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Abstracts of papers in the “philosophical transactions”

 

作者: Henry Watts,  

 

期刊: Quarterly Journal of the Chemical Society of London  (RSC Available online 1851)
卷期: Volume 3, issue 3  

页码: 257-320

 

ISSN:1743-6893

 

年代: 1851

 

DOI:10.1039/QJ8510300257

 

出版商: RSC

 

数据来源: RSC

 

摘要:

ABSTRACTS OF PAPERS IN THE PHILOSOPHICAL TRANSACTIONS.*V BY HENRYWATTS,B.A. F.C.S. On the Diffusion of Liquids. By Professor Graham.+ Any saline or other soluble substance once liquefied and in a state of solution is evidently spread or diffused uniformly through the mass of the solvent by a spontaneous process. It has often been asked whether this process is of the nature of the diffusion of gases; but no satisfactory answer to the question appears to be obtained owing it is believed to the subject having been studied chiefly in the operations of endosmose where the action of diffusion is complicated and obscured by the imbibing power of the membrane which is peculiar for each soluble substance but no way connected with the diffusibility of the substance in water.Hence also it was not the diffusion of the salt but rather the diffusion of the solution which was generally regarded. A diffusibility like that of gases if it exists in liquids should afford means for the separation and decomposition even of unequally diffusible substances and being of a purely physical character the necessary consequence and index of density should present a scale of densities for substances in the staterof solution analogous to vapour-densities which would be new to molecular theory. 31. Gay-Lussac proceeded upon the assumed analogy of liquid to gaseous diffusion in the remarkable explanation which he suggested of the cold produced on diluting certain saline solutions namely that the molecules of the salt expand into the water like a com-pressed gas admitted into additional space.The phenomena of solubility at the same time were considered by that acute philosopher as radically different from those of chemical affinity and as the result of an attraction which is of a physical or mechanical kind. The characters indeed of these two attractions are strongly contrasted. Chemical combination is uniformly attended with the evolution of heat while solution is marked with equal 1 Phil Trans. 1850 I 1. VOL III.--NO XI 8 PROFESSOR GRAHAM constancy by the production of cold. The substances which com-bine chemically are the dissimilar while the soluble substance and its solvent are the like or analogous in composition arid properties. In the consideration of solubility attcntion is generally engrossed entirely by the quantity of salt dissolved But it is necessary to apprehend clearly another character of solution namely the degree of force with which the salt is held in solution or the intensity of the solvent attraction quite irrespective of quantity dissolved.In the two solid crystalline hydrates pyrophosphate of soda and sulphate of soda we see the same ten equivalents of water associated with both salts but obviously united with unequal degrees of force the one hydrate being persistent in dry air and the other highly eBorescent. So also in the solutions of two salts which are equally soluble in point of quantity the intensity of the attraction between the salt and the water may be very different as exemplified in the large but feeble solubility in water of such bodies as the iodide of starch or the sulphindylate of potash compared with the solubility of hydrochloric acid or of the acetate of potash which last two substances are capable of precipitating the two former by displacing them in solution.Witness also the unequal action of animal charcoal in withdrawing different salts from solution although the salts are equally soluble; and the unequal effect upon the boiling- point of water produced by dissolving in it the same weight of various salts. Besides being said to be small or great the solubility of B substance has also therefore to be described as weak or strong. The gradations of intensity observed in the solvent force are particularly referred to because the inquiry may arise how far these gradations are dependent upon unequal diffusibility ; whether indeed rapidity of diffusion is not a measure of the force in question.A number of six-ounce phials were first made use of to contain the solutions and to form what are called the Solution phials or cells. They were of the same make and selected from a large stock of the common aperture of 1.175 inch. Both the mouths and bottoms of these phials were ground flat. The mode of making an experiment and the apparatus (Fig. 1.)have already been described FIG. 1 in a paper by the author “On the Application of Liquid Diffusion to produce Decomposition.”* The characters of liquid diffusion were first ex-amined in detail in the case of chloride of sodium.(1.) Do different proportions of chloride of sodium in solution give corresponding amounts of diffused salt ? Solutions were prepared of chloride of sodium in the proportion of 100 water with 1 2 3 and 4 parts of the salt. The diffusion of all the solutions was continued * Chem. SOC. Qu. J. 111 60. ON THE DIFFUSION OF LIQUIDS. 259 for the same time eight days at the mean temperature of 52O.5 Fahr. Diffusion-product. Proportion of salt to 100 water in solution to be diffused. Xngrai ns. Ratio. 1 2-78 l* 2 5.54 1.99 3 8-37 3-01 4 11-11 400 The quantities diffused appeap therefore to be closely in pro-portion (for this salt) to the quarmtity of salt in the diffusing solution. The relation which appears in these results is dso favourabIe to the accuracy of the method of experimenting pursued.The variation from the speculative result does not in any observation exceed 1 per cent (2.) Is the quantity of salt diffused affected by temperature ? The diffusion of the same solutions of chloride of sodium was repeated at two new temperatures 39O.6 and 674 the one being above and the other below the preceding temperature. It was necessary to use artificial means to obtain the low temperature owing to the period of the season. A close box of double wdls was employed masses of ice being laid on the floor of the box and the water-jars supported on a shelf above. The water and solution were first cooled separately for twenty-four hours in the ice-box before the diffusion was commenced.It was found that the temperature could be maintained within a range of 2*or 3O for eight days. It was doubtful however whether the temperature was constantly the same to a degree or two in all the jars; and the results obtained at an artificial temperature were always less concordant and sensibly inferior in precision to observations made at the atmospheric tern-perature DIFFUSION OF CHLORIDIE OF SODIUM. Diffusion-product. Proportion of salt to 100 water. 2.63 1. 5.27 2-90 7-69 2 32 10*00 3 80 1 at 67O 3*50 I* 6.89 1.97 9-90 2.83 IJ JJ 13-60 3.89 PROFESSOR GRAHAM The proportionality in the diffusion is still well-preserved at the different temperatures. The deviations are indeed little if at all greater than might be occasioned by errors of observation.The ratio of diffmion for instance from the solutions containing 4 parts of salt is 3.80and 3.89 for the two temperatures which numbers fall little short of 4. The diffusion manifestly increases with the temperature and as far as can be determined by three observations in direct proportion to the temperature. The diffusion-product from the 4 per cent. solution increases from 10 to 13.60 grs. with a rise of temperature of 2P4 or rather more than one-third. Supposing the same pro- gression continued the diffusibility of chloride of sodium would be doubled by a rise of 84 or 85 degrees. (3). The progress of the diffusion of chloride of sodium in ex-periments of the ki12d narrated was further studied by inter- cepting the operation after it had proceeded for different periods of 2 4 6 and 8 days.The solution employed was that containing 4 parts of salt to 100 water. Two of the six-ounce phials were diffused at the sanie time for each period. Diffused in 1st two days . 3.95 grs. I 2nd 1 . . . . 3.00 , 31 3rd If 8 0 2.91 I> 4th I> . . . . . 3.26 , The diffusion appears to proceed pretty uniformly if the amount diffused in the first period of two days be excepted. Each of the phials contained at first about 108grs. of salt of which the maximum quantity diffused is 13-12 grs. in eight days or +of the whole salt. Still the diffusion must necessarily follow a diminishing progression which would be brought out by continuing the process for a longer time and appear at the earliest period in the salt of most rapid diffusion.All the experiments which follow being made like the preceding on comparatively large volumes of solution in the phial and for equally short periods of seven or eight days may be looked upon as exhibiting pretty accurately the initial diffusion of such solutions the influence of the diminishing progression being still small. The volume of water in the water-jar is also relatively so large that the experiment approaches to the condition of cliffusion into an Unlimited Atmosphere. DijTasion of various salts and other substunces.-Tn the following experiments the diffusion took place at a temperature ranging from 62O to 594 mean 60O.5 and was continued for a period of eight days; the proportion of salt in solution to be diffused being always 20 salt to 100 water or 1 to 5.The density of the solutions is added 9 ON THE DIFFUSION OF LIQUIDS. 26 1 DIFFUSION OF SOLUTIONSOF 20 SALT TO 100 WATER AT 60% POR EIGHT DAYS. Density of Anhydrous salt diffused. Name of salt. solution at 609 In grains. Means. Chloride of sodium 1.1265 58.5 Chloride of sodium. . 191265 58.87 58.68 Sulphate of magnesia . 1-185 27-42 27.42 Nitrate of soda . . . le120 52.1 Nitrate of soda . . 1.120 51-02 5 156 Sulphate of water . . 1.108 68.79 Sulphate of water . . 1 108 69.86 69.32 Crystallized cane-sugar. 1.070 26.74 26.74 Fused cane-sugar .. 1 so66 26.21 26.21 Starch-sugar (glucose) 1 *06l 26-99 26.94 Treacle of cane-sugar . 1.069 32.55 32.55 . 1.060 13.24 13-24! Gum-arabic . . Albumen. . . 1.053 3-08 3.08 The following additional ratios of diffusion were obtained from similar solutions at a somewhat lower temperature namely 48O;-chloride of sodium 100; hydrate of potash 151.93; ammonia (from a 10 per cent solution saturated with chloride of sodium to increase its density) 70 ; alcohol (saturated with chloride of sodium) 75.74; chloride of calcium 71.23; acetate of lead 45.46. Where two experiments upon the same salt are recorded in the table they are seen to correspond to within 1 part in 40 which may be considered as the limit of error in the present observations.It will be remarked that the diffusion of cane- and starch-sugar is sensibly equal and double that of gum-arabic. On the other hand the sugars have less than half the diffusibility of chloride of sodium. It is remarkable that the specifically lightest and densest solutions those of the sugars and of sulphate of magnesia approach each other closely in diffusibility. On comparing together however two sub- stances of similar constitution such as the two salts chloride of sodium and sulphate of magnesia that salt appears to be least diffusive of which the solution is densest. But the most remarkable result is the diffusion of albumen which is low out of all proportion when compared with saline bodies. The solution employed was the albumen of the egg without dilution but strained through calico and deprived of all vesicular matter.As this liquid with a density of 1.041 contained only 19-69 parts of dry matter to 100 of water the proportion diffused is increased iz= the table to that for 20 parts to correspond with the other sub- stances. In its natural alkaline state the albumen is least diffusive PROFESSOR GRAHAM but when neutralized by acetic acid a slight precipitation takes place and the liquid filters more easily. The albumen is now sensibly more dif€usive than before. Chloride of sodium appears twenty times more diffusible than albumen in the table but the disparity is really greater; for nearly one-half of the matter which diffused from the latter consisted of inorganic salts.Indeed the experiment appears to promise a delicate method of proximate analysis peculiarly adapted for animal fluids. The value of this low diffusibility in retaining the serous fluids within the blood-vessels at once suggests itself. Similar results were obtained with egg-albumen previously diluted aad well-beaten with 1 and 2 volumes of water. Nor does albumen impair the diffusion of salts dissolved together with it in the same solution although the liquid retains its viscosity. Three other substances added separately in the proportion of 5 parts to 100 of the undiluted solution of egg-albumen were found to diffuse out quite as freely from that liquid as they did from an equal volume of pure water these were chloride of sodium urea and sugar Urea proved to be a highly diffusible substance.It nearly coincided in rate with chloride of sodium. A second series of salts were diffused containing 1part of salt to 10 of water-a smaller proportion of salt which admits of the comparison of a greater variety of salts. The temperature during the period of eigbt days was remarkably uniform 600-59O. DIFFUSION OF SOLUTIONS OF 10 SALT TO 100 WATER AT 59O5. __ -_ Density of Anhydrous salt diffused. Name of salt. solution at 604 In grains. Means. -_. -.. _~_ 1 0668 32.3 Chloride of sodium . . 1.0668 32.2 32.25 Chloride of sodium. . . . . 1.0622 30.7 30.7 Nitrate of soda Chloride of potassium . . . 1.0596 40-15 40.15 1.0280 40.20 40.20 Chloride of ammonium Nitrate of potash .. . 1*0589 35.1 1.0589 36.0 35.55 Nitrate of potash . . . 1.0382 35.3 35.3 Nitrate of ammonia. . s Iodide of potassium. . 1*0673 37.0 37.0 Chloride of barium 1*0858 27.0 27.0 . 1-0576 37.18 Sulphate of water 1.0576 36.53 36435 Sulphate of water . 1.0965 15.3 sulphate of magnesia 1.0965 15.6 15.45 Sdphate of magnesia 1 *0984 15.6 Sulphate of zinc. . . . 