in n cyanogen compound which Prof. Gmelin of Heidelberg has mentioned in his System of Chemistry.When strong nitric acid is added to pounded yellow prussiate of potash and slightly heated much cyanogen gas is evolved; when the heat is not too strongly applied neither prussic acid nor nitrous acid are remarked. The mass becomes black and is quite soluble in water if there be added to this solution first an excess of potash and then some drops of sulphuret of potassium the solution be-comes beautifully pink-coloured disappearing after the lapse of a few seconds. It differs from the pink colour observed 3s occurring in the solution of the heated double salt when exposed to the sun in its action to sulphuretted hydrogen. This gas or an alkaline sulphuret instantly destroys the colour resulting from the action of light while an alkaline sulphuret is essential to the production of the other.The pink colour of the solution to which sulphuret of potassium has been added becomes soon purple and afterwards deposits a blue substance which long kept in the solution becomes white. This blue precipitate cannol be prussian blue for it is produced in an alkaline solu-tion and is instantly decolorized by acids. It is possible that Client.SOC.Mem. VOL.I. G Mr. R. C. Campbell on the Ferrocyanides. the above pink solution owes its colour to the same substance as is present in Gregory’s solution of sulphuret of azote in caustic potash. I have brought forward these different instances of colora-tion occurring in cyanogen compounds because they seem to point out the existence of a yet unexaniined class of prussiates.On the Acid Cyanurate of Potash. Mineral acids as well as acetic acid were found to have the power of converting the neutral cyanate of potash into the acid cyanurate. The essential circumstance in this process is that the solution of the cyanate of potash be concentrated. The process above described for making cyanate of potash by calcining in the air the yellow prussiate of potash affords a ready means of making this salt easily and in quantity. The roasted prussiate is digested with cold water filtered and muriatic acid added to the precipitated salt is dissolved in hot water and crystallized by cooling. The foregoing experiments were partly confirmed and partly originally performed in the laboratory at Giessen in 1838. This paper is the only scientific memorial of its amiable author who died about two years ago at an early age but matureenough to have endeared him to many men of science and to have indicated promise of scientific eminence. He will be most remembered by his friends for a marked recti- tude of mind combined with an iincommon ardour ; evincing itself in the warmth of kindly feelings and in the enthusiasm of scientific pursuits.-T. C.

ISSN:0094-2405    

DOI:10.1039/MP8410100038

出版商:RSC    

年代:1841

数据来源: RSC

摘要:

[ 43 1 VII. Examination qf Cetine Ethal Oils of Laurel Turpen-tine Hyssop and Assnfmtida. By Dr. JOHNSTENHOUSE. Read November 17th 1841. Cctine. CHEVREUL gave the name of Cetine to spermaceti when rendered absolutely pure. The spermaceti of commerce always contains more or less of a yellowish oil which it re- tains wit11 great tenacity and by which its rnelting point is greatly lowered. The best means of purifying spermaceti is to treat it two or three times with boiling alcohol in which however it is very slightly soluble and then to subject it to nine or ten crystallizations in aether. These solutions and crystallizations must be repeated till the temperature at which the cetine solidifies reaches 120° F. or 121' F. when it may be regarded as perfectly pure.The cetine which I subjected to analysis was prepared in the manner just described and solidifies at 121O F. The following are the results :-(I.) 0.236 gramme gave O*ci805carbonic acid and 0-2831 water. (2.) 0.3198 gramme gave 0.9223 carbonic acid and 0.378 water. (3.) 09593 gramme gave 0*7286carbonic acid and 0'3008 water. (4.) 0-2928gramme gave 0-8468carbonic acid and 0.3476 water. 1. 2. 3. 4. Carbon. . . . . . 79.72 79-74 79.53 79-96 13ydrogen . . . . 13.32 13*13 Oxygen . . . . . 6.96 7-13 13.19 75%- 13*19 6*85 100'00 100'00 1oo*oo 100'00 ~ These analyses differ considerably from that of Chevreul though I have repeated them with every attention to accuracy. Chevreul found Carbon . . . . 81.660 Hydrogen .. . 12.862 oxygen . . . . 5.578 -100'000 It is needless however at present attempting to deduce any formula from these analyses as the acids which spermaceti contains have not been accurately determined. Sperniaceti is usually supposed to corisist of margarate and oleate of ethal. From experiments I have reason to think that one of thein is mnrgwic acid but as spermaceti when distilled yields no Chem. Soc. &fern6 VOI.. I. 13 Dr. Stenhouse on Cetiiie Ethal &c. trace of sebacic acid there is every reason to conclude the other acid it contains the quantity of which is extremely small is certainly not the oleic acid. In order to ascertain how far cetine differs in composition from ordinary spermaceti I was induced to submit a portion of the latter also to analysis.The melting point of the crude spermaceti analysed was only 107' F. (1 .) 0.3279 gave 0.9499 carbonic acid and 0.8904 water. (2.) 0*349 gave 1.0065 carbonic acid. (3.) 0.3755 gave 1*0887carbonic acid and 0*4399water. 1. 2. 3. Carbon. . . . . 80*10 7974 80-16 Hydrogen . . . Oxygen . . . . 13'23 6-67 13'01 6-83 100'00 100~00 It is evident from these analyses that the composition of crude spermaceti is precisely the same with that of the purest cetine. The small quantity of oil therefore which accompa- nies the former is probably isomeric with the more solid fat. Ethal. The ethal which I analysed was prepared by saponifjring spermaceti with powdered potash. The saponification was twice repeated in order that none of the spermaceti might escape decomposition.The lime-soap was then formed by precipitation with chloride of calcium. It was dried with a gentle heat and the ethnl extracted by aether alcohol was found inadmissible as a large quantity of the lime-soap was also dis-solved by it. I also found it advantageous to mix the lime soap with a considerable quantity of pounded glass as this prevented its adhering to the sides and bottom of the vessel when heated and thus enabled the aether to act more equally on every part of the mass. The ethal first obtained was again boiled with milk of lime again extracted with aether and repeatedly crystallized. Its melting point was 119' F. (1.) 0'5307 gave 1.519 carbonic acid and 0-665 water.(2.) 0'2881 gave 0.8295 carbonic acid and 0.361 water. (3.) 0.302 gave 0*8645carbonic acid and Om383water. 1. 2. 3. Carbon . . . 79*14 79-61 79-15 Hydrogen. . 13.92 13'02 14.08 Oxygen . . . 6-94 6.47 6-77 -I___ 100*00 100~00 100~00 These analyses agree very closely with the calculated num-bers and with the analyses of Chevreul and Dumas. Dr. Stenhouse on Lawel Turpentine &c. Calculated numbers. Atoms. Per cent. Carbon ....... 32 = 79.69 Hydrogen. ..... 34 = 13-82 Oxygen ...... 2 = 6-51 Laurel Turpentine. For some years past an essential oil to which the name of Laurel has been improperly given has been imported in considerable quantities from Demerara and some other parts of South America. It has been successfuliy employed as an external application for the cure of rheumatism.It is also an excellent solvent for caoutchouc as it dissolves that substance very readily and leaves it in a firmer and less altered state than either naphtha or oil of turpentine. Its comparatively high price however IS. per oz. precludes its employment fbr this purpose. The botanical nature of the tree which pro- duces it is unknown. The Spaniards call the tree ''acaita de sassefras." I think it probable that it is a species of pine. These trees are not very abundant but the quantity of oil they contain is exceedingly great. It runs out abundantly when incisions are made near the root of the tree and it also not unfrequently exudes spontaneously. The oil as it occurs in commerce is transparent but of a slightly yellow colour owing to its containing a little resinous matter which is easily re- moved by distilling it with water.The smell of this oil reminds oiie of that of turpentine but it is much iriore agreeable and approaches more nearly that of oil of lemons; its specific gravity is 0.8646 at 56' F. Oil of laurel is accompanied with a volatile acid the quantity of which however is extremely small. When this acid is boiled with nitrate of silver the oxide is reduced to the metallic state. The acid is probably therefore the Formic. To prepare the oil for analysis it was distilled with water to remove the resin it contained and then rendered anhydrous by fused chloride of calcium. When rectified on the oil-bath it began to hoil at 301' F.but the boiling point gradaally rose to 325O I?. It was then transparent and colourless. The first portion that distilled over was set aside but the second and third which contained nearly an ounce each were sepa- rately collected and subjected to analysis with oxide of copper. (1.) 0.2677 gramme boiling at 301" I?. gave 0.857 carbonic acid and 0.2'79 water. (2.) 0-2839 gramme boiling at 32.5' F. gave 0,9062 car-bonic acid and 099.56 water. HS) Dr. Stenhouse 012 Oils #Hyssop 4.c. 1. 2; Calculated numbers. A toms. Carbon. . . . . 88.51 88.29 88*46 = 5 Hydrogen. . . 11-57 11.57 11-54 = 4 100*08 99*83 100*00 It is evident from these analyses that oil of laurel consists of two or more isomeric oils belonging to the numerous tribe of carburetted hydrogens of which oil of turpentine is the type containing carbon and hydrogen in the proportion of 5 to 4.The action of the reagents on oil of laurel is so similar to that on oil of turpentine as to render details unnecessary. The reason which has induced me to change the name of oil of laurel to that of laurel turpentine is that there are two oils of laurel already one fixed and the other volatile with which it might otherwise be easily confounded. Oil OfHyssop. The essential oil of hyssop is easily obtained by the usual process of distilling the plant with water. The quantity which it yields is pretty considerable. The oil has the smell ofthe plant and its taste like that of the other essential oils is very pungent.When fresh it is transparent and colourless but when kept some time especially if the air is not carefully ex- cluded it becomes yellowish owing to the formation of a small quantity of resin. Oil of hyssop is lighter than water and quite neutral; its boiling point is not at all fixed; it be- gins to boil at 288' F. but the boiling gradually rises till it reaches 325O soon after which it begins to pass over coloured it is evidently a mixture of several oils. In order to deter- mine this more certainly the anhydrous oil was rectified and the product of its distillation at different temperatures collected separately and subjected to analysis. The following are the results :-1.) 0.289 gramme boiling at 288' F. gave 0.8794 carbonic acid and 0*2875 water.(2.) 0*3022gramme boiling at 299O F. gave 0'8885 car-bonic acid and 0'298 water. (3.) 052338 gramme boiling at 335' F. gave 0.8243 car-bonic acid and 0'2671 water. 1. 2. 3. Carbon. .. . . 84*13 81-29 80.31 Hydrogen. .. 11.05 10.95 10.45 Oxygen.. ... 4*82 7-76 9-24 100*00 1oo*oo 100'00 It will at once be perceived from these results that the por- Dr. Stenhouse on Oils of Hyssop Assafmlida 4.c. 41 tion of the oil richest in carbon and hydrogen distils over at a comparatively low temperature and that as the quantity of oxygen in the oil increases its boiling point rises. This is what usually takes place with oils which consist of a mixture of,&carburetted hydrogen and more or less oxygenated oils.I was induced therefore to try if these different oils could be separated by treating them with fused potash-the method so successfully employed by Messrs. Gerhardt and Cahours with oil of cumin and which promises to be extremely useful in the investigation of this class of bodies. The oil of hyssop was dropped upon the potash through a capillary opening in the tubes of a retort. As soon as the oil came in contact with the melted potash the greater portion of it was converted into a brownish resin but a part of it passed into the receiver. This portion was again subjected to the action of the potash when still more of it was converted into resin. What di-stilled over was considerably different in taste and smell tiom ordinary oil of hyssop.When subjected to analysis 0'3047 gramme gave 0,955 carbonic acid and 0'3 13 water = Carbon. ..... 86-65 Hydrogen. .... 11'41 Oxygen. ..... 1-94 100-00 It is evident therefore that I did not succeed in converting oil of hyssop into a pure carburetted hydrogen though the quantity of the oxygenated oil was considerably diminished. Oil of Assafatida . It is to this oil that asafetida owes its highly offensive smell. The quantity of oil which the resin yields varies ac- cording to its freshness. A pound of the resin generally yields about one-third of an ounce of oil which is obtained by distilla- tion with water in the usual way. It is advisable to mix the resin with pounded glass as this prevents the resin from ad- hering to the bottom of the retort and both hinders it from burning and diminishes the violence of the succussions with which the distillation would otherwise be attended.The oil has usually a slightly yellowish tint its specific gravity is 0*9428at 60' F. ;its taste is first mild and then acrid. When exposed for some time to the air it oxidizes and a resinous matter forms in it. In order to prepare it for analysis the oil which had been twice distilled with water to remove all the resin was rectified over chloride of calcium on the oil-bath. Its boiling point is by no means constant; it began to boil at 325' F. and continued to rise till it reached 370' F. The re- ceiver was changed three times during the distillation,' and the Dr. Stenliouse on Oil qf Assafmtida &c.products separately collected and analysed. The presence of sulphur in oil of assafmtida was first noticed by Zeise. It dif- fers from oil of mustard by containing 110 nitrogen. The carbon and hydrogen were estimated by analysis with oxide of copper and the sulphur was determined by passing the oil in vapour over a mixture of nitre and carbonate of baryta at a red heat. The following are the results :-(1.) Analysis of 1st quantity 09967 oil boiling at 325' F. gave 0.710 carbonic acid and 0'2625 water. (2.) Analysis of 1st quantity 0.2915 gave 0.6935 carbonic acid and 0-253 water. Per cent. 0.382 oil gave 0-635 sulphate of baryta = 22-93 sulphur. 0.391 oil gave 0'639 sulphate of baryta = 22.54 sulphur. 1. 2. Carbon .. . . 66.16 65-78 Hydrogen . 9'83 9.64 Sulphuq . . -22.93 22.54 Oxygen . . 1.08 2-04 100'00 100~00 (I.) Analysis of 2nd quantity of oil boiling at 341' F. 0.2312 gave 0*523carbonic acid and 0.1967 water. (2.) Analysis of 2nd quantity 0.2728 gave 0-6177 carbonic acid and 0*2224water. (3.) Analysis of 2nd quantity 0*2889gave 0.6461 carbonic acid and 0'2447 water. 0.413 oil gave 0.601 sulphate of baryta = 20.12 per cent. sulphur. 0-421 gave 0-610 sulphate of baryta = 19*99per cent. sulphur. 1. 2. 3. Carbon. . . . . 62*54 62.60 61-83 Hydrogen. . . 945 9-05 9.4 1 Oxygen . . . . 7-89 Sulphur . . . . 20.12 8.36 19.99 1oo*oo 1oo*oo (1.) Analysis of 3rd quantity of oil boiling at 370° F. 0'3036 gave 0*6415carbonic acid and 0.2493 water.(2.) Analysis of 3rd quantity of oil 09947 gave 0*6185 carbonic acid and 0.241 3 water. 0-344 gave 0*421sulphate of baryta = 16*88 per cent. sul-phur. 0'382 gave 0.436 sulphate of baryta = 1-5.74per cent. SUE-phur. Prof. Bunsen on the Radical of the Cacodyl Series. 49 1. 2. Carbon. . . . . 58.42 58.03 Hydrogen . . . Sulphur . . . . Oxygen . . . . 9*12 16-88 15.58 9'09 15.74 17.14 100~00 1oo*oo It is evident from these results that oil of asafoetida is a mixture of various oils one or more of which consist probably only of carbon hydrogen and sulphur with other oils con- taining more or less oxygen. The less oxygenated portion is the most volatile. It is therefore unnecessary to attempt to deduce any formula fiorn these analyses.Though oil of as-safetida was twice treated with fused potash in the same man- ner as oil of hyssop the greater portion of the sulphur was removed but I could not succeed in getting rid of the whole. The greater portion of the oil was converted into a blackish resin. This resinous matter is soluble in alkali from which it is precipitated by acids. It is not in the least degree cry- stalline. The action of reagents on oil of assafcetida was as follows :-salts of silver lead and protoxide of mercury gave black precipitates. When brought in contact with peroxide of mercury heat was evolved and a part of the oxide was converted into a greenish yellow mass which was insoluble in water. A very small portion of the oil was acted on however.Corrosive sublimate immediately produced a copious flocculent white precipitate. It was insoluble in water alcohol and Ether. It was soluble in nitric acid and when boiled with solution of potash the mercury was precipitated in the state of protoxide. Oil of assafoetida does not combine with am-monia. It is very little acted on either by aqueous or alco- holic solutions of potash. Nitric acid acts on this oil with great energy and the evolution of deutoxide of azote. It is converted into a resin and on adding a salt of baryta an abundant precipitate of sulphate of baryta is obtained. Sul-h ric acid first reddens and with the assistance of heat chars i." It dissolves iodine readily but without explosion. Glssgow 14th October 1841.