1*0984 16.0 15.80 E(ulphateofl;inct ON THE DIFFUSION OF LIQUIDS. Before adverting to the relations in diffusibility which appear to exist between certain salts in the preceding table the results of the diffusion of the same solutions at a lower temperature may be stated. DIFFUSION OF SOLUTIONS OF 10 SALT TO 100 WATER AT 37O.5-Anhydrous salt diffused.Name of salt. In grains. Means. Chloride of sodium . . . . 22*21 Chloride of sodium . . . . 22-74! 22.47 Nitrate of soda. . . 22-53 Nitrate of soda. . . . . . 23.05 22.79 . . 31.14 31.18 Chloride of ammonium Nitrate of potash . . . . . 28-84 28.56 28.70 Nitrate of ammonia . . . 8 29.19 29.19 Iodide of potassium . . . . 28.10 28.10 Chloride of barium . . 8 21.42 21b42 Sulphate of water . . . . 31.11 Sulphate of water . . . . . 28.60 29.85 Sulphate of magnesia. . . . 13*03 Sulphate of magnesia. . . . 13-11 13*07 Sulphate of zinc . . . 11087 13.33 1260 Sulphate of zinc The near equality of the quantities diffused of certain isomorphous salts is striking at both temperatures.Chloride of potassium and chloride of ammonium give 40.15 and 40*20grs. respectively in the first table. Nitrate of potash and nitrate of ammohia 35.55 (mean) and 35.3 grs respectively in the first table and 28.70 and 29.19 Frs. in the second table. Sulphate of magnesia and sulphate of zinc 15.45 and 15% grs. (means) in the first table with 13.07 and 12.60 grs. in the second. The relation observed is the more re-markable that it is that of equal weights of the salts difised and not of atomically equivalent weights. In the salts of ammonia and potash this equality of diffusionis exhibited also notwithstanding considerable differences in density between their solutions ; the density of the solution of chloride of ammonium for instance being 1*0280,and that of chloride of potassium 1.0596.It may have some relation however but not a simple one to the density of the solutions; sulphate of magnesia of which the solution is most dense being most slowly diffusive ;and salts of soda being slower its they are generally denser in solution than the corresponding salts of potash. Nor does it depend upon equal solubility for in none of the pairs is there any approach to equality in that respect PROFESSOR GRAHAM A comparison was now made of the diffusibility of several acids diffused from 4 per cent solutions from which it appeared that hydrochloric and nitric acids were sensibly equal and had ib diffusi-bility nearly double that of sulphuric acid. The diffusion of chloride of sodium being 13.32 grs.that of hydrochloric acid was 34.1 of nitric acid 33.5 of sulphuric acid 18*48,of oxalic acid 12.38,and of tartaric acid 99'9. Difusiors of arnmoniated salts of copper.-It was interesting to compare together such related salts as sulphate of copper the ammoniated sulphate of copper or soluble compound of sulphate of copper with 2 equivs. of ammonia and the sulphate of ammonia. It is well known that metallic oxides or subsalts of metallic oxides when dissolved in ammonia and the fixed alkalis are easily taken down by animal charcoal. This does not happen with the ordinary neutral salts of the same acids which are held in solution by a strong attraction. Supposing the existence of a scale of the solvent attraction of water the preponderance of the charcoal attraction will mark a term in that scale.And if the solvent force is nothing more than the diffusive tendency it will follow that salts which can be taken down by charcoal must be less diffusible than those which cannot Of sulphate of ammonia and of sulphate.of copper solutions were prepared consisting of 4anhydrous salt to 100 water the sulphate of ammonia being of course taken as NH,O.SO,. The solution of the copper-salt was divided into two portions one of which had caustic ammonia added to it in slight excess so as to produce the azure blue solution of ammonio-sulphate of copper. The solutions were diffused for eight days at a mean tempera-ture of 64*9 for the sulphates and nitrates and 67O.7 for the chlorides DIFFUSION OR SOLUTIONS 4 SALT TO 100 WATER.Density of solution Anhydrous salt Name of salt. at temperature of diffused in grains. experiment. Mean of 2 expts. Sulpbate of ammonia . . . . . 1.05235 12-05 Sulphate of copper . . . . . 1.0369 6.35 Animonio-sulyhate of copper . 1*0308 1-44 Nitrate of ammonia . . . 1.0136 15.80 1.0323 9-77 Nitrate of copper . . . . . 1*0228 1.56 Ammonio-nitrate of copper . . 1.0100 16.19 Chloride of ammonium . . . Chloride of copper . . . . . 1.0328 10-65 Ammonio-chloride of copper . 1*0209 4-24 It will be observed that the quantky of sulphate of copper diffused out in the experiments falls from 6.35 in the neutral salt to 1.44 grs. 265 ON TEE DIFFUSION OF LIQUIDS in the ammoniated salt; of nitrate of copper from 9.77 to 1.56,and of chloride of copper from 10.65 to 4-24 These numbers are to be taken only as approximations; they are sufficient however to prove a much reduced diffusibility in the ammoniated salts of copper.Di$usion of mixed salts.-When two salts can be mixed without combining it is to be expected that they will diffuse separately and independently of each other each salt following its special rate of diffusion. (1). Anhydrous sulphate of magnesia and sulphate of water (oil of vitriol) 1 part of each were dissolved together in 10 parts of water and the solution allowed to diffuse for four days at 61O.5. The water-jar was found to have acquired Sulphate of magnesia. . . 5.60 grs.Sulphate of water . 21-92 , 27.52 grs. (2). A solution was also diffused of 1part of anhydrous sulphate of soda and 1 part of chloride of sodium. in 10 parts of water for four days at 61O.5. The salt which diffused out in that time consisted of Sulphate of soda . . 9.48 grs. Chloride of sodium . . 17-80 , 27.28grs. The sulphate of soda in the last experiment had begun to crys-tallize in the solution-phial from a slight fall of temperature before the diffusion was interrupted it circumstance which may have con-tributed to increase the inequality of the proportions diffused of the mixed salts. (3). A solution of equal weights of anhydrous carbonate of soda and chloride of sodium namely of 4 parts of the one salt and 4 parts of the other to 100 water was diffused from three four-ounce phials of 1-25inch aperture at a mean temperature of 57O.9 and for seven days.The diffusion product amounted to 17*10 17.58,and 18-13grs. of mixed salt in the three experiments. The analysis of the last product of 18.13 grs. gave Carbonate of soda. . 5.68 31.33 Chloride of sodium . 1245 68.67 18.13 10000 The least soliible of the two salts appears in all cases to have its diffusibility lessened in the mixed state. The tendency to crystal-lization of the least soluble salt must evidently be increased by the admixture. Now it is this tendency or perhaps more generally the 266 PROFESSOR GRAHAM increased attraction of the particles of salt for each other when approximated by concentration which most resists the diffusion of a salt and appears to weaken the diffusive force in mixtures as it is also found to do so in a concentrated solution of a single salt.(5). The salt which diffused from a strong solution of sulphates of zinc and magnesia consisting of 1 part of each of these salts in the anhydrous state and 6 parts of water did not consist of the two salts in exactly equal proportions. The mixture of salts bffused for eight days as in the late experiments gave the following results Exp. 1. 11. 111. Sulphateof zinc . ..8*12 r.49 8.12 Sulphate of magnesia . 8.68 8.60 8.75 16.80 16.09 1687 There is therefore always a slight but decided preponderance of sulphate of magnesia the more soluble salt in the diffusion-product.It appeara from all these experiments that the inequality of diffusion which existed is not diminished but exaggerated in mixtures a curious circumstance which has also been observed of mixed gases. Separation of salts of dg'erent buses by di$usion.-It was now evident that inequality of diffusion supplies a method for the sepa- ration to a certain extent of some salts from each other analogous in principle to the separation of unequally volatile substances by the process of distillation. The potash-salts appearing to be always more diffusive than the corresponding soda-salts it follows that if a mixed solution of two such salts be placed in the solution phial the potash-salt should escape into the water atmosphere in largest proportion and the soda-salt be relatively concentrated in the phial.This anticipation was fully verified. (1). A solution was prepared of equal parts of the anhydrous carbonates of potash and soda in 5 times the weight of the mixture of water Diffused from a small thousand-grain phial of 1.1 inch aperture into 6 ounces of water for nineteen days at a temperature above SO0 it gave a liquid of density 1.0350 containing a con-siderable quantity of the salts in the proportion of .36.37 Carbonate of soda. Carbonate of potasb .r 100*00 A partial separation of the salts of sea-water was effected in a similar manner. (2). The sea-water (from Brighton) was of density 1*0265 One thousand grs of the liquid yielded 36.50 grs of dry salts of which ON THE DIFFUSION OF LIQUIDS.2.165 grs. were magnesia. The dry salts contain therefore 6.10per cent of that earth. Six thousand-grain phials of 1.1 inch aperture were properly filled with the sea-water and placed in six tumblers each of the last containing 6 ounces of water. Temperature about 50°. The diffu- sion was interrupted after eight days. The salt8 of the sea-water were now found to be divided as follows Diffused into the tumblers . 92.9 grs. or 36.57 Remaining in the phials . . 161.1 grs. or 63.43 -cI-.--r 254.0 10000 Rather more than one-third of the salts has therefore been trans-ferred from the solution-phials to the water-jars by diffusion. Of the diffused salts in the tumblers 46.5 grs.were found to contain 1.90 gr. magnesia or 409 per cent. Hence the follow-ing result Magnesia originally in salts of sea-water 6.01 per cent. Magnesia in salts diffused from sea-water . 4-09per cent. The magnesia also must in consequence be relatively concentrated in the liquid remaining behind in the phials. A probable explanation may be drawn from the last results of the remarkable discordance in the analysis of the waters of the Dead Sea made by different chemists of eminence. The relative proportion of the salts is referred to and not their absolute quantity the last necessarily varying with the state of dilution of the saline water when taken up. The lake in question falls in level 10 or 12 feet every year by evaporation. A sheet of fresh water of that depth is thrown over the lake in the wet season which water may be supposed to flow over a fluid nearly 1.2 in density without greatly disturbing it.The salts rise from below into the superior stratum of fresh water by the diffusive process which will bring up salts of the alkalis with more rapidity than salts of the earth and chlorides of either class more rapidly than sulphates. The composition of water near the surface must therefore vary greatly as this process is more or less advanced. Chemical analysis which gives with accuracy the proportions of acids and bases in a solution furnishes no means of deciding how these acids and bases are combined or what salts exist in solution. But it is possible that light may be thrown on the constitution of mixed salts at least when they are of unequal diffusibility by meam of a diffusion experiment.With reference to sea-water for instance it has been a question in what form the magnesia exists as chloride or as sulphate ; or how much exists in the one form and how much in the other. Knowing however the different rates of diffusibility of these two salts which is nearly chloride 3 and sulphate 2 and their rela- PROFESSOR GRAHAM tion to the diffusibility of chloride of sodium we should be able to judge from the proportion in which the magnesia travels in company with chloride of sodium whether it is travelling in the large pro- portion of chloride of magnesium in the small proportion of sulphate of magnesia or in the intermediate proportion of a certain mixture of chloride and sulphate of magnesia.But here we are met by a difficulty. Do the chloride of magnesium and sulphate of magnesia necessarily pre-exist in sea-water in the proportions in which they are found to diffuse? May not the more easy diffusion of chlorides determine their formation in the diffusive act just as evaporation determines the formation of a volatile salt -producing carbonate of ammonia for instance from hydrochlorate of ammonia with carbonate of lime in the same solution ? It was proved that liquid diffusion as well as gaseous evaporation can produce chemical decompositions. Decomposition of salts 6y d@usion.-From bisulphate of potash saturated at 68O and of density 1.280 there diffused out Sulphate of potash ;:::;} Bisulphate of potash.Sulphate of water Sulphate of water 12.77 44*61 It thus appears that the bisulphate of potash undergoes decompo- sition in diffusing and that the acid diffuses away to about double the extent in equivalents of the sulphate of potash. From a 4 per cent solution of alum at 64O,the diffision-product was found to be Alum . 5.33 71.26 Sulphate of potash 2.15 28.74 7-48 100-00 This otherwise stable double salt is broken up from the high diffusibility of the sulphate of potash compared with that of the sulphate of alumina; the separate diffusibilities of these two salts were observed to be nearly as 2 to 1. It was interesting to observe what really diffuses from the arnmo-niated sulphate of copper (CuO.SO,. 2NH,+HO) and to find if the low diffusibility of that salt is attended with decomposition. The diffusion of the ammoniated sulphate of copper was therefore repeated from a 4 per cent. solution in the six-ounce solution phial for eight days at 64O.2. In evaporating the water of the jar afterwards the ammoniated sulphate of copper present was necessarily decomposed by the escape of ammonia and a subsulphate of copper precipitated. The copper found however was estimated as neutral sulphate of ON THE DIFFUSION OF LIQUIDS. copper. The diffusion-product of two experiments may be represented as follows in grains 1. 11. Sulphate of copper Sulphate of ammonia . . . 0.81 5.46- 0.97 5-53- 6.27 6.50 The abundant formation and separation of sulphate of ammonia in these experiments prove that the ammoniated sulphate of copper is largely decomposed in diffusion.From the diffusion of the double crystallized sulphate of magnesia and potash compared with that of a mixture of its con- stituent salts it appeared that they were different and that double salts dissolve in water without decomposition although the single salts may meet in solution without combining. Hence in a mixture of salts we may have more than one state of equilibrium possible. And when a salt like alum happens to be dissolved in such a way as to decompose it the constituents are not necessarily reunited by subsequent mixing. Many practices in the chemical arts which seem empirical have their foundation probably in facts of this kind.Diflusion of one salt into the solution of another salt.-It was curious and peculiarly important in reference to the relation of liquid to gaseous diffusion to find whether one salt A would diffuse into water already charged with an cqual or greater quantity of another salt B as a gas a freely diffuses into the space already occupied by another gas b; the gas b in return diffusing at the same time into the space occupied by a. Or whether on the contrary the diffusion of the salt A is resisted by B. The latter result would indicate a neutralization of the water’s attraction for a second salt which would divide entirely the phenomena of liquid from those of gaseous diffusion. A solution of 4 parts of carbonate of soda to 100 water of density 1*0406was observed to diffuse with equal rapidity into a solution of 4 parts of chloride of sodium to 100 water having the density 1.0282 as into pure water.The same solution of carbonate of soda was diffused into a solution of sulphate of soda containing 4 per cent and of density 1.0352 with a small reduction in the quantity of carbonate of soda diffused amounting to one-eighth of the whole. The sulphate of soda there- fore exercised a positive interference in checking the diffusion of the carbonate to that extent. So small and disproportionate an effect however is scarcely sufficient to establish the existence of a mutual elasticity and resistance between these two salts. Still it might be said may not the diffusion of one salt be resisted by another salt which is strictly isomorphous with the first ? The PROFESSOR GRAHAM diffusion of a 4 per cent.solution of nitrate of potash however was found not to be sensibly reduced by the presence of 4 per cent of nitrate of ammonia in the water atmosphere. These experiments were made upon dilute solutions and it is not at all improbable that the result may be greatly modified in con- centrated solutions of the same salts or when the solutions approach to saturation. But there is reason to apprehend that the phenomena of liquid diffusion are exhibited in the simplest form by dilute solu- tions and that concentration of the dissolved salt like compression of a gas is often attended with a departure from the nornial character.On approaching the degree of pressure which occasions the lique- faction of a gas an attraction appears to be brought into play which impairs the elasticity of the gas; so on approaching the point of saturation of a salt an attraction of the salt-molecules for each other tending to produce crystallization comes into action which will interfere with and diminish that elasticity or dispersive tendency of the dissolved salt which occasions its diffusion. We are perhaps justified in extending the analogy a step further between the characters of a gas near its point of liquefaction and the conditions which may be assigned to solutions. The theoretical density of a liquefiable gas niay be completely disguised under great pressure.Thus under a reduction by pressure of 20 volumes into 1 while the elasticity of air is 19.72 atmospheres that of carbonic acid is only 16.70 atmospheres and the deviation from their normal densities is in the inverse proportion. Of salts in solution the densities may be affected by similar causes so that although different salts in solution really admit of certain normal relations in density these relations may be concealed and not directly observable The analogy of liquid diffusion to gaseous diffusion and vaporiza- tion is borne out in every character of the former which has been examined. Mixed salts appear to diffuse independently of each other like mixed gases and into a water-atmosphere already charged with another salt as into pure water.Salts also are unequally diffu- sible like the gases and separations both mechanical and chemical (decompositions) are produced by liquid as well as by gaseous diffusion. But it still remains to be found whether the diffusibilities of different salts are in any fixed proportion to each other as simple numerical relations are known to prevail in the diffusion-velocities of the gases from which their densities are deducible. It was desirable to make numerous simultaneous observations on the salts compared in order to secure uniformity of conditions particularly of temperature. The means of greatly multiplying the experiments were obtained by having the solution-phial cast in a mould so that any number could be procured of the same form ON THE DIFFUSION OF LIQUIDS.and dimensions. The phials were of the form represented (Fig. 2.) FIG. 2 holding about 4 ounces or more nearly 2080 grs. of water to the base of the neck and the mouths of all were ground down so as to give the phial a uniform height of 3% inches. The mouth or neck was also ground to fit a gauge-stopper of wood which was 0.5 inch deep and slightly conical being 1.24inch in diameter on the upper and 1.20 inch on the lower surface. These are therefore the dimen- sions of the diffusion aperture of the new solution cells. A little con-trivance to be used in filling the phials with the saline solution to a constant distance of half an inch from the surface of the lip proved useful. It was a narrow slip of brass plate having a descending pin of exactly half an inch in length fixed on one side of it.This being laid across the mouth of the phial with the pin downwards in the neck the solution was poured into the phial till it reached the point of the pin. The brass plate and pin being removed the neck was then filled up with distilled water with the aid of the little float as formerly. The water-jar in which the solution-phial stood was filled up with water also as formerly so as to cover the phial entirely to the depth of 1 inch. This water-atmosphere amounted to 8750 grs. or about 20 ounces A glass plate was placed upon the mouth of the water-jar itself to prevent evaporation. Sometimes 80 or 100diffusion cells were put in action at the same time.The period of diffusion chosen was now always exactly seven days unless otherwise men- tioned. DIFFUSION OF SALTS OF POTASH AND AMMONIA Solutions were prepared of the various salts in a pure state in certain fixed proportions namely 2 4 68 and 10 parts of salt to 100 parts of water by weight. The density of these solutions was observed by the weighing-bottle at 60°. The solutions were frequently diffused at two different temperatures j one the temperature of the atmosphere which was fortunately remarkably constant during most of the experiments to be recorded at present and the other a lower temperature obtained in a close box of large dimensions containing masses of ice. The results at the artificial temperature were obviously less accurate than those of the natural temperature but have still considerable value Three experiments were generally made upon the diffusion of each solution at the higher with two experiments at the lower temperature.The diffusion-products are expressed in grains. The meaa diffusion of the different solutions containing 2,4 6# and 10 parts of certain salts was as follows Diffusion at 64O.Z 2. 4. 63. 10. Carbonate of potash . 5.45 Sulphate of potash . . 5.52 Sulphate of ammonia . 5.58 10.25 10.57 10*51 16.67 17-17' 16.79 24.69 23.62 22.20 272 PROFESSOR GRAHAM Diffusion at 370.6 2. 4. 6%. Carbonate of potash . . 3.85 7-09 11.25 Sulphate of potash . . . 3.95 7-40 11-66 Sulphate of ammonia . 3.76 7.70 10.96 The proportions diffused are sensibly equal of the different salts at the higher temperature with the exception of the largest proportion of salt 10 per cent when a certain divergence occurs.This last fact is consistent with the expectation that the diffusion of salts would prove most highly normal in dilute solutions. Some of the irregularities at the lower temperature are evidently of an accidental kind. The neutral chromate and acetate of potash were diffused at a temperature ranging from 63O to 65O or at a mean temperature of 64O.1 which almost coincides with the higher temperature of the last experiments. Diffusion at 64O.1 ; Chromate of potash 5.77 Acetate of potash . . . 5-85 2. 11-19 10.70 4. 17.60 16.48 6g. 28-75 24-85 10. The 10 per cent solution of these two salts also agrees with the same solution of carbonate of potash which was 2469 grs.Nor do the lower proportions diverge greatly from the preceding group of salts. Another pair of salts were simultaneously diffused but with an accidental difference of O0-4of temperature Mean diffusion at 64O.1 and 64O-5 2. 4. Bicarbonate of potash . . 5-81 11-01 Bichromate of potash . . 5-65 11*49 It is singular to find that salts differing so much in constitution and atomic weight as the chromate and bichromate of potash may be confounded in diffusibility. The diffusion-products of these two salts are for the 2 per cent solutions 5.77 and 5.65 grs. and for the 4 per cent solution 11-19 and 11*49grs. The bicarbonate of potash also exhibits a considerable analogy to the carbonate but resembles still more closely the acetate.It is thus obvious that similarity or equality of diffusion is not confined to the isomorphous groups of salts. The nitrates of potash and ammonia have already appeared to be equidiffusive at two different temperatures. They were diffused again in the same proportions as the last salts at a temperature varying from 63O to 67'05. Diffusion at 65O.9 2. 4. 65 10. Nitrate of potash . . . 7.47 13.97 22.37 32-49 Nitrate of ammonia . 7.73 1448 22.74 34*22 ON THE DIFFUSION OF LIQUIDS. Although these salts correspond closely it is probable that neither the diffusion of these nor the diffusion of any others is absolutely identical. The nitrate of ammonia appears to possess a sli@t superiority in diffusion over the nitrate of potash which increases with the large proportions of salt in solution.They are both considerably more diffusible than the seven preceding salts. A second pair of isomorphous salts were compared the chlorides of potassium and ammonium. Diffusion at 66O.2 2. 4. 65 10. Chloride of potassiumChloride of ammonium 7.70 .7.81 15.29 14.60 2487 24-30 36.93 36.53 The quantities diffused of these two chlorides are more closely in proportion to the strength of the original solution than with any of the preceding salts of potash. Thus the quantities diffused from the 2 and 10 per cent solutions of chloride of potassium are 7.70 and 36.93 grs. which are as 2 to 9.6 or nearly as 2 to 10 Chlo-ride of sodium was observed before to be nearly uniform in this respect; but other salts appear to lose considerably in diffusibility with the higher proportions of salt.It is possibly a consequence of the crystallizing attraction to which reference was lately made coming into action in strong solutions and resisting diffusion. The salts of potash thus appeared to fall into two groupsJthe members of which have a nearly equal diffusibility at Ieast from weak solutions such as 1or 2 per cent Of what may be called the sulphate of potash class the diffusion from 1 per cent solutions was as follows Diffusion of 1per cent solutions at 58O.5 Carbonate of potash .. 2.63 grs. Sulphate of potash ... 2.69 JJ Acetate of potash ... * 2.68 YY Chromate Gf potash ..2.83 1J Bicarbonate of potash . .2.81 1, Bichromate of potash . ..2.88 1 Diffusion of salts of the uitre clam at 64O.5 1. 2. 4. Nitrate of potash. . 3.72 7-47 13.97 Nitrate of ammonia . 3.75 7.73 14.48 Chloride of potassium 3.88 7.70 15.01 Chloride of ammonium 3.89 7.81 1441 Chlorate of potash 3-66 7*22 13-31 -7 Mean * 3.78 7.58 14.23 What is the reIation betmcen these groups ? VOL. 111.-NO. xr. T PROFESSOR GRAHAM The diffusion of 4 per cent solutions of carbonate and nitrate of potash was repeated at a temperature rising gradually from 63"to 65' during the seven days of the experiment with a mean of 64O.1. The diffusion-products of the carbonate were 10.31 10.05 and 10.44grs. in three cells; mean 10.27 grs.Of the nitrate 13.98 13.86 and 13.60 grs. mean 13.81 grs There is thus a diffusion in equal times of Carbonate of potash . 1097 1 Nitrate of potash * . . 13.81 1.3447 But the numbers so obtained cannot be fairly compared owing to the diminishing progression in which the diffusion of a salt takes place. Thus when the diffusion of nitrate of potash was interrupted every two days as in a former experiment with chloride of sodium the progress of the diffusion for eight days was found to be as follows in a 4 per cent solution with a mean temperature of 66O. Nitrate of potash Diffused in first two days . . 454 grs. Diffused in second two days . 4.13 , Diffused in third two days . . . . 4.06 , Diffused in fourth two days . 