ISSN:0094-2405    

DOI:10.1039/MP8410100043

出版商:RSC    

年代:1841

数据来源: RSC

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Prof. Bunsen on the Radical of the Cacodyl Series. 49 WIL. On the Radical of the Cacodyl Series of Compounds. L3y Professor BUNSEN Marbarg. of Read December 21,1841. 1. Isolation of Cacodyl. SOME of the cacodyl compounds have the remarkable pro-perty of being decomposed by metals. When sulphuret Professor Bunsen on the Iiudical of cacodyl is heated in contact with niercury in a large vessel to 200' or 300' C. the mercury becomes covered with a stra- tum of sulphuret of mercury without any apparent disen- gagement of' gas. The fluid which condenses in the vessel gives off' fumes and takes fire of itself in air if the heat has been continued long enough and the temperature sufficiently high. This process is however not available for the exhibi- tion of cacodyl as the mercury only acts upon the sulphur compound of cacodyl at a temperature at which cacodyl already begins to be decomposed.Bromide of cacodyl be- haves in the same manner; under similar circumstances a mixture of bromide of mercury and a fluid which fumes in the air is produced :-Kd Br 7 f Kd Hg ,J = XHg Br. When this mixture is boiled in water the bromide of mercury is reduced aiid bromide of cacodyl-is regenerated and giveh off with the watery vapour :-Kd 1 (Kd Br HO H 0. The last reduction alsgtakes $ace at too high a temperature for the exhibition of the radical. The isolation is most easily and perfectly effected by using a metal capable of decomposing water and forming a chloride particularly zinc iron or tin.When tin or any of the foregoing metals is added to anhy- drous chloride of cacodyl the metal is dissolved at a tempe- rature of goo to 100' C. without any evolution of gas. The solution which is at first clear becomes of a dark colour on further solution of the metal. Water separates the pure chlo- ride of tin and leaves cacodyl mixed with a trace of chloride of cncodjl behind :-&I Sn a } ={g;c** As zinc however effects the reduction of the chloride with the greatest facility and as no fiirther decomposition takes place in the chloride of zinc formed I have in my experi- ments exclusively used this metal for the isolation of' the radical. Notwithstanding that the reduction appears so easy still as it is very difficult to prevent subsequent decomposition in repeating the distillation and crystallisation of a substance which is as inflammable as the vapour of phosphorus I think it necessary to enter into fiirther details regirding the method of producing it.Very thin sheet zinc the surface of which has been pre- of the Caeodyl Series. viously cleaned with dilute sulphuric acid and afterwards well washed is cut into small pieces to be employed for this pur- pose. The chloride of cacodyl must be quite free from oxy- gen. By digesting oxide of cacodyl three times over in con- centrated hydrochloric acid a pure substance is procured which does not give off any vapour. 'This chloride milst be allowed to remain in a close vessel with chloride of calcium and caustic potash without being distilled in order to deprive it of any water it may contain and also of any excess of acid.To prevent all access of air in this operation a glass vessel of this description is employed (fig. 1.). At Fig. the opening a a stream of carbonic acid is con- ducted through the vessel with the bulb e to contain the substance to be dried. When the atmospheric air is entirely displaced both ends n and 6 are sealed. When the vessel is re-quired for use the point a is broken and at- tached by a caoutchouc tube connected to an air-pump; the point b is then broken and put under the surcace of the chloride of cacodyl; the latter is sucked up into the apparatus and then immediately closed I will call this the drying apparatus.The reduction and distillation is carried on in a somewhat similar manner in an atniosphere of carbonic acid in a closed vessel (fig. Z.) the bulb a being the distillation tube and the bulb b the receiver. Fig. 2. The whole apparatus being pre- viously filled with carbonic acid the chloride of cacodyl is sucked into the bulb n also containing the zinc. The open end of the vessel is then immediately closed with the blowpipe. It is exposed to the tem- perature of 100' C. for three hours in a water-bath. The zinc is readily dissolved without any evolution of gas and the solution becomes of a dark colour. On cooling to 50' C. large cubic crystals are formed which are redissolved by heating. These crystals are probably a combination of chloride of zinc and chloride of cacodyl.When the zinc is no longer acted upon at 103' C. the contedts of the bulbs appear converted into a dry mass of salts which upon an increase of temperature to 110° or 120° C. melts into an oily-like Professor Bunsen on the Radical liquid. After the whole apparatus is warmed the point of the receiver b is opened under cold water previously boiled. Upon the entrance of the water upon the cooling of the apparatus it is again sealed and the water is con- ducted into the distillation bulbs. After a short digestion a solution of chloride of zinc is formed the zinc in excess remaining with a clear surface and leaving the radical at the bottom as an oily liquid. This liquid is then trans-ferred into the drying apparatus aid when perfectly dry is sucked up again into the distilling apparatus and digested for a short time with clear zinc by which means a small quan- tity of chloride of zinc is formed.It is then distilled and comes over as clear as water. At a temperature of -6' C. large prismatic shining crystals are formed. After two-thirds of the solution has crystallized the remaining solution is again distilled and this is repeated three times over. The solution is finally put into a tube filled with carbonic acid. The analysis of this liquid was conducted in the usual manner with oxide of copper. The arsenic sublimed in fine crystals in the back part of the tube without the formation of any arsenical copper or any arsenical salts.The quantity of arseiiic was ascertained by weighing the tube before and after heating. The analysis gave the following results :-1. 2. Substance . . . . . . 0*620gr. 0.500 gr. Carbonic acid . . . . 0*500 0.402 Water. . -. . . . 0'306 0'200 Tube before heating. 62.681 60-670 ... after heating . 61.869 60.020 The composition of this radical is therefore Calculated. 1. 2. Carbon 4 equivalents 23-15 22.30 22.23 Hydrogen 6 Arsenic 2 ... ... 5-67 71.18 5'48 71.29 5*33 71. Loss and Oxygen . . . 0-00 0.93 1.44 100' 100. 100- The trifling difference between the quantities found and the calculated quantities arises probably from the impossibility of obtaining this compound free from oxygen. If the results obtained are reckoned in the 100 parts without taking notice of the oxygen the carbon and the hydrogen agree still closer.The quantity of arsenic on the contrary appears rather too much. The facility with which cacodyl can be separated from its compounds by simple substances renders it very of the Cacodyl Series. 53 probable that the oxide might be also reduced by means of carbon as well as hydrogen upon the application of a higher temperature. Dumas's analysis as well as my previous one of the liquor of Cadet renders this supposition nearly certain and fully explains the cause of our arriving at different results. Dumas found as I did also in my first experiments acon-stant excess of arsenic carbon and hydrogen which is ac- counted for by the impurity of the oxide of cacodyl.There was no difficulty in ascertaining the density of the vapour of the liquid as the temperature at which it is decom- posed is considerably higher than its boiling point. Substance ........ 0*2500gramme. Volume measured. ... 55-98 Cbr. Temperature ...... 200' C. Barometer ........ 328'5 lines. Column of oil ..... 38 lines. Col. of merc. at ZoooC. 44.5 lines. This gives the density of 7.101 which agrees as nearly as could be expected with the calculated density viz.-4 volumes of vapour of carbon . 3.3'71 12 ... hydrogen ..... 0-825 2 ... vapour of arsenic .10'367 14363 -2='7*281. The difference of 0.18 in the result obtained is fully ac- counted for by the tension of the mercury vapour in the ba- rometer at the temperature of ZoooC.The agreement of both the analysis and density of the va- pour with the respective calculated quantities is a matter of coiisiderable interest. Berzelius has shown that when a cer- tain density of a gaseous organics1 radical is assumed the relative condensation which the compounds of this radical present exactly agree with those of inorganic or simple ra- dicals. This circumstance has given a weight to the theory of the compound radicals which the law of substitution could not reach. But this in connexion with the phaenomena of substitutions does not advance the idea of organic radicals be- yond the limits of a hypothesis. The proof of their reality is connected with three other conditions viz. 011 their isolation on the direct formation of their compounds and on the actual agreement of the density of their simple elements with their theoretical density.All these conditions are fulfilled in regard to cacodyl it may be isolated it enters into direct combina- tions and it has the density required if the laws of condensa-tion of the inorganic elements are valid for organic bodies as may be observed by the following statement. Professor Bunsen on the Radical Cacodyl ............ 