3-18 ) 15.91 The absence of uniformity in this progression is no doubt chiefly due to the want of geometrical regularity in the form of the neck and shoulder of the solution-phial.A plain cylinder as the solution cell might give a more uniform progression but would increase greatly the difficulties of manipulation. The diffusion of carbonate of potash will no doubt follow a diminishing progression also; but there is this difference that the latter salt will not advance so far in its progression owing to its smaller diffusibility in the seven days of the experiment as the more diffusible nitrate does. The diffusion of the carbonate will thus be given in excess and as it is the smaller diffusion the difference of the diffusion of the two salts will not be fully brought out.The only way in which the comparison of the two salts can be made with perfect fairness is to allow the diffusion of the slower salt to proceed for a longer time till in fact the quantity diffused is tbe same for this as for the other salt and the same point in the pro-gression has therefore been attained in both; and to note required. The problem takes the form of determining the times of equal diffusion of the two salts. This procedure is the more necessary from the inapplicability of calculation to the diffusion progression. Further allowing the Times of Equal Diffusion to be found it is ON THE DIFFUSION OF LIQUIDS. not to be expected that they will present a simple numerical relation. Recurring to the analogy of gaseous diffusion the times in which equal volumes or equal weights of two gases diffuse are as the square roots of the densities of the gases.The times for instance in which equal quantities of oxygen and hydrogen escape out of a vessel into the air in similar circumstances are as 4 to 1 the densities of these two gases being as 16 to 1 Or the times of equd diffusion of oxygen and protocarburetted hydrogen are as 1.4142 to 1 that is as the square root of 2 to the square root of 1 the densities of these gases being 16 and 8 which are as 2 to 1. The densities are the squares of the equal-diffusion times. It is not therefore the times themselves of equal diffusion of two salts but the squares of those times which are likely to exhibit a simple numerical relation.While the 4 per cent solution of nitrate of potash was diffused as usual for seven days the corresponding solution of carbonate of potash was now allowed to diffuse for 9-90days; times which are as 1 to 1.4142. The results were as follows Wused of-Carbonate of potash at 64O.3in 9 9 days 13.92 , 100*8 The three experiments OR the nitrate of potash of which 13.81 grs. is the mean were 13-98,13.86 and 13.60 grs. as already detailed. The three experiments on the carbonate were 14*00 13.97 and 13.78 grs. The difference in the means of the two salts is only 0.11 gr. The explanation of such a relation suggested by gaseous diffusion is that the molecules of the two salts as they exist in solution have dserent densities that of nitrate of potash being I and that of car-bonate of potash 2.We are thus led to ascribe densities to the solution- molecules of the salts conceived on the analogy of vapour-densities. The two salts in question are related exactly like protocarburetted hydrogen gas of density 1,to oxygen gas of density 2. The parallel would be completed by supposing that the single volume of oxygen to be diffused was previously mixed with 100 volumes of air (or any other diluting gas) while the 2 volumes of protocarburetted hydrogen were also diluted with 100 volumes of air; the diluting air here representing the water in which the salts to be diffused are dissolved in the solution-phial. The time in which a certain quantity of proto-carburetted hydrogen would come out from a vessel containing I per cent of that gas being 1 (the square root of density l) the time in which an equal quantity of oxygen would diffuse out from a similar vessel containing 1 per cent also would be 1.4142 (the square root of density 2).The diffusion was repeated of 2 per cent solutions of the nitrate and carbonate of potash at a lower temperature by about 109 TZ 276 PROFESSOR GRAHAM The mean results were Nitrate of potash in seven days 12.22 grs in two cells 100 Carbonate of potash in 9*9days 12.40 ) , 101.47 Again at a still lower temperature the times being still as 1 to 1.4142. The results were 1 per cent solution of nitrate of potash in . 6-83 grs 100 nine days at 390.7 9 J9 1 , sulphate of potash in .. . 7.04 , . 103*07 12.728days at 390.7 . With 2 per cent solutions at the same temperature Nitrate of potash 6-83 grs. 100 99-85 Sulphateof potash 6.82 , The existence of the relation in question was also severely tested in another manner. Preserving the ratio in the times of dif-fusion for the two salts the actual times were varied in duration in three series of experiments as 1 2 and 3. The experiments were made in a vault with a uniformity of temperature favourable to accuracy of observation. Eight cells of the 1 per cent solution of each salt were always diffused at the same time Nitrate of potash at 47O.2,3.50grs. 100 3.5 and 49.5 days { Sulphate of potash at 47O*3,3*50grs 100 Nitrate of potash at 48O.6 6.04grs.100 7 and 9.9 days { Sulphate of potash at 49O*1,6*20 grs 102.65 Chromate of potash at 49O*1,6.29grs. 104.14 100 10%and 14.85 days { Nitrate of potash at 48*,8*74grs grs. 100.57 Sulphate of potash at 48O*6,8*79 The concurring evidence of these three series of experiments is strongly in favour of the assumed relation of 1 to 1*4142,between the times of equal diffusion for the nitrate and sulphate of potash, and consequently of the times for the two classes of potash-salts of which the salts named appear to be types. The same experiments are also valuable as proving the similarity of the progression of diffusion in two salts of unequal diffusibility Hydrate ofpotask-Of pure fused hydrate of potash a 1per cent solution was diffused from four cells for 495 days at a mean teni-perature of 530*7,against a I per cent solution of nitrate of potash in six cells for seven days at a mean temperature Oo-1 lower or of 53O.6.The hydrate of potash which diffused vas calculated from the chloride of potassium which it gave when neutralized by hydro-chloric acid. Hydrate of potash diffused in two cells 5.97 and 6.28 grs.; mean 6.12 grs. or 3.06grs for a single cell ON THE DIFFUSION OF LIQUIDS. 277 Nitrate of potash diffused in two cells 6922 654 and 5*93 grs:; mean 6.23 grs. or 3.11 grs. for a single cell The dif- fusion of riitrate of potash being 100 that of the hydrate of potash is 98.2 numbers which are sufficiently in accordance. But the times were as 1to 1.4142; and their squares as 1to 2.SO far then as one series of expcrirnents on hydrate of potash entitles US to conclude we appear to have for the salts of potash a close approximation to the following simple series of times of equal diffusion with the squares of these times Times. Squares of times. Hydrate of potash 1 1 Nitrate of potash . 1.4142 2 Sulphate of potash . 2 4 The diffusion of hydrate of potash at 390.7 with reference to COP responding solutions of nitrate of potash for the selected times was 8s follows 100 Nitrate of potash 1 and 2 per cent solutions . . Hydrate of potash 1per cent solution . . . . . 101.3 Hydrate of potash 2 per cent solution . . 99.4 These experiments at the low temperature concur therefore with those made at the higher temperature in proving that the times of equal diffusion of the two substaiices have been properly chosen.Dafasion of salts of soda.-The only salts of soda which have yet been diffused in a sufficient variety of circumstances are the car- bonate and sulphate. These salts appear to be equidiffusive but to diverge notwithstanding more widely in solutions of the higher pro-portions of salt than the corresponding potash-salts. It is a question whether this increased divergence is not due to the less solubility of the soda-salts and the nearer approach consequently to their points of saturation in the stronger solutions The mean results at 64O were as foliows 2. 4. 62. 10. Carbonate of soda . . . 414 7.78 12.22 16.88 Sulphate of soda .4.31 817 13.50 19-14 DIFFUSION OF 1 PER CENT SOLUTIONS AT 64O9 Carbonate of soda 2.32 grs. . . . . . 100 Sulphate of soda 2938 , . . . . . 102.58 The diffusion of the carbonate of soda was further compared with the nitrate of the same base to find whether their times of equal diffusion are related like those of the corresponding potash-salts. PROFESSOR GRAHAM 1 per cent solution of nitrate of soda in 7 days at 66O.9 in four cells 11.73 grs. 100 1 per cent solution of carbonate of soda in 9.9 days at 66O.9 11-62 grs. 99.06 2 per cent solution of nitrate of soda in 7 days at 54O.3 10.10 grs. + . 100 2 per cent solution of carbonate of soda in 9.9 days, 9.95 grs. . . . . . . .. 98.51. It appears probable therefore that the times of equal diffusion of the nitrate and carbonate of soda are related like those of the nitrate and carbonate of potash that is as 1 to 1.4142. In conclusion the results of most interest may be summed up, which this inquiry respecting liquid diffusion has hitherto furnished. 1. The method may be placed first of observing liquid diffusion. This method although simple appears to admit of sufficient exact- ness It enables us to make a new class of observations which can be expressed in numbers and of which a vast variety of substances may be the object; in fact everything soluble. DifFusion is also a property of a fundamental character upon which other properties depend like the volatility of substances; while the number of sub-stances which are soluble and therefore diffusible appears to be greater than the number of volatile bodies.2. The novel scale of solution-densities possessed by the mo-lecules of salts when liquid and in solution which are suggested by the different diffusibilities of salts and to which alone guided by the analogy of gaseous diffusion we can refer these diffusibilities. Liquid diffusion thus supplies the densities of a new kind of molecules but nothing more respecting them. The fact that the relations in diffusion of different substances refer to equal weights of those substances and not to their atomic weights or equivalents is one which reaches to the very basis of molecular chemistry. The relation most frequently possessed is that of equality the relation of all others most easily observed.In liquid d_lffusion we appear to deal no longer with chemical equivalents or the Daltonian atoms but with masses even more simply related to each other in weight. Founding still upon the chemical atoms we may suppose that they can group together in such numbers as to form new and larger molecules of equal weight for different sub- stances or if not of equal weight of weights which appear to have a simple relation to each other. It is this new class of molecules which appear to play a part in solubility rand liquid diffusion and not the atoms of chemical combination. 3. The formation of classes of equidi$usive substances. These classes are evidently often more comprehensive than the isomorphous groups.ON THE DIFFUSION OF LIQUIDS. 4. The Beparation of the whole salts (apparently} of potash and of soda into two divisions the sulphate and nitrate groups which must have B chemical significancy. The same division of the salts in question has been made by &I. Gerhardt on the grourid that the nitrate class is monobasic and the sulphate class bibaaic and is further supported by the state of condensation of the vapours of acids belonging to the different groups the equivalent of hydrochloric acid giving 4 and that of sulphate of water 2 volumes of vapour a relation quite analogous to that observed in the ‘I solution-densities.” 5. The application of liquid diffusion to the separation of mixed salts in natural and in artificial operations.6. The application of liquid diffusion to produce chemical decom- posit ions . 7. The assistance mdiich a knowledge of liquid diffusion will afford in the investigation of endosmose. When the diffusibility of the salts contained in a liquid is known the compound effect presented in an endosmotic experiment may be analysed and the true share of the membrane in the result be ascertained. Researches regarding the Molecular Constitution of the Volatile Organic Bases. By Dr. A. W. Mofmann F.C.S.* Among the various classes of organic substances there is perhaps none of which from an early period chemists have so constantly endeavoured to attain a general conception as the group of com-pounds which have received the name of organic bases all-and they are now very nurnerous-being capable of combining like the met& lie oxides with acids and being derived either from vital processes in animals OF plants or from a variety of artificial reactions con- ducted in the laboratory.The remarkable analogy between all these substances and ammo- nia which in its turn imitates as it were in its chemical deportment the mineral oxides naturally attracted the notice of chemists soon after Serturner’s discovery of the first of these alkaloids in the beginning of this century. Nor have they ever since been classified separately from ammonia ; philosophers have only differed as to the mode of their relation with the typical compound. Of the theories which have been enunciated respecting the consti- tution of the organic bases there are two of chief importance which may be designated as the arnmonia- and the amidogen-theory the former having been first proposed by Ber elius,? while the latter * Phil.Trans. 1850 I 93. .t. Trait6 de Chimie TI 2. 280 DR. HOFMANN we owe to Liebig.