4 vol. C + 12 vol. €1 +2 vol. As= 2 vol. Kd Observed. Calculated. 7.101 7.281 Cacodyl oxide . . . 2 vol. Kd + 1 vol. 0 = 2 vol. Kd 0 7.555 7.833 Sulphuret Cacodyl2 vol. Kd + 1 vol. S = 2 vol. Kd S 7.810 8-39 Chloride Cacodyt .1 vol. Kd + 1 vol. C1= 2 vol. Kd C1 4.56 4.86 Chloride Cacodyl .3vol.KdC1+ 1vol.KdO =4vo1.3 KdCl+KdO 5-46 5.30 Cyanuret Cacodyl . 1 vol. Kd + 1 vol. Cy = 2 vol. Kd Cy 4.65 4-54. This radical possesses the following properties :-It is a clear thin highly refracting liquid very similar to oxide of cacodyl ; it has the same smell but is more inflamma- ble. A glass rod moistened with it immediately takes fire when exposed to the air its boiling point is about 170" C. At -6' C. it crystallizes in large square prisms; if the sub-stance is pure it becomes like ice. It burns in oxygen gas with a pale blue flame and forms water carbonic and arsenic acids which rise in the form ofa white smoke. If the air is not in sufficient quantity for the combustion Erytrarsin is formed and a black stinking mass of'arsenic remains In chlorine it burns with a clear flame and deposits carbon.Digested with hydro- chloric acid and metallic tin it is converted with the appear- ance of various products into erytrarsin. 'I'he same substance is produced by the action of phosphorous acid chloride of tin and other powerful reducing agents. Fuming sul-phuric acid dissolves the radical without combining with it. In the cold a quantity of sulphurous acid is evolved and on distillation it gives oRa substance with an agreeable aethereal odour which appears to be sulphate ofaetherol. 2. Formation of the Compoundsof Cucodylfrom their Radical. The relative condensation of the gaseous compounds of cacodyl and the transformations which they undergo,. give a great degree of probability to the theory of organic ra- dicals which is now rendered perfectly incontrovertible by the power of this radical to form directly the coppounds from which it was separated.The whole series of com-pounds already considered can be formed either in the di- rect or in the indirect way and the conditions under which this happens are precisely those observed with regard to the metals. The indirect action of oxygen as well as the action of most of the oxidizing agents occasions an increase of tempe-rature in the formation of both the oxide and the acid of this radical; and from the first by the action of hydracids we obtain the corresponding combinations with sulphur selenium tellurium chlorine iodine bromine and cyanogen. By the treatment of the so-formed chloride with chloride of copper chloride of platinum chloride of palladium &c.certain dou- of the Cacodyl Series. ble chlorides are formed which I intend to refer to hereafter. When the radical is dissolved in nitric acid and nitrate of silver is added a very considerable precipitate is produced in the form of regular octahedral crystals consisting of a cornbi-nation of the latter salt with oxide of cacodyl which appears to act the same part as constitutional water in salts. A solu-tion of corrosive sublimate occasions the immediate formation of an oxychloride in the form of fine silky crystals composed of 1 atom of oxide of cacodyl combined with 2 atoms of chlo-ride of mercury. Oxidizing agents are not the only bodies which act in a direct manner ; other combinations are also formed in the same way.Sulphur in small quantities is acted upon by the radical being dissolved by it and forms a clear solution- pos-sessing all the properties of sulphuret of cacodyl producing with solutions of oxides of lead and silver sulphurets of these metals and sulphuretted hydrogen with acids. Upon the ad- dition of a large quantity of sulphur a higher sulphuret is formed which is solid and soluble in aether ;from which latter solution it map be obtained in fine crystals. When to cacodyl a solution of chlorine is added its yellow colour is irnmedi- ately destroyed together with its bleaching power; chloride of cacodyl is formed which acted upon by acids gives hydro- chloric acid.All these reactions to which many more might be added of a not less striking nature prove that this radical acts the part in every instance of a simple electro-positive ele- ment and that it is infact a true oigunic metal. 3. Decomposition of the Badicnl. When the radical is distilled with anhydrous chloride of zinc it is decomposed and forms several compounds at differ- ent temperatures. In order to ascertain more precisely the nature of this decomposition pure chloride of cacodyl was digested with zinc in a distillation tube until the whole solu- tion wasconverted into a white mass of salt; the heat was then increased by means of an oil-bath to 200' C. ; a perfectly clear fluid distilled over. When at this temperature nothing further passed over the heat was increased to 220O C.and then to 260' C. It appeared to me dangerous to attempt any further decomposition by increasing the temperature ;the attempt was therefore given up at this point. After the apparatus was cool and the receiver taken off there was no perceptible smell of any gaseous product. The substance which distilled over was again sucked up into a fresh distillation tube containing zinc mid by means of a continued digestion the last traces of chlorine were separated. The di- Professor Bunsen on the Radical stillation was effected by means ot' an oil-bath. When at the temperature of 100"C. nothing more came over the receiver was separated; its contents (No. 1.) were removed into a tube filled with carbonic acid with all the precautions already mentioned and again slicked up into a fresh distillation tube and re-distilled at fiom looo to 170" C.The product (No. 2.) was put up also into tubes. The residue which remained in the distillation tube at 1'70' C. was again for the third time removed into a fresh distillation apparatus and again distilled at from 170' and ZOOo C. without leaving behind any percep- tible residue and forms No. 3. All the three distilled pro- ducts were quite tramparent ether-like very liquid and quite free from chlorine. The first scarcely took fire of itself had a strong ethereal smeI1 and remained liquid at -18' C. The two others were exceedingly inflammable and crystallized at -8' C. in large prismatic crystals like cacodpl.Tested with corrosive sublimate the first gave but little appearance of containing cacodyl; on the contrary the two last appeared to contain a considerable quantity. Analysis gave-No. 1. First Distillation. Substance .......... 0.56 1 Carbonic acid ........ 0*5875 Water ............ 0.3665 Tube before burning .... 80'261 ... after burning ..... '79.310. No. 2. Second Distillation. Substance .......... 0.5403 Carbonic acid ........ 0.5140 Water ............ 0.3145 Tube before burning .... 74.976 ... after burning ..... 74.147. No. 3. Third Distillation. Substance .......... 0.5930 ~~ Carbonic acid ........ 0'4265 Water ............ 0.2635 l'ube before burniiig .... 83.0195 ... after burning .....82*3Z'iO. These results (a repetition of which I think unnecessary as the Weighillg of the tube after burning serves as a check upon them) give the following conipositions :- of the Cacodyl Series. 57 1st distillation 2nd distillation 3rd distillation at 90" to 100" C. at 100' to 170" C. at 170" to 200" C. equiv. equiv. equiv. Carbon. . . 4 28.95 4 26.31 4 19-88 Hydrogen . 6.1 7-26 6.05 6-46 6.1 4.82 Arsenic. . . 