* Accordin5 to the former of the two chemists the ammonia would pre-exist in the organic bases; these bodies TI ould be conjugated compounds of ammonia with various adjuncts containing either carbon and hydrogen or these elements together with nitrogen oxygen and even sulphur compounds in which the original character of the ammonia has only been slightly modified by the accession of the adjunct. This view is chiefly supported by the mode and the proportions in which these alkaloids combine with acids and by the fact that various organic substances by directly uniting with ammonia give rise to the formation of basic compounds which are perfectly analogous to the alkaloids occurring in the eco- nomy of nature.According to Liebig’s opinion ammonia would no longer exist in the organic bases. At the time when Liebig$ wrote upon this subject the attention of chemists was much engaged with the study of the amides the prototype of which oxamide had then been discovered by Dumas. These substances all strictly neutral originate from ammonia by the loss of 1 equivalent of hydrogen which is abstracted by the oxygen or chlorine of certain electro-negative bodies (as in the formation of oxamide and benza-mide) a hypothetical substance amidogen H N remaining in combination with the oxide or chloride deprived of 1 equiv.of oxygen or chlorine. Liebig thought that the formation of the organic bases might take place in a similar manner namely by a reduction of ammonia to the state of amidogen by the action of electro-positivc organic oxides. Each of these theories being expressed in il simple formula the organic bases according to Berzelius would be represented by the terms H N 4-x while Lie big’ s view would characterize them as H N 4-y X denoting generally an organic compound containing carbon hydrogcn and possibly nitrogen oxygen and sulphur ; while Y ex-presses an organic oxide chloride &c. minus 1 equiv. of oxygen chlorine &c.Objections have been raised aFainst eitner theory and the opi- nions of cheniists have remained divided. Liebig has not returned any more to the subject but Berzelius took frequent occasion both in his “Annual Report,” and in the several editions of his (‘Trait6,” to defend his notion by the skilful interpretation of‘ every new fact which was elaborated by the progress of the science. The weight of * Handworterbueh der Chemie von L i e b i g W b h 1e r und P o g g e n d o r f f Bd. I 699. Artikel Organische Basen. .t. LOC,cit 235. ON THE VOLATILE ORGANIC BASES. 28 I his authority has n& been without influence for it cannot be denied that Berzelius's qiew has become more and more generally accepted especially since a series of comparative researches conducted of late upon the derivatives of the salts of ammonia and of organic bases appeared to give fresh support to this theory.These experiments pointed out that the elimination of hydrogen from organic bases and ammonia is by no means confined to 1 equivalent; oxalate of ammonia which by the loss of 2 equivs. of water is converted into oxamide when deprived of the whole of its hydrogen in the form of water becomes cyanogen (oxalonitrile) ; an analogous change occurs with the acid salts of ammonia resulting in the formation of two classes of compounds differing the one by 2 the other by 4 equivalents of water from the original salt. The representation of several of these groups in analogous deriva- tives from the salts of organic bases especially from the salts of aniline could not but strengthen the belief that ammonia actually pre-exists in the organic alkaloids.Incidentally to some researches communicated to the Chemical Society of London,* I gave a synop-sis of all the facts supporting the view of Berzelius. The prosecution however of this inquiry has elicited many points which are scarcely reconcilable with this theory. In another paper? I endeavoured to show that the force of the argument in favour of this view derived from the considerations just stated is greatly neu- tralized on the completion of the comparison between the two series by the failure of the analogy just at the point where its occurrence would have been most decisive. Now this very failure is not only in perfect harmony with but would be required by the theory of amidog en -b a ses .Yet stronger grounds for the acceptation of the latter view have been afforded by a splendid investigation of M. Wurtzt on the compounds of ethers with cyanic acid which have actually realized a series of substances anticipated in a most remarkable manner by Liebig on the theoretical ground of his conception of the nature of these compounds. Instances of such anticipation of discovery are so rare that I may be allowed to quote the words in which Liebig predicted nearly ten years ago the discovery of M Wurtz :-" If," said Liebig,$ in continuing the development of his ideas respecting the constitution of the organic bases '(we were enabled to replace by amidogen the oxygen in the oxides of methyl and ethyl in the oxides of two basic radicals we should without the slightest doubt * Researches on the Volatile Organic Bases 111.Action of Chloride Bromide and Iodide of Cyanogen upon Aniline; Chem. SOC.Qu J. I 285. ./-Chem. Soc. Qu. J. 11 331. 1 Compt. Rend. XXVIII 223 LOC.cit. 235. DR. HOFMANN obtain a series of compounds exhibiting a deportment similar in every respect to that of ammonia. Expressed in symbols a compound of the formula C H,. H N = E. Ad would be endowed with basic properties.’’ Now these compounds imagined in 1840 by Liebig in illustra- tion of his views have sprung into existence in 1849 with all the properties assigned to them by that chemist.At the beginning of the present year M. Wurtz in investigating the cyanates of ethyl methyl and amyl arrived at the unexpected result that these com- pounds when decomposed by potassa undergo a change analogous to that of cyanic acid. This acid when treated with potassa yield- ing carbonic acid and ammonia the corresponding ethers were split into carbonic acid and compound amnionias of the exact formula indicated in Liebig’s suggestion. It would be difficult to imagine a more brilliant triumph for any theoretical speculation ;I have however no doubt that even the illus- trious propounder of this view is at present far from believing that all the organic bases are amidogen-compounds. The progress of our knowledge has changed the form of this view without shaking its foundation.A good theory is more than a temporary expression of the state of science collecting under a general view the facts acquired up to the moment of its birth. It will not like ephemeral hypo- thesis vanish before the light of succeeding discoveries but expand- ing with the growth of science it will still correctly represent the known facts though of necessity modified into a more general expression. Such a theory then was that of Liebig. Resting as it did upon the facts observed in the formation of the neutral amides it was as originally framed an expression of the knowledge we then possessed. Subsequent researches showed that it was not only the 1 equivalent of hydrogen (the abstraction and replacement of which had led us to amidogen and the amides) that could be removed from the ammonia but that similarly 2 equivalents and even the whole of the hydrogen could be withdrawn from their position in this base and substituted by other atoms as in the imides and nitriles.If then we give to Liebig’s view the extension of which it natu-rally admits and which is demanded by the onward steps of science we arrive at a more general conception of the nature of the organic bases; amidogen and the amides now presenting themselves to us only as particular instances of the permutations possible among the elements of the primary type ammonia. It seemed but logical to look among the bases for analogues too of the imidogen-compounds and the nitriles. In other words it appeared desirable to inquire ON THE VOLATILE ORGANIC BASES.283 whether the several equivalents of hydrogen in ammonia could not be replaced not only by atoms neutralizing the basic properties of the original system but also by elements or groups of elements not affecting or but slightly modifying the alkaline character of the primary compound. Were this possible we should arrive at the formation of three classes of organic bases derived from ammonia by the replacement respectively of 1 2 or 3 equivalents of hy-drogen. Expressed in formdze these compounds would be first class provisionally called amidogen-bases. X second class provisionally called imidogen-bases. Y XI N =Bases of the third class provisionally called nitrile-bases. The bases belonging to the first class are pretty numerously repre- sented.Aniline methylamine ethylamine amylamine when con-sidered as amidogen-compounds belong to this group. } N = Methylamine N = Aniline ::> c, H c H3 H" } N = Ethylamine N = Amylamine H c,,H 1 c49 Bases of the second and third of the above classes had not been hitherto obtained although it is not improbable that many of the alkaloids whose constitution is at present perfectly unknown may be found on a closer investigation to be members of these latter groups. ACTION OF PHENYL-ALCOHOL ON ANILINE My endeavours to introduce into aniline a second equivalent of phenyl in order to convert Hl H1 DR. HOFMANN have been unsuccessful up to the present moment.I had hoped that this conversion might be effected by the action of phenyl-alcohol on aniline according to the followiiig equation H Phenyl-alcohol however has neither at the common nor at a high temperature-the mixture was exposed for several days in a sealed tube to 250° in an oil-bath-any action upon aniline. This experiment when repeated for a longer period might possi- bly give a more satisfactory result. It is known that ammonia by a similar treatment with phenyl-alcohol is likewise only very slowly converted into aniline. The action of chloride and bromide of phenyl C, H C1 and C, H Br upon aniline promised a better result; but the difficulties which I encountered in preparing these compounds which are as yet but very imperfectly investigated deterred me from further pursuing this direction of the inquiry.Much more successful were my endeavours to substitute methyl ethyl and amyl for the remainder of the basic hydrogen in aniline ACTION OF BROMIDE OF ETHYL UPON ANILINE. On adding dry bromide of ethyl to aniline no change takes place in the cold but on gently heatin8 the mixture in an apparatus which will allow the volatilized bromide to return to the aniline a lively reaction ensues. The liquid remains for some time in a state of ebullition and solidifies on cooling into a mass of crystals. If a cold mixture of the two bodies be left for a few hours it deposits crystals which are much more definite than those obtained on the cooling of the hot solution. In either case the fluid assumes a deep amber colour which approaches brown and the crystals are usually slightly yellow.These crystals vary in composition according to the proportions in which the two bodies have becn mixed. If a very large excess of aniline has been used they are of a prismatic cha-racter and consist of pure hydrobromate of aniline. On the other hand if the bromide of ethyl predominates to a con- siderable extent the crystals are flat four-sided tables sometimes of considerable size. Several analyses the details of which will be found below showed that they were the hyclrobroniate of a new base,* represented by the formula * Frequently as may be imagined mixtures of the two hydrobromates are deposited according to the proportion in which the constituents are mixed.ON THE VOLATILE ORGANIC BASES. i. e. of aniline in which 1 equiv. of hydrogen is replaced by 1equiv. of ethyl or ammonia in which 2 equivs. of hydrogen are replaced, the one by phenyl the other by ethyl The same base is contained in the free state either alone or mixed with aniline in the mother- liquor of the crystals of hydrobromate of aniline ; while the mother- liquor of the hydrobromate of the new base especially if a large excess of the bromide has been employed and after some days’ standing consists of nearly perfectly pure bromide of ethyl only a small quantity of the hydrobromate in question being kept in solu-tion. The formation of the new basic compound for which I propose the name Ethylaniline or Ethylophenylamine takes place by the removal from aniline of 1 equiv.of hydrogen in the form of hydrobromic acid for which an equivalent of ethyl is substituted the compound thus produced uniting with the hydrobromic acid. Hence the action of bromide of ethyl upon aniline may be repre- sented by the following two simple equations 2C, H N + C H Br = C,,H7 N. H Br + C, H, N +u-u Aniline. Bromide of Hydrobromate of E thylaniline ethyl. aniline. Anhe. Bromide of Hj-drobrbmate of ethyl. ethylaniline. Ethylaniline(~~~~Zo~~en~Za~ine) .-This base may be readily ob-tained in a state of purity by decomposing the solution of the hydro- bromate with a concentrated solution of potassa. A brown basic oil yises at once to the top of the liquid; it is separated by means of a pipette or a tap-funnel and subjected to rectification after having been freed from water by standing over solid potassa.Thus a colourless transparent oil is obtained which rapidly turns brown on cxposure to air and light and has a very high refractive power. It has all the properties of the oily bases in general. From anilinc it is distinguished by a slight difference in the odour perhaps imper- ceptible to an inexperienced nose by a higher boiling-point and a lower specific gravity. Ethylaniline boils (from platinum) constantly at 204*,the boiling-point of aniline being 182O; the specific gravity of this base is 0954 at ISo that of aniline being 1.020 at 16O. Ethylaniline does not exhibit the violet coloration with chloride of lime which characterizes aniline.Its acid solutions impart a yellow colour to fir-wood and the pith of elder-tree although less intensely than those of aniline. By dry chromic acid the base is inflamed like aniline. Analysis led to the formula DR HOFMANN The aalts of ethylaniline are remarkable for their solubility espe- cially in water. They are not easily obtained in well-defined crys- tals from an aqueous solution. From alcohol in which they are somewhat less soluble than in water several salts may be readily crystallized. Both the hydrochlorate and oxalate are obtained only on evaporating their solutions nearly to dryness when the salts separate in the form of radiated masses; the sulphate and nitrate have not as yet been obtained in the solid form.Hydrobromute of Ethyluniline.-The hydrobromate is extremely soluble in water but crystallizes on spontaneous evaporation of its alcoholic solution in splendid regularly formed tables of consider-able size and perfect beauty. I intend to give the measurement of these crystals in a future communication. The composition of this salt dried at looo is represented by the formula CI6 H, N H Br. The hydrobromate of ethylaniline when gently heated sublimes like the corresponding aniline-salt in splendid needles but when subjected to the action of a rapidly increasing heat it undergoes a very remarkable decomposition being redecomposed into aniline and bromide of ethyl. On addition of hydrochloric acid to the distillate the aniline dissolves while the bromide of ethyl collects as a heavy oil at the bottom of the vessel.C16HI N. H Br = C, H7 N + C H Br -uu Hydrobromate of Aniline. Bromide of ethylaniline. ethyl. I have in vain tried to split hydrobromate of aniline according to the equation C, H N. H Br = H N + C, H Br -+ Hydrobromate of Bromide of aniline. phenyl. This salt sublimes even when suddenly heated without any decomposition. Platinum-salt of -Ethylanilk-I have controlled the formula of ethylaniline moreover by the analysis of the platinum double salt of this substance. This salt is likewise very soluble and may by this property be distinguished from the corresponding aniline-salt ; on addition of a concentrated solution of bichloride of platinum to a concentrated solution of this hydrochlorate a deep orange-red oil is deposited which solidifies sometimes only after half a day with crystalline texture.If a moderately concentrated solution be em-ployed the salt crystallizes in the course of a few hours in magni- ficent yellow needles often an inch in length. On account of its great solubility in water and alcohol it has to be washed with a 287 ON THE VOLATILE ORGANZC BASES. mixture of alcohol and ether in which the latter predominates. It may be dried at looowithout decomposition. Formula C, H, N. H Cl Pt CI,. Terchloride of gold and protochloride of mercury yield with solu- tions of ethylaniline yellow oily precipitates which are very readily decomposed. Of the products of decomposition of ethylaniline I know as yet almost nothing although they will not be deficient in interest in a theoretical point of view.The action of bromine gives rise to the formation of two corn- pounds both crystalline one basic the other indifferent and cor-responding probably to tribromaniline. Neither of these substances has yet been analysed. On passing cyanogen into an alcoholic solution of ethylaniline short yellow prisms are deposited after some time which are evi-dently cyanethylaniline Cy C, HI N corresponding to cyaniline and cyanocumidine.* This new cyanogen-base dissolves in dilute sulphuric acid and is thrown down from this solution by ammonia in form of a floury precipitate. The hydrochlorate like the corre-sponding ycaniline-salt is very insoluble in hydrochloric acid.It may be obtained in fine crystals on addition of hydrochloric acid to a solution of the base in dilute sulphuric acid. Cyanethylaniline, like cyaniline forms a very soluble platinum-salt. I have made also some qualitative experiments respecting the deportment of ethylaniline with chloride of cyanogen. This gas is rapidly absorbed much heat being evolved. On cooling the mass solidifies into a resinous mixture of a hydrochlorate and a neutral oil which separates on addition of water. The base separated from the hydrochlorate is an oil and volatile ;while melaniline produced in the corresponding reaction of chloride of cyanogen with aniline is solid and non-volatile. Bisulphide of carbon gives rise to a gradual evolution of hydro-sulphuric acid no crystals being deposited from the uiixture.Phosgene gas acts powerfully on ethylaniline a liquid compound being formed together with hydrochlorate of ethylaniline. No analysis having as yet been performed of these compounds I refrain from entering into any further details. ACTION OF BROMIDE OF ETHYL UPON ETHYLANILINE. The phenomena attending the action of bromide of ethyl upon ethylaniline resemble those which are observed in the corresponding treatment of aniline. The reaction however is less powerful another * Chem. SOC. Qu. J 1 159. DR HOFMANN equivalent of hydrogen in aniline being less easily eliminated or replaced. Four or five days elapse before the separation of crystals commences at common temperatures.The formation however is considerably accelerated on application of heat. The experience obtained in the preparation of ethylaniline sug-gested at once the use of a very large excess of bromide of ethyl by which the formation of one compound only was secured. The mixture assumed a light-yellow colour turned gradually brown and deposited after five days four-sided tables of considerable size and remarkable beauty. The mother-liquor was coloured bromide of ethyl leaving when distilled off a small quantity of the same crys- talline compound. The substance in question was the pure hydrobroniate of a new base which is represented by the formula i. e. of ethylaniline in which 1 equiv. of hydrogen is replaced by ethyl or aniline in which 2 equivs.of the same radical are substi- tuted for a corresponding number of hydrogen-equivalents or lastly ammonia in which the 3 equivalents of hydrogen are replaced the one by phenyl the two others each by ethyl. The formation of this new substance €or which I propose the name diethylaniline or diethylophenylamine requires no further illus- tration it is absolutely analogous to the production of ethyl-aniline Diethy luniline (Diethyl0;vhenylamine).-The preparation of this compound in a state of purity resembles that of the preceding base whose physical properties have been only slightly modified by the introduction of the second equivalent of ethyl. The specific gravity wasfound to be 0.939 at 18* showing a slight decrease when com- pared with that of ethylaniline (0.954).The boiling-point however was raised nearly 10 degrees ;diethylaniline boils quite constantly at 213O.5. Diethylaniline is moreover distinguished from ethylani- line by remaining perfectly bright and colourless when exposed to the air. Like ethylaniline it still imparts a yellow colour to fir-wood; but like the former fails to affect a solution of hypochlorite of lime Composition C," I& N. Hydrohornate of DiekhyluniZine.-I have mentioned this salt when speaking of the formation of the second base. It is extremely solu-ble and resembles in every respect the corresponding ethylaniline- compound. Composition C, H, N N Br ON THE VOLATfLE ORGANIC BASES. The hydrobromate of diethylaniline when gently heated fuses and sublimes like the corresponding aniline- and ethylaniline-salts.When rapidly heated it is entirely converted into a colourless oil which distils over. This oil contains equal equivalents of bromide of ethyl and ethylaniline. By this distillation we obtain indeed the very constituents from which the hydrobroniate was originally pre- pared and which would of course reconvert themselves into hydro- bromate of diethylaniline. Only a trifling amount of undecomposed liydrobromate covers after the distillation is finished the sides of the retort in the form of a radiated coating. The peculiar deportment then of the hydrobromates of the ethyl- bases and probably of all their salts allows us to remove the several equivalents of ethyl one after the other from our fabric in the same manner as we had inserted them.When first I became acquainted with diethylated aniline having then already observed the deportment of the salts of ethylaniline which under the influence of heat are reconverted into aniline I indulged for a moment in the pardonable illusion that the salt of diethylaniline would exhibit the meta-morphosis C, H, N. H Br = C, H N + C H Br L7F-L v u Hydrobrbmate of Aniiine. Bromide of diethylaniline. butyl. a mode of reaction which would have afforded a passage from the ethyl- into the butyl-series. This step however is reserved for a more fortunate experimenter. Piatinurn-salt of Diethylaniline.-This salt resembles the corre-sponding compound of ethylaniline.On addition of a concentrated solution of bichloride of platinum to the hydrochlorate it is precipi-tated in the form of a deep orange-coloured oil which rapidly solidifies into a hard crystalline mass. If the solutions are mixed in a dilute state the salt is separated after some time in cross-like yellow crystals. It is not nearly so soluble in water and alcohol as the eth ylaniline-salt . Formula C, H, N .H C1. Pt C1,. I have not examined any other of the salts of diethylaniline :their deportment resembles in every respect that of the ethylaniline-salts. ACTION OF BROMIDE OF ETHYL ON DIETEYLANILINE. If we assume that the series of bases aniline ethylaniline and diethylaniline arise from the gradual elimination of the 3 equi-valents of hydrogen in ammonia and their substitution by 1equiva-lent of phenpl and 2 equivalents of ethyl it is difficult to imagine that bromide of ethyl should have any further action on cliethylani-VOL IIT.-NO.XI. u 290 DR. HOFMANN line this compound ammonia containing according to this view no longer any replaceable hydrogen. This conclusion appears to be supported by a series of experiments performed for this purpose; still the results obtained have elicited some points which require further elucidation. In aniline ethylaniline and diethylaniline then we have three bases which may be considered as derived from ammonia by the elimination and replacement of its three hydrogen-equivalents. The successive formations of ethylaniline and diethylaniline from aniline have been detailed in the preceding paragraphs; the passage of ammonia into aniline when exposed to the action of a phenyl-compound has been proved at an earlier period by some experiments made jointly by M.Laurent and myself upon the action at a high temperature of hydrated oxide of phenyl on ammonia. In this reaction a small but unequivocal quantity of aniline is formed. The formation of aniline ethylaniline and diethylaniline appeared to have established in a sufficiently satisfactory manner the point of theory which is here in question; still I thought desirable the acqui- sition of additional facts in support of the position to which this inquiry has conducted me. Thus I have been led to study the action of bromide of ethyl upon several of the derivatives of aniline and to try whether other alcohol-radicals such as methyl and amyl woulcl have a similar action; lastly in order to complete the investigation I was obliged to leave the amidogen-bases altogether in order to submit the typical ammonia itself to examination.Among the bases derived from aniline there is a class whose deportment with bromide of ethyl appeared to be more particularly worthy of a careful investigation. This is the group of compounds produced from aniline by substitution and embracing chloraniline dichloraniline and trichloraniline the corresponding bromanilines iodaniline and nitraniline. The question arose in what manner will these substances in which the original aniline has lost already a certain quantity of its hydrogen comport themselves under the influence of bromide of ethyl? The answer afforded by experiment was unequivocal and in perfect accordance with the result antici- pated bytheory although it may here at once be stated that the difficulty of obtaining the compounds in question in suflicient quan- tity has prevented me from pursuing this part of the investigation as far as I could have wished.ACTION OF BROMIDE OF ETHYL UPON CHLORANILINE. A solution of chloraniline in dry bromide of ethyl exhibits no apparent change even after several days’ exposure to the temperature of boiling water. On adding however water and distilling off the excess of bromide of ethyl it was found that the chloraniline had been converted into a hydrobromate which was held in solution ON THE VOLATILE ORGANIC BASES.291 scarcely a trace of uncombined base being left. Addition of potassa to the solution of the hydrobromate separated at once a yellow oily base of a very characteristic aniseed-odour differing from chlorani- ine in many respects. It remained liquid even at the temperature of a cold winter day while chloraniline is distinguished by the facility with which it crystallizes. Its salts are much more solublc than the corresponding chloraniline-salts I have only seen the sul- @ate and oxalate in a crystallized state. This liquid base is evidently ethylochloraniline I am sorry that I have not been able to verify this formula by direct analysis. The amount of substance at my disposal precluded the idea of submitting it to the processes of purification necessary before combustion.1 had hoped to fix its composition by the determina- tion of the platinum in the platinum-salt. Unfortunately this salt separated in the form of a yellow oil which could not by any means be made to crystallize. Obliged to desist from direct analysis 1 endeavoured to gairi the requisite data by another mode of pro-ceeding. ACTION OF BROMIDE OF ETHYL UPON ETHYLOCHLORANILINE. Recollecting that in almost all the instances which I have ex- amined the tendency exhibited by the various bases of producing readily crystallizable platinum-salts increased with the degrce of their ethylation I subjected the whole aniount of the still hypothe- tical ethylochloraniline after having dried it by a current of hot air to the action of a considerable excess of bromide of ethyl.After two days’ exposure to 1000 the mixture was found to contain a hydro-bromate in solution not a trace of free base being left. There was no doubt that a second equivalent of ethyl had been assimilated. On decomposing the hydrobrom ate with potassa an oil separated resembling in its appearance and also in its odour the preceding compound. An attempt to purify the ethylochloraniline from the yotassa by distillation with water having failed on account of the high boiling-point of this substance the purification of the diethylo- chloraniline for as such the new compound was to be considercd was at once effected with ether. The ethereal solution of the oil was carefully washed with water to remove adhering potassa and eva-porated the yellow oil rcmaining after this treatment was dissolved in hydrochloric acid and the solution mixed with biehloriile of platinum.Immediately a splendid orange-yellow crystalline precipi- tate was separated which after washing with water was fit fbr analysis. This salt fused at looo. Formula C, H, C1 N. H C1. Pt Cl,. u2 DR HOFMANN This result shows that chloraniline when subjected to the action of bromide of ethyl exhibits absolutely the same deportment as aniline itself two equivalents of ethyl being consecutively intro- duced which give rise to the formation of two new terms which demand the names ethylochloraniline (ethylochlorophenylamine) and diethy lochloraniline (diethylochlorophen ylamine) .ACTION OF BROMIDE OF ETHYL UPON BROMANILINE. The absolute analogy existing between chloraniline and bromani- line to which I have alluded in a former paper,* is maintained also in the deportment of these two substances towards bromide of ethyl. Bromaniline is rapidly converted into hydrobromate of ethylobro- maniline which could not except by analysis be distinguished from the corresponding chlorine-base. The platinum-salt being likewise a viscid oil I have omitted to analyse it. There is however no doubt about the existence of an ethylobronianiline C, H, Br N. I have not attempted to ethylate this compound any further. ACTION OF BROMIDE OF ETHYL UPON NITRANILINE. Ethylonitraniline (Ethyloiiitrophenylamine).