1-3 64.31 1.7 67.15 2.55 75-50 I00.52 99.92 100523. It follows from the analysis that this radical on distillation with chloride of zinc undergoes a catalytic decomposition without the separation of arsenic dividing into two or more compounds in which the same quantity of carbon is combined with different quantities of arsenic; a circumstance of much interest as regards the theory of organic radicals.It is there- fore probable that cacodyl like arsenic is a binary radical composed of C H, and that its constituent elements are com- bined in such a manner that the compound of the cacodyl series are repeated in a similar way only of a higher order. The above-described products of decomposition undergo at a teni- perature of about 400Oto 500° C. a decomposition which I an1 in hopes from the peculiarities in the constitution of the radi- cal to direct attention to. When cacodyl or the before-men- tioned mixure of the product of decomposition is heated in a bent retort over mercury the gas of this substance is decom- posed at a temperature little exceeding the boiling point of mer-cury into metallic arsenic and a mixture of a compound of car-bon and hydrogen without the separation of a particleof carbon.This gaseous substance burns with a variegated light flame with cz very slight deposition on glass of metallic arsenic. A solution of sulphate of copper or nitrate of mercury has no action upon the gas however long it may remain in contact. With chlorine over water it takes fire like a mixture of phos- phuretted hydrogen and burns with deposition of carbon producing a red-coloured flame. Mixed with oxygen gas and inflamed by the electrical spark it explodes more powerfully than fulminating ga? and generally breaks the vessel. Eudio-metrical examination of the gas gives the following results :-1. 2. Calculated.Volume of the gas . . . . 1-t 1.5 1.5 ~~ Oxygen gas consumed . . 3.5 3.4 3.5 Carbonic acid formed. . . 2.0 2.0 2.0 These trials exactly agree with a compound in which the combination with the carburetted hydrogen in the cacodyl gives 4 volumes of vapour of carbon 12 volumes of hydrogen condensed into 6 volumes. I was at first induced to suppose that a similar decomposi- Professor Uunsen on the RndicaZ tion of cacodyl took place as in the case of cyanide of mer-cury as the action of this gas with chlorine did not agree with the action of any of the compounds from which this mixture of gases could in any nianner arise; but the uncommon con- densation the essential circumstance in this case appeared little to support this view.I have therefore continued the examination and found that the burning with chlorine arises from the presence of a small quantity of a volatilizable com- pound of arsenic which does not separate from the mixture and which is at the same time the cause of the small stain of arsenic which on burning this gas in oxygen remains on the side of the eudiometer. The true nature of this gas given out by heat from cncodyl is shown hy the action of fuming sulphuric acid. This absorbs nearly one-third and leaves behind an inodorous gas burning pale blue which is not al- tered by chlorine in the dark in the direct rays of the sun however as Melsens has shown of the gas of the acetates and of marshes it is condensed into oily camphor-like odorous bodies in the state of small white radiating crystals.From a eiidiometrical analysis of this gns it appeared to be pure marsh gas. I found From the volume examined ...19-2 Oxygen consumed ........41.1 Carbonic acid formed .......21 *8 There can therefore be no doubt that the carburetted hy-drogen C H, formed on the decomposition of cacodyl at a high temperature is not separated as such but that there are formed under these circumstances two volumes of marsh gas and one volume of olefiant gas viz. C H As = {:t,", C H The examination of the gas not absorbed by the sulphuric acid confirms this view of the question ;as one volume and a half of the pure gaseous mixture which contains one volume of olefiant gas and two volumes (C H,j of ninrsh gas must in fact upon burning with three and a half volumes of oxygen produce two volumes of carbonic acid.Whilst the absence of arsenietted hydrogen and firnee hy-drogen decidedly proves that the first is not to be considered as a constituent element of cacodyl; the conclusion may be drawn at the same time from these appearances of decom-position that if the radical C PI cat] exist independently it is most unstdde and is decomposed much below a red heat. OJ the Cacvdyl Series. Among the products of the decomposition of cacodyl there is one substance which I have mentioned several times aiid to which I have given the arbitrary name of erytmrsin I shall now consider this substance as it is in close connexion with the foregoing substances.I have not hitherto succeeded in obtaining any quantity of this remarkable substance. It is formed as a secondary product in the formation of chloride of cacodyl sometimes in a great and sometimes in a small quan- tity. It is also deposited upon the distillation of oxide of ca- codyl with water. Upon conducting the vapour of cacodyl or oxide of cacodyl through tubes slightly heated this sub-stance is produced in large quantities by an imperfect com- bustion; but obtained in this manner it is always contami- nated with arsenic from which it is impossible to separate it. The substance next made use of in preparing it was obtained in the following manner. About 100 gramnies of oxide of cacodyl was added to con- centrated hydrochloric acid ; chloride of cacodyl was formed and a red flocculent precipitate fell which after distillation of the chloride remains behind in the retort.The precipitate became during the distillation of a thick consistence which increased and became of a darker colour with the appearance of finely divided red oxide of‘iron. After six or eight lloilings with absolute alcohol the substarice was obtained quite pure and free from chlorine. It is necessary during this boiling to protect it from the air and to dry the substance in a vacuum with sulphiiric acid as otherwise it is liable to absorb oxygen slowly. Prepared in this n~aniier erytrarsin is of a steel blue shading into dark red free from smell and without the least appearance of crystallization. It is easily ruliberl down into a red powder which absorbs oxygen slowly from the air with the appearance of the formation of arsenious acid as it be- comes covered with a white powder This decomposition does riot take place until after exposure for several weeks.It is not soluble in alcohol =ether or water-even caiistic potash does not act upon it. In concentrated and not fuming nitric acid it is soluble with decomposition. Red fuming acid occa- sions oxidation with inflammation. Heated in the air it barns with an ash-coloured arseiiical flame without leaving any residue. Heated in a glass tube it gives out vapours smelling of cacodyl and deposits carbon arsenious acid arid a ring of arsenic. The quantity produced from 100 grammes of oxide amounted to a little above 0*,5graninie.From the want of a sufficient quantity of this substance I have only been able to make one analysis which I however trust is sufi-cient :is every precaution was taken to ensure its accuracy. Chrni 3’ec. Mcn7. VOL. I. 1 60 Professor Bunsen on the Radical of the Cacodyl Series. 0'394 gr. of the dried substance was burned with oxide of copper and gave O*1253 carbonic acid and 0'0'74 water. ?'he arsenic was ascertained from the contents of the burning tube. These were dissolved in nitric acid the solution diluted with water and partly precipitated by carbonate of soda. The solution filtered from the copper was perfectly free from arsenic. The precipitate dissolved in hydrochloric acid to which sulphuret of soda was added also produced no preci- pitate of arsenic The filtered solution gave after being boiled with sulphurous acid in the usual manner 0.5191 sul-phuret of arsenic ; of which 0-6333 acted upon by nitric acid gave 0.0528 sulphur and 2.1566 of sulphate of' barytes.The following are the results :-Calculated. Found. c,. . . 305.76 8.73 8.58 H . . 74*88 2.14 2-08 As . . 2820*24 80*56 8 1*56 0,. . . 300*00 8.57 7-78 3500*88 1oo*oo 100~00 The difference of one per cent. in the arsenic found is ac-counted for from a small quantity of sulphuret of copper which was contained in the sulphuret of arsenic which on account of its small amount could not be ascertained. The atomic weight of this substance I have not been able to ascer-tain in a direct way as it does not enter into any direct com- bination; but the probability is from the relation it holds to cacodyl and to oxide of cacodyl that that stated above is correct.I have therefore shown that the radical of the ca- codyl series is converted at a temperature approaching to redness into marsh gas and oil gas which gases map be con-sidered as decomposing products of a non-isolated carburetted hydrogen C Hq. From what precedes it also follows that of three atoms of oxide of cacodyl two atoms are decomposed in the manner described while one atom of erytrarsin is left behind :-3 atoms ofoxide of Cacodyl C, H, AsG0 2 atoms of C H . . . C8 HI =4CH2+4CH C €3 AsGO The rational constitution of this coinpound can only be con- jectured.As cacodyl in combination with oxygen undergoes the same decomposition at a higher temperature as in an un-combined state it follows that erytrarsin may be considered as the oxide of a ternary radical which can be distinguished from cacodyl only by its containing three times as much Mr. warington on Chromic hid in F701iaicArrangements. 6 1 arsenic. The complete examination of such a substance would be attended with great danger and many difficulties.