-Nit raniline readily dissolves in bromide of ethyl.The solution soon deposits even at the common temperature pale- yellow crystals of considerable size. At the boiling temperature of water the conversion is rapidly accom- plished. On addition of an alkali to the hydrobromate the ethylo- nitraniline separates as a brown oily mass which solidifies after some time with crystalline structure. In this substance as well as in the other ethylated bases the properties of the mother-compound are only slightly modified. Thus we find in the base ethylonitraniline still the yellow colour of nitraniline which it readily imparts to the skin but which it loses altogether in its salts. These salts are as easily soluble in water as the corresponding nitraniline-compounds if not even more so and possess the same peculiar sweetish taste; they all crystallize however on evaporating their solutions nearly to dryness.Ethylonitraniline dissolves readily in ether and alcohol less so in boiling water; from a solution in the latter the base is deposited in stellated groups of yellow crystals which are readily distinguished from the felted mass of long needles separated on cooling from an aqueous solution of nitraniline. I have fixed the composition of ethylonitraniline by a singIe number namely by the determination of the metal in the platinum double salt. This compound is prepared by adding bichloride of platinum to a very concentrated solution of the hydrochlorate; this * Chem.SOC. Mem. 11 291. ON THE VOLATILE ORGANIC BASES. must not contain much free acid in which the salt would redissolve. After a short time pale-yellow scales are separated which have to be washed with cold water. Composition C16 HI N 0,. H c1. Pt Cl,. The nitraniline-salt contains 28.66 per cent of platinum. I have not prepared a diethylonitraniline. The deportment of chloraniline bromaniline and nitraniline with bromide of ethyl appears to throw much light upon the con-stitution of these substitution-bases. The possibility of introducing into these substances 2 equivalents of ethyl shows that they must contain the same amount of basic hydrogen (an expression by which I may be allowed to represent briefly the hydrogen of the ammonia-skeleton) as aniline itself and hence it is evident that it was the hydrogen of the phenyl which was replaced by chlorine bromine and hyponitric acid in the transformation of aniline into its chlorinated bromiuated &c.relatives. This transformation is due to a secondary substitution affecting the hydrogen in the radical which replaced the original ammonia- hydrogen; and the constitution of the substances in question may hence be graphically represented by the following formu12 H Chloraniline . . . *{ c,t H Ethylochloraniline . + . Diethylochloraniline . .{:;2 (!i)}N* H Bromaniline . . . Ethylobromaniline . . . Nitraniline . . . . . DR. HOFMANN This mode of viewing their constitution is in perfect harmony with the facts at present in our possession both as regards the deport- ment of the substitution-anilines and the substances similarly derived from hydrated oxide of phenyl.Experiment has shown that in aniline 1 2 or 3 equivalents of hydrogen may be replaced by chlorine bromine and probably also by the elements of hyponitric acid.* In these substances their basic properties gradually diminish with the successive insertions of chlorine or bromine into the compound Bromaniline still retains a strongly alkaloidal character which in dibromanilinc is so far impaired that by simple ebullition it is separated from its aqueous saline solutions ; tribromaniline lastly is a perfectly indifferent compound. Now if we recollect that in monobroniinatecl and dibrominated phenole (obtained by ill.c1ahours by distilling respectively bromosalicylic and dibro-uiosalicylic acid) the original character of hydrated oxide of phenyl is gradually altered and becomes in tribromopbenole (bromo-phenisic acid of ill Laurent) powerfully acid we cannot be sur-prised to find that the gradual development of electronegative properties in the radical should affect the nature of a basic system in which it replaces hydrogen. We have two parallel groups of bodies the chemical character of which is differently affected by the modi- fication induced in the radical existing in both by the assimilation of bromine. Hydrated protoxide of phenyl HO. C, H 0 slightly acid. Bromophenole . . . . . HO C, { z }O,more so Dibromophenole.. . . €30.C, { 2 }O more so. i:3} Tribromophenole } * Bromophenisic acid { '153 o,Po~erfullYacid* * At the present moment we have only nitraniline but it is scarcely to be doubted that we shall soon become acquainted with the nitro-terms corresponding to dichlo- raniline and trichloraniline. Recent researches of M. Cahows (Ann. Ch. Phys. [3] XXXVII 439) on the derivatives of anisole have pointed out the first alkaloid contain- ing 2 equivs. of hyponitric acid. Anisidine . . . C, II N 0,. Nitranisidine . . C14{ }N 0,. Dinitranisidine . C14{ H7 PO,) }N 0,. In this series oaly trinitranisidine C 1N 0,is wanting. {(a4l3 ON THE VOLATILE ORGANIC BASES. . . . . . {c12EH5} Phenylamine N powerfully basic.Tribromophenylarnine (tribromaniline) is a compound differing in its nature in no way from oxamide. Both these substances are ammonia whose basic character has been counterbalanced by the insertion of a powerfully electronegative radical in the place of' one of the hydrogen-equivalents. These two substances when subjected to the influence of strong acids comport themselves in exactly the same manner; they both reproduce ammonia the one with formation of tribromophenisic the other of oxalic acid. The paragraphs now following are devoted to a brief account of the bases derived from aniline by the insertion of methyl and amyl. I have not however followed out the examination of these sub-stances to the same extent the principle having been in fact sufficiently established by the formation of the ethyl-bodies.ACTION OF BROMIDE AND IODIDE OF METHYL UPON ANILINE. MethyZaniZine (Methylophenylarnine).-The deportment of aniline with bromide of methyl resembles its behaviour with the ethyl-compound. The mixture rapidly solidifies into a crystalline mass of hydrobromate of methylaniline. Bromide of methyl being extremely volatile I have used also the iodide which boils at a more con-venient temperature. The action of the latter compound upon aniline is very remarkable the evolution of heat on mixing the two substances being so great that the liquid enters into violent ebul- lition so that unless the substances be mixed gradually the erystal- line hydriodate which is formed immediately is actually thrown out of the vessel.Rilethylaniline when separated from the hydrobromate or hy-driodate appears as a transparent oil of a peculiar odour somewhat DR. HOFMANN different from that of aniline and boiling at 192O; it has retained the properties of aniline in a higher degree than the ethy'fated corn- pound. This substance yields still the blue coloration with hypochlorite of lime although in a less degree than aniline. Its salts are less soluble than those of ethylaniline; they are at once formed in the crystalline state on addition of the respective acids ; the oxalate crystallizes very easily but is rapidly decomposed with reproduction of aniline and probably with formation of oxalate of methyl. The composition of methylaniline is represented by the ex-pression I have established this formula by the analysis of the platinum- salt.This is precipitated as a transparent oil which rapidly changes into pale-yellow crystalline tufts resembling the corresponding aniline-salt but liable to rapid decomposition. The washing must be quickly done for the salt is extremely soluble in water and must be immediately followed by desiccation. Even when very carefully prepared it has become dark by the time it is ready for combustion. It turns instantaneously black if an alcoholic solution of the hydro- chlorate be employed for its preparation. Formula C, H N. H C1 Pt Cl,. I have not attempted to form a dimethylaniline. ACTION OF IODIDE OF METHYL UPON ETI-IYLANILINE. ~et~~y~et~~za~~~~ne .-I have established (Metl72yZet~yZophenylamine) the existence of this compound merely by qixalitative experiments.The mixture of ethylaniline and iodide of methyl begins to crystallize after two days' exposure to the temperature of boiling water. Me-thylethylaniline resembles the preceding base in its odour but has no longer any action upon hypochlorite of lime. I had not prepared a sufficient quantity of the compound for a determination of the boiling-point. The salts of this base are extremely soluble. With the exception of the hgdrobromate I have not been able to obtain a single one in crystals. Even the platinum-salt is not to be obtained in the crystalline form; it is extremely soluble aid separates if very concentrated solutions be eniployed as a yellow oil which does not solidify even after lengthened exposure to the air.This circumstance has prevented me from fixing the composition of methylethylaniline by a number. ON THE VOLATILE ORGANIC BASES. 29? It cannot however be doubted that it is represented by the formula "his compound presents a certain degree of interest inasmuch as the 3 equivs. of hydrogen in the ammonia are replaced by three different radicals namely by methyl ethyl and phenyl. I have prepared however a similar compound containing amyl instead of methyl whose properties permitted an easier analysis. ACTION OF BROMIDE OF AMYL UPON ANILINE. Amylaniline (AmylQp~enylamine.)-A mixture of aniline and an excess of bromide of amyl when left in contact at the common temperature for some days deposits magnificent crystals of hydro-bromate of aniline.Never have I obtained this salt in larger and more definite crystals; although I have seen it deposited of late from a good many solutions. The mother-liquor of this salt is a mixture of amylaniline and bromide of amyl. If aniline be heated in the water-bath with a very large excess of bromide of amyl the whole is converted into hydrobromate of amylaniline which remains dissolved in the excess of bromide. When prepared without the co-operation of heat the amylaniline may be purified simply by separating the crystals of the aniline-salt and distilling the remaining mixture when the bromide of amyl passes over long before the amyl-base begins to volatilize.If the base has been produced by heating the mixture it is necessary after the excess of bromide has been removed to distil the hydrobromate with potassa. 0.2760 grrn. of oil gave 0*8161grm. of carbonic acid and 0.2560 grm. of water. Analysis led to the formula Amylaniline is a colourless liquid possessing all the family features of the group. It is distinguished at the common temperature by tl very agreeable somewhat rose-like odour rather an unusual property for an arnyl-compound; however it does not deny its origin for on heating the base the disgusting odour:of the fusel- alcohol appears but slightly modified. Amylaniline boils constantly at 258* or 54=3 x l8O higher than ethylaniline. This boiling- DR. HOFMANN point is characteristic inasmuch as the elementary group amyl raises the boiling-point of aniline 44O higher than does the insertion of two equivalents of ethyl whose weight is not very inferior to that of the single amyl- equivalent.The amyl-base forms beautiful rather insoluble salts with hydro- chloric hydrobromic and oxalic acids ; when heated with water they form an oily layer on the surface and crystallize only slowly on cooling they have the peculiar fatty appearance which characterizes the crystalline amyl-compounds. The platinum-salt is precipitated as a yellow mass of an unctuous consistence; it crystallizes but very slowly and usually not before partial decomposition has set in. It is on this account that I have not made an analysis of this compound.ACTION OF BROMIDE OF AMYL UPON AMYLANILINE. Diamylaniline (DiamyZophenylamine).