ISSN:0094-2405    

DOI:10.1039/MP8410100049

出版商:RSC    

年代:1841

数据来源: RSC

摘要:

Mr. warington on Chromic hid in F701iaicArrangements. 6 1 IX. On the employment of Chromic Acid as an Agent in VoZ-ESP. taic Arrangements. By R. WARINCTON Read December 7 1841. a paper ‘‘On the Action of Chromic Acid upon Silver,” published in the Philosophical Magazine for December 1837 which action was effected by means of a mixture of bichromate of potash in solution and sulphuric acid I concluded by stating that in a future communication I hoped to consider the action of the same agents on other metallic bodies. The investiga- tion has been resumed when my engagements permitted and a great variety of interesting facts on this subject collected; but many analyses will still be necessary to render the subject complete before the whole results can be submitted to the scientific world.On making some new experiments some time since with the mixture of bichromate of potash and siilphiiric acid re- ferred to I was led to believe that it would form a valuable and powerful agent in voltaic arrangements from possessing the following advantages over every other liquid hitherto em- ployed for the same purpose namely the high degree of energy with which it acts upon certain metals the facility with which it is decomposed by deoxidizing agents as hydrogen gas and numerous others with the circumstance that in all these actions of oxidation no gaseous matter is evolved. My first endeavour was to substitute this mixed fluid for the nitric acid in the powerful arrangement of Professor Grove so as if possible to obviate the inconveniences arising during the action of that battery without diminishing the splendid effects produced by it.In doing this it was abso-lutely necessary from the nature of the materials to be em- ployed to modify to a certain extent the details of the con-struction of the battery retaining the metallic elements unal- tered but enlarging considerably the cell appropriated for the nitric acid. Now as the dilute sulphuric acid in the zinc cell of the battery remains the same in both cases it will be only necessary to show by the constitution of the nitric acid and the bichrornate of potash the relative value of these two oxi-dizing agents in terms of’the quantities of the available oxygen they contain such oxygen combining with the hydrogen eli-12 62 Mr.Warington on Chromic Acid in Voltaic Arrangements. cited by the action of the dilute sulphuric acid on the zinc element. Liquid nitric acid of 1.48 sp. gr. is composed of 74 parts by weight of real acid and 26 of water and these '74parts contain 32.9 of oxygen and 41.1 of binoxide of nitrogen which latter body is given off in a gaseous state as soon as the undecomposed nitric acid has become saturated with it and assumed a deep green tint. When liberated from the solution the gas combines with the oxygen of the air generating the nitrous and hyponitric acids the red noxious vapnurs which render the use of this form of battery so inconveniect. There must I imagine be also a considerable loss of power from this evolution of gaseous matter.I am not aware to what extent the decomposition of the nitric acid can be carried in Grove's battery for after the action has been going on about five hours an effect of endosmosis commences between the cells through the pores of the biscuit earthenware and the amal- gamated zinc plates are attacked with rapidity and quickly destroyed. Not expecting such an occurrence I had left a small battery in action 011 one occasion through the night and found in the morning to my great annoyance that the whole of the zincs were destroyed and the arrangement all fixed together. Bichromate of potash is composed of 2 equivalents of chro-mic acid or 104 parts by weight and 4705 of potash and these 104 parts contain 80 of the green oxide of chromium and 24 of oxygen.Consequently to obtain the same quan-tity of available oxygen as we have in the 100 parts of nitric acid supposing the decomposition of these to be complete we shall require 206.9 of bichromate; and to convert this into the double sulphate of chromium and potash or chrome alum 275.8 of concentrated sulphuric acid will be necessary. These proportions of materials are requisite as it is the strong affi-nities leading to the forniation of chrome alum which give rise to the energetic oxidizing action of this mixture. A number of experiments were tried to ascertain whether the action of a battery excited by the acid element described would be sustained and continuous and the results have fully established that it is so.In the action of such a battery nu gaseous matter is given off the oxygen of the chromic acid combining with the hydrogen from the zinc cell to form water as is the case where nitric acid is employed. And as the de- oxidized chromic acid or the oxide of'chromium formed com-bines with the sulphuric acid and potash immediately as it is produced no injurious effect can arise from diffusion between the cells; the whole process goes on steadily and without in- Prof. Bunsen on Cucodyl Compounds containing Platinum. 63 termission until either the siilphuric acid in the zinc cell is saturated with the oxide of zinc or the whole of the chromic acid of the bichrorriate is deoxidized. Various other arrangements in which bichromate of potash is used mixed with sulphuric muriatic nitric and acetic acids with the usual and also with different metallic elements are under investigation ;and the results obtained with their com- parison with other batteries will be laid before the Society at an early period.

ISSN:0094-2405    

DOI:10.1039/MP8410100061

出版商:RSC    

年代:1841

数据来源: RSC

摘要:

Prof. Bunsen on Cucodyl Compounds containing Platinum. 63 X. On a new Class of Cncodyl Compounds containing Pla-tinum. BY ProJessor BUNSEN ofMarBurg*. Read December 7 1841. a former paper I have endeavoured to prove from the IN,umerous instances of substitution presented by nlcarsin that this substance contains a ternary radical composed of arsenic united to a carbo-hydrogen (C H + As,) and en- tering into composition with elementary bodies like a metal in a manner not hitherto observed. This opinion has been confirmed by niy subsequent experiments and may be consi- dered of considerable importance in the question of compound radicals. The chloride of this radical is reduced by those metals which decompose water at a temperature not exceed- ing that of boiling water; the free radical separating in the form of a clear aethereal fluid which oxidates in the air with more rapidity than potassium and produces two degrees of oxidation by it5 combustion namely an acid and an oxide both of which can be again reduced by deoxidizing agents.The analogy between cacodyl and the metals extends still further ; for that radical unites directly with the non-metallic elements forming substances of the same nature as are pro- duced when hydracids combine with the elements of metallic oxides water being produced. It will be seen from what has been said that this substance bears a greater resemblance than most other compound bodies to ammonia. Vnder this impression I tried the action of clzloride of platinum on it and have been fortunate in ob- taining a class of conipounds analogous in composition to those of Gros and Reiset ; supposing the ammonia in the latter replaced b_v cacodyl.The results obtained tend to throw a new light on the relations in which the organic bases or alka- loids stand towards the simple oxides of metals. Translated from the German MS.of the author by Dr. T.G. Tilley. 64 Prof. Bunsen on Cacodyl Compounds containing Platinum. Chloride of Cacoplatyl. By mixing an alcoholic solution of chloride of platinum with a similar solution of chloride of cacodyl a precipitate of a reddish-brown colour is obtained which when washed with alcohol and rediiced to powder becomes yellowish-red and is inodorous. When this powder is heated it melts into a clear yellow gummy mass gives off hydrochloric acid and vapours smelling of chloride of cacodyl and leaves behind a gray-co-loured arseniuret of platinum.Both the chlorides of‘ pla-tinum and cacodyl are indicated in this conipound by reagents. ShouCd this compound be analogous to the chloride of caco-dgl its composition would be Pt C1 + Kd C1. This body, however could not be analysed for it is so easily decomposed as not to be of uniform composition. If the precipitate in question be boiled with water a yellowish solution is formed alcargen being generated at the same time and the solution on cooling deposits white needle-shaped crystals. This sub- stance may be named chloride of cacuplatyl and fiom this name the others will be derived.To obtain the chloride of cacoplatyl in larger quantities and in a more easy manner an aqueous solution of chloride of platinum is boiled with chlo- ride of cacodyl. The precipitate which falls first of a brown colour is changed by boiling into a wine-yellow colour. The precipitation of the chloride of cacoplatyl commences even during the boiling and by cooling still more is deposited. The mother liquid contains nothing except a little alcargen (or perhaps a true salt of cacodylic acid and oxide of platinum). The crystals are collected on a filter and purified by redis- solving. This compound possesses the following properties :-it crystallizes from a hot solution in long sharp needles which are beautifully formed is inodorous its taste disgustingly arsenious.It is soluble in hot alcohol and water more sparingly so in these liquids cold. When heated it becomes yellow then brown and without melting takes fire and burns like tinder,. giving off vapours smelling of arsenic and leaving behind fusible arseniuret of platinum. Sulphuric acid by depriving the compound of water turns it yellow. Hydro-chloric acid has no action. In amriionia it is soluble in all proportions ; by evaporating the solution imperf’ect crystals are formed which are insoluble in alcohol. Iodide of potas-sium produces in the solutions of chloride of cacoplatyl a yellow precipitate which dissolves of a reddish-brown colour in ammonia. With bromide of potassium a compound cry- stallizing in long silky needles is formed.Cyanide of potas- sium gives a yellowish white precipitate. By nitrate of silver Prof. Bunsen on Cacodyl Compounds containing Platinum. 65 the chloride of silver is thrown down without destroying the neutrality of the solution. The elementary analysis of the chloride of cacoplatyl dried at 110' C. was made by means of oxide of copper in a com- bustion tube the free space left in the tube being filled with tarnings of copper". In a second analysis chromate of lead was used; the results were the same:- 1. 2. Substance . . . . . 1.440 1-0194 Carbonic acid . . 0.494 0.3480 \Vater. . . . . . . 0956 0'2475 The chlorine was estimated by heating the compound to red-ness with caustic lime. 1.0873 gramme of substance gave 0.580 chloride of silver or 0-0225 silver ; by direct precipi- tation from the solution by nitrate of silver from 0.987 of sub-stance only 0'353 chloride of silver or 0'1405 silver was ob-tained.The estimation of the platinum and arsenic is attended with some difficulty from the circumstance that chloride of cacoplatyl is not perfectly. oxidized by nitric acid. 0.850 gramnie was therefore heated in a combustion tube with a mixture of 1 part of carbonate of soda and 3 parts of chlorate of potash. The contents of the tube after digestion with water left r2 quantity of arseniuret of platinum. The solu- tion which was coloured yellow by a little of the double chlo- ride of platinum and potassium was thrown on a filter and the arsenic containing platinum again collected.This last was dissolved in aqua regia and some silicic acid derived froni the combustion tube separated. The fluid freed from silicic acid and evaporated to dryness was again dissolved in weak alcohol and gave 0*752 gramme chloride of platinum and potassium. Besides this 0*018 platinum was obtained by heating a quantity ofsulphuret formed by transmitting through the solution a stream of sulphuretted hydrogen. The fluid when filtered was made use of for obtaining the quantity of arsenic; it was freed from alcohol by boiling deoxidized by sulphurous acid and precipitated by sulphuretted hydrogen. It gave 0.458 of sulphuret of arsenic from which by oxidation with nitric acid 1*254 of sulphate of barytes was obtained. These analyses conduct to the following formula for chlo- ride of cacoplaty1:- * This precaution is necessary lest some chloride of copper be carried into the chloride of calcium tube with the watery vapour ; when metallic copper is present a basic chloride of copper is formed which is not volatile.66 Prof. Bunsen on cacodyl Compounds contaz'nz'ig Platinum. 1. 2. Carbon c . . Hydrogen H . . Arsenic As . 305'7 87-4 940-0 9'44 2.70 9*49 2.75 29-54 9-52 2.73 29.29 Platinum Pt . . 1233.3 37'98 38.34 Chlorine CI . . 442.6 13.48 13-85 13.79 Oxygen 0,. . 200.0 6.39 6-32 3209.0 1oo*oo 100'00 The agreement between the carbon hydrogen and chlorine found and the numbers obtained by calculation proves with- out doubt that the following empirical formula C H As Pt CI 0,,is correct.It appears certain that this compound con- tains an atom of water not as water of crystallization but in another form for the compound may be heated to 164O C. without decomposition. At that temperature the colour is changed to a citron yellow and an atom of water is 'given off; which however is reacquired when the substance is boiled with water. 0'9767 loses by 210' C. 0'037 and no more although the temperature is raised to 240' C. The compound con- tains therefore 3-79 per cent. of water which corresponds to 1 atom and can be replaced by Z atom of ammonia. Bromide of Cacoplu{yl. This compound is formed when a hot solution of the chlo- ride of cacoplatyl is mixed with bromide of potassium; the crystals obtained are redissolved and recrystallized twice.They possess great similarity to the chlorine combination and form small yellow needles by the quick cooling of the aqueous solution; but when the solution is allowed to cool gradually the crystals formed are large well-shaped and co- lourless. They are pretty soluble in hot but only sparingly soluble in cold water. They have a feeble acid reaction are inodorous but possess a decidedly disagreeable arsenical taste which is bitter and astringent and remains long on the palate suggesting alcarsin. At 120O C. they lose their water and become yellow. At 240' C. this compound begins to be decomposed becoming gray at that temperature ; and when the heat is increased to 246" C. it melts into a black fmtid mass.At a higher temperature it takes fire in the air and burns like tinder leaving the arseniuret of platinum in shining scales. The analysis of this compound is equally simple with that of the preceding chlorine compound and is made by combustion with oxide of copper; the anterior part of the tube being filled with copper turnings. Prof. Bunsen on Cacodyl Compounds contninhg Platinum. 67 Dried at 1003C. 1. 2. Substance . . . 0'8895 1.1347 Carbonic acid . . 0933 0'34'73 Water . . . . * . 0.190 0*0249 To estimate the quantity of the bromine 0-7145 gramme was dissolved in water precipitated by nitrate of silver and boiled some timewith nitric acid by which 0.452 bromide ofsil- ver wasobtained. This research gives the following numbers:- Carbon c4.. 305-76 Calculated. 1. 2. 8-17 8.16 8'37 Hydrogen H . . 87-36 2.33 2*39 2.41 Arsenic As . 940-08 25-10 Platinum Pt .L. 1233026 32-93 Bromine Br . . 978-30 26-15 26.56 Oxygen 0,.. 200gO0 52.34 3744-76 100*00 To determine the proportion of water in the substance 1.2534 gramme was dried at looo C. and then heated in an oil-bath at Zooo till no more weight was lost. The loss was 0°040 which is equal to 3*200per cent. It will be seen that this compound like that of chlorine contains 1 atom of water. The formula for the hydrous and anhydrous compounds respectively are Pt 0 C €3 As Br Pt 0 C H As Br. In this compound also the water can be replaced by ammonia. ?odide of Cacoplatyl. The yellow precipitate which iodide of potassium forms with chloride cf cacoplatyl is this iodide.By mixing the two solutions boiling hot and tolerably dilute the iodide separates in the form of glistening scales of a silky lustre resetnbling the iodide of lead. It possesses nearly the same degree of solubility in water as the last-named substance. The iodide differs from the other compounds of cacoplatyl in losing its whole water at 100' C.; it becomes then of a brown violet colour without melting. The brown crystals dis- solve in water forming a yellow solution which deposits cry- stals again on cooling. This compound also is inodorous and may be submitted to ;Ihigh temperature without decomposition. It is in.jured at 260' C. when the compound melts and becomes black giving off dark vapours smelling like alcarsin and lastly burns like tinder leaving the arseniuret of platinum.For the analysis of this substance it was dried and burned with oxide 68 Prof. Bunsen on Cacodyt Compounds containing Platinum of copper and copper-turnings which last prevent any error arising from iodine passing over. 1. 2. Substance. . . 1.4322 1'1 46 Carbonic acid 0*3745 0.300 water . . . . 0*2510 0*400. To estimate the iodine 0*6685of the salt dried at 100' C. was precipitated from solution by nitrate of silver the preci- pitate being afterwards boiled in nitric acid. This trial gave Cal c 11t ated. I. 2. Carbon C .. 305.76 7.22 7-23 7'24 Hydrogen €3,. . 74'88 1-77 1.95 94 Arsenic As . 940'08 22-22 Ylatinum Pt.. 1233.26 29.14 Iodine I . . 1578*28 37-29 96-58 Oxygen 0 . . 100*00 2.36 4232.62 lOO*OO Sulphate oftgze Oxide of Cacoplatyl. To prepare this compouiicl a solution of 20 parts of the chlo- ride of cacoplatpl dried at 100' C. is boiled with 12-17 parts of dried sulphate of silver till the solution is not rendered tur- bid by salts ofsilver or chlorine. The filtered fluid is evapo-rated in vacuo over sulphuric acid till crystallization begins. At this degree of concentration it trace of the chloride of' sil-ver which bad remained dissolved is precipitated. The chlo- ride of silver is separated by filtration and the solution again evaporated in vacuo and over sulphuric acid till the greater part of the salt is deposited. The salt is purified by pressing it between folds of'bibulous paper.Thus prepared it has the form of white hard crystalline grains which appear under the microscope to be prismatic. This salt is inodorous but possesses a bitter and astringent taste which after a time sug-gests a relation to the cacodyl compounds. It does not deli- quesce nor is it decomposed by contact with air. It may be heated to 160° C. without injury; a few degrees higher its colour becomes gray then black giving off vapours smelling of cacodyl and lastly it takes fire and burns like amadou leaving behind an arsenical compound containing platinum which is fusible. To ascertain the quantity of water contained in this com-pound 1*078gramme was dried for 24 hours over suiphuric acid and then again for six hours at a temperature of looo C.the loss of weight was O-GO45 gramme. By heating it for three hours longer at 140' C. it lost 0°0025gramme. It thus appears that this conipound parts with its hygroscopic water Prof. Bunsen on Cacodyl Compounds containing Platinum. 69 with difficulty. It contains no more water which can be driven offby any elevation of temperature. 1.0390 gramme of this salt dried at 140° C. burnt with chromate of lead gave 0.2395 water and 0'340 carbonic acid. 0.5491 gave 0*1290water and 0'175 carbonic acid. 1-0474 gramme dissolved and precipitated by nitrate of ba-rytes gave 0-047'46 sulphate of barytes. These determinations give the following composition :-1. 2. 9-08 Carbon c4 . . 305'7 Calculated.8.81 8'81 Hydrogen H . . 87-4 2*6G 2.56 2.61 Arsenic As . . 940.0 27.91 Platin urn Pt . . 1233.3 36-62 Oxygen 0 . . 300'0 8-91 Sulphuric acid S 0 . 501.2 14.88 15.57 The characters of the chloride of cacoplatyl are so well marked and its relations to other bodies so manifest that we cannot be in doubt for n moment as to its rational composition. One glance at its empirical formula will satisfy 11s that here as in the compounds of cacodyl the most electro-negative element chlorine can by analogy be replaced by bromine and iodine just as oxygen is replaced by sulphur. The man- ner in which this substitution takes place is not different from that which we observe in the inorganic saline compounds. The chloride of cacoplatyl treated with the iodide of potas-sium gives up its chlorine to the potassium while the iodine goes over to the other element of the formula from which the potassium Has withdrawn the chlorine.The order of affinity of chlorine iodine and bromine for the substance in question bears a perfect analogy to what we observe in the inorganic haloid salts. The iodine is here set free by chlorine and bro- mine as in these salts while bromine is removed by chlorine only. Such an agreement in relation shows a similarity in the form of the groups of the elements and indicates that here as in the inorganic haloid compounds there are two divisions in the formula one of which represents the metal the other the halogenous body or salt-radical. We can express it thus:-Pt 0 C H As + C1.The first division of this formula which I have called caco- platy] represknts a peculiar and remarkable radical forming classes of compounds possessing great interest and giving an insight into the relation in which the vegeto-alkalies stand with regard to organic radicals. As the vegeto-alkalies when heated give off ammonia so our compound gives off water and this water can be replaced by oxides of metals. If we 70 Prof. Bunsen on Cacodyl Compounds contai?zi?g Plrrtinzrm. remove this atom of water in the formula we have remaining one atom of oxide of platinum and one atom of cacodyl which will explain the forination of these compounds in the simplest manner. The rational expressions may be thus given :-For the anhydrous chlorine compound Pt 0 Ka +Cl For the hydrous ...H 0 PtOKa+ C1 For that containing ammonia .....N H Yt 0 Ka +C1 For,the oxide .............H 0 Pt 0 Ka +0 For the sulphate .......... (HOPtOKa+O) SO The nature of this composition proves that the power of inorganic acids to unite with certain organic bodies without losing their power of saturation is not alone possessed by acids but that bases have also the same property; for in the present case the oxide of platinum bears a relation to the oxide of cacodyl similar to that which sulphuric acid does to benzoic acid in sulpho-benzoic acid. In the latter the ben- zoic acid is as little indicated by reagents as the oxide of pla-tinum in the cacoplatyl; and as the double acid referred to neutralizes only one atom of base so the double base in question saturates only one atom of acid or that quantity which the quantity of oxygen in the oxide of platinum indi- cates.A comparison of this new class of compounds with that discovered by Gros and Reiset will afford another reason for admitting the constitution which has been assigned to them. Reiset has rendered certain the existence of a body composed of the elements of 1 atom water 2 atoms atnmonia and 1 atom oxide of platinum which does not lose its atom of water when it enters into combination with oxygen acids and contains precisely as cacoplatyl 2atoms of oxygen and saturates 1 atom of acid. Berzelius affirms that these salts contain the oxide of ammonium. Here ammonia is combined with the oxide of platinum as the naphthaline is in sulpho-naphtbalic acid viz.(Pt 0N H, N H,+ 0)S0,. The simple relation in which this salt stands to the caco- platy1 compound must therefore not be passed over. The latter is nothing else than such a salt in which the ammo- nium is replaced by cacodyl. Its relation to ammoniuni in the electrical series of compound radicals is like that of an electro-negativ.e metal to an electro-positive he as for in- stance iron to potassium. It cannot however be denied that while the compound of Reiset is a strong caustic base the oxide of cacoplatyl forms only salts of an acid reaction. The analogy which the vegeto-alkalies and their composith show is so great that it permits no doubt as to the identity of their Mr.E. Schunck on Lecanorin &. constitution with that of this body. It now only remains for me to show by comparison the greatness of this analogy by the.. substitution of the platinum compound by an organic oxide. Reiset's Compounds. N H3,Pt 0,N H4 + C1 H Pt Kd + GI ((320 H,) 02 N H + GI N H,,Pt 0,N H4 + I H$tKd+I (C20 H,) 02 N H4 + 1 NHa,PtO,NH,+ 0 . Hl%Kd+O ((320 H,) 02 N H4 + 0 (N Hj Pt0,N H4 + 0)S 0,. (HPt Kd + 0)S 03. (C20H,02N H + 0)S 0,. The formation of urea (a body which possesses all the pro- perties of an organic base and may be considered as a cyanate of oxide of ammonium) belongs to the same class of pli~no-mena. In that compound an oxide of cyanogen (cyanic acid) occupies the place of the oxide of platinum in Reiset's ammo- nium COIII~OU~~, and unites with ammonium to give rise to a compound radical if such it may be considered.The radical (-Cy0 N H4)which forms part ofurea is in every relation similar to cacoplatyl; the oxide of that radical or urea being of all this class of compounds that which approaches most closely to the oxide of cacoplatyl (Cy 0,N H4)+ 0=urea.

ISSN:0094-2405    

DOI:10.1039/MP8410100063

出版商:RSC    

年代:1841

数据来源: RSC