-A mixture of amylaniline and bromide of arnyl solidifies after two days’ exposure to the tem- perature of the water-bath. The new basic compound when separated and purified in the usual manner resembles the preceding base especially with respect to odour. Its salts are so insoluble in water that at the first glance one is almost inclined to doubt the basicity of the substance inasmuch as the oil appears to be perfectly insoluble in dilute hydrochloric and sulyhuric acids. However the oily drops floating in the acid solution are the salts themselves which gradually solidify into splendid crystalline masses having likewise the fatty appearance of amyl-substances.The composition of diamylaniline is represented by the expression ~l CIH2IN-CI2{ c ~=(.lo CIrJ Hll}N* ~ Hl c,o Hl1 c12 H I have established this formula by the analysis of the platinum- compound which is precipitated as an oily mass rapidly solidifying into a brick-red crystalline substance. If an alcoholic solution of the lzydrochlorate be employed it is immediately obtained in the crystalline state. When exposed to the heat of the water-bath this salt fuses without however undergoing any decomposition. Formula C, H,? N. M C1. Pt C1 Diamylaniline boils between 275O and 280O; the small scale upon which I had to work prevented me from determining it more accu- rately. Tt is interesting to see how very little the boiling-point is raised by the introduction of the second equivalent of amyl when compared with the effect produced by the insertion of the first.The same remark applies to the ethylanilines. ON THE VOLATILE ORGANIC BASES. ACTION OF BROMIDE OF ETHYL UPON AMYLANILINE AND OF BROMIDE OF AMYL UPON ETHYLANILINE. Amylethylaniline (Amylethylophenylamine).-It remained now only to analyse a basic compound in which the three equivalents of the ammonia-hydrogen should be replaced by three different radicals. found in amylethylanihe a substance similar in composition to me- thylethylaniline but which by its properties admitted of a rigorous analytical examination. Ainylethylaniline is formed without difficulty by the action of bromide of ethyl upon amylaniline.The mixture having been exposed to the heat of the water-bath the conversion was found to be complete after two days. When purified in the usual way amylethyl- aniline forms a colourless oil boiling at 262O only 4 higher than the amyl-base. The properties of this substance are analogous to those of the other bases. It forms a beautiful crystalline hydro- chlorate and hydrobromate ; the platinum-salt is precipitated in the form of a light orange- yellow pasty mass which rapidly crystallizes. The salt fases at looo. By analysis of the platinum-compound I was cnabled to fix without difficulty the composition of the base which is represented by the formula h substance of exactly the same composition as amylethylaniline may be obtained by the action of bromide of amyl upon ethylaniline.ACTION OF BROMIDE OF ETHYL UPON AMMONIA. After the termination of the experiments which have been detailed in the preceding pages there remained no doubt in my mind respect- ing the deportment which ammonia itself would exhibit when subjected in a similar manner to the influence of bromide of ethyl. I had a right to expect in this reaction the consecutive formation of three alkaloids differing from ammonia by containing respectively one two or the three equivalents of hydrogen replaced by ethyl. Experiment has realized this expectation in a very satisfactory manner. I intend to give here only an outline of the process employed and a short description of the substances obtained. Formution of Elhylamine ~~lhylam~o~ia~ of ethyl acts .-Bromide very slowly onzan aqueous solution of ammonia in the cold.Action however takes place; after the lapse of a week or ten days the solu- tion contains a considerable quantity of a hydrobromate in solution. This hydrobromate is a mixture of the salts of ammonia and ethyla- mine the base discovered by M.Wurtz on decomposing cyanate of 300 DR. HOFMANN ethyl with potassa. The presence of this compound may be readily proved by evaporating the liquid after the separation of the excess of bromide of ethyl to dryness in the water-bath in order to drive off alcohol which might have possibly been formed. On adding potassa-solution to the solid residue an alkaline gas is at once evolved which burns with the pale-blue flame of ethylamine.If an alcoholic solution of ammonia be substituted for the aqueous liquid the decomposition proceeds more rapidly. After twenty-foul* hours a copious crystalline precipitate of bromide of ammonium has been deposited. The mother-liquor contains hydrobromate of ethyl- amine and the base in the free state. The action of bromide of ethyl upon ammonia maybe considerably accelerated by raising the temperature to the boiling-point of water. 1 found it convenient to introduce a concentrated solution of ammo-nia with an excess of bromide of ethyl into pieces of combustion-tube 2 feet in length. These tubes after having been carefully scaled before the blow-pipe were immersed to the height of about half a foot into boiling water. The bromide of ethyl enters at once into lively ebullition rises through the supernatant layer of ammo-nia condenses in the upper part of the tube which is cold and falls down to commence again the same circulation.During this process the bromide of ethyl diminishes rapidly in volume. The reaction may be considered terminated as soon as a quarter of an hour’s ebullition ceases to effect a considerable change in the bulk of the bromide. On opening the tube the solution is found to be either neutral or even of an acid reaction and to contain hydrobromate of ethylamine which may be separated by distillation with potassa .with all the properties enumerated by &I. Wurtz. I have not to add a single word to the accurate description of this distinguished chemist and will here only mention that I have analysed a platinum-salt pre- pared with ethylamine which had been obtained by this process.The production of ethylamine in this reaction is absolutely analo- gous to that of ethylaniline; it is represented by the equation H3N + C Hj Br= C H N. HBr. Formation of Diethylamine ~Die~~yla~n~on~a~ .-On treating an aqueous solutionof ethylamine in the same manner with an excess of bromide of ethyl phenomena of a perfectly analogous character are observed. The reaction however proceeds more rapidly and is termi-nated after a few hours’ ebullition. The aqueous layer which assumes a bright yellow colour deposits acicular crystals on cooling consisting of the hydrobromate of a new base for which I propose the name diethylamine or diethylammonia.This base may be readily separated by distillation with potassa when it passes over in the form of a very volatile and inflammable liquid which is still extremely soluble in ON THE VOLATILE ORGANIC BASES. 301 water and of a powerful alkaline reaction. When dissolved in hydro- chloric acid and mixed with a concentrated solution of bichloride of platinum it yields a very soluble platinum-salt which crystallizes in orange-red grains very different from the orange-yellow leaves of the correspondin8 ethylamine-salt. The analysis of this platinum-salt led to the formula C Hi N. H C1. PtC1 establishing the composition of diethylamine which is represented by the formula C,H,,N= C,H, L*:&l N.Formation of Triethylamine ~Tr~e~h~la~~mo~~a~ .-This arises from diethylamine in the same manner as the latter from ethylamine however unlike the deportment observed in the formation of diethyl-aniline the rapidity of the action increases with the progress of the ethylation. A mixture of a concentrated solution of diethylamine with bromide of ethyl solidifies after a very short ebullition into a mass of beautiful fibrous crystals sometimes of several inches in length being the hydrobroniate of a new base for which I propose the name of triethylamine or triethylammonia. This alkaloid may be readily separated by distillation with potassa when it presents itself in the form of a light colourless powerfully alkaline liquid still very volatile and inflammable and also pretty soluble in water but in a less degree than diethylamine.To fix the composition of triethylamine the platinum-salt was subjected to analysis. This is one of the finest salts I have ever seen. It is extremely soluble in water and crystallizes on the cooling of concentrated solutions in magnificent orange-red rhombic crystals which are obtained of perfect regularity and of very considerable size (half an inch in diameter) even if very limited quantities of solution be employed. The analysis of this salt which slightly fused at 1004 leads to the formula C, H, N. HCI PtCl, and shows that triethylamine may be considered as ammonia in which the 3 equivs. of hydrogen are replaced by 3 of ethyl C, H, N= C 131 N. { "c :::i Although not inclined to expect a further action of bromide of ethyl upon triethylamine after the experiments performed with diethylani- line but hoping to obtain in this series more definite results than DR.HOFMANN the latter had yielded I thought it important to appeal once more to experiment. A mixture of an aqueous solution of triethylamine and bromide of ethyl sealed for this purpose into a tube solidified after two hours’ ebullition. The crystals formed in this reaction had the fibrous aspect of the hydrobromate of triethylamine ; still among the transparent prisms some white opaque granular crystals were observed. To gain more positive information the excess of bromide of ethyl was volatilized and the residue distilled with potassa.The base obtained in this manner converted into a platinum-salt and submitted in this form to analysis gave exactly the percentage of platinum con- tained in the salt of triethylamine. Accordingly the base which had distilled over had evidently not been affected any further by the influence of bromide of ethyl. The appearance however of the opaque crystals* indicates that a second compound is formed whose careful study is necessary for the elucidation of this reaction. I am at present engaged with this part of the inquiry. The action then of bromide of ethyl upon ammonia gives rise to the formation of the following series of compounds H Ammonia. . . . H N={ }N. Ethylamine (Ethylammonia) C €3 N={ }N. c4 H Diethylamine (Dieth ylammonia) Trieth ylamine (Triethylarnmonia) It cannot be doubted for a moment that the same cornpounds will be obtained in the methyl- and amyl-series the first terms in each of these series having been actually prepared by M.Wurtz. Nor is it improbable that arsenietted and phosphoretted hydrogen which as is well known imitate to a certain extent the habits of ammonia when * I have since ascertained that these white opaqne crystals are the hydrobromate of a new base of very remarkable properties. The salt in question may be considered as bromide of ammonium in which all the hydrogen equivalents are replaced by a corre- sponding number of ethyl-equivalents. The reaction is much more powerful if instead of bromide of ethyl the iodide be employed.A mixture of triethylamine and iodide of ethyl solidifies at once to a beautiful crystalline salt containing a base which may be considered as oxide of ammonium in which the four hydrogen-equivalents are re- placed by ethyl. This substance is solid and resembles potassa and soda in its general properties. ON THE VOLATILE ORGANlC BASES. subjected to the action of the chlorides bromides or iodides of the alcohol-radicals will yield a series of arsenietted or phosphoretted bases corresponding to the three classes observed with nitrogen. The highly remarkable bodies discovered by M. Paul Thenard appear to warrant this expectation as far as the phosphorus-series is concerned his compound C6 H p corresponding evidently in the phosphoretted methyl-series to triethyl- amine.I mean to extend these researches to the action of the bromides of the alcohol-radicals on phosphoretted and arsenietted hydrogen RELATION OF THE BASES DERIVED PROM ANILINE AND AMMONIA WITH OTHER GROUPS OF ALKALOIDS. It is impossible to leave the history of these compounds without alluding to some remarkable relations existing between these sub-stances and other bodies of an analogous character whose consti- tution is likely to be illustrated by this line of researches. The basic substances derived from aniline when expressed in formulat exclud- ing any peculiar view respecting the mode in which the elements are arranged present a series which is exhibited in*the following synop- tical table Aniline .. . . . . C, H N Methylaniline . . . . C, H W = C, H N + C,H Ethylaniline . . . . C, HI N = C,,H7N + 2C2H2 Methylethylaniline . C, H, Ri = C, H N -t-3 C H Diethylaniline . . . . C, H15N = C, H,N + 4C,H2 Amylaniline . . . . . C, Hi N = C, H7 N + 5 C H2 Ethylamylaniline . . C, H, N = C, H N +-7 C H Diamylaniline . . . . C, H2 N = C, H N + 1OC H This table shows that the alkaloids in question differ from each other by n C H,? the elementary difference of the various alcohols and their derivatives ; we perceive moreover that the series ascends regularly up to the term C, H N + 5 C H, when the compound C, H N +6 C H is wanting ; lastly we miss the terms C, H N + 8 C H and C1 H N + 9 C H,. The first gap might be easily filled by submitting aniylaniline to the action of iodide of methyl methylamylaniline being in fact C, N = C, H N + 6 C H- The other wanting terms cannot be reached from aniline before some of the missing alcohols are discovered.On examining more closely the formuls of the preceding conspec- tus we find several of them represent basic compounds previously 304 DR. HOFMANN known Chemists are acquainted with the beautiful reaction by which Zinin first linked aniline to benzole through nitrobenzole. c12 1% c12 H N 0 c12 H N* U v + Benzole. Nitrobenzole. Aniline. Researches performed in the most different departments of organic chemistry have gradually elicited a series of carbohydrides differing from benzofe by n C B ; and each of these terms when treated with nitric acid and subsequently exposed to the action of reducing agents has yielded its corresponding base.We are now in the possession of the following series of alkaloids derived from hydro-carbons Benzole . . . . c12H6 Toluole . . C,,H = C1,H + C,H Xylole . . . . Cl HI = c, H $-2 c2 H2 Cumole . . . . C18H,,= C,,H + 3C2H Cymole . . . C20H1P=C,,H + 4C,H Aniline . . . . C,,H7 N Toluidine . . . C14H9N = C,,H7N + C,H2 Xylidine" . . . C, H, N = C1 H N + 2C,H Cumidine? . . . C, H, N = C, H N + 3 C H Cymidinet . . . C, H, N = C, H N + 41 C H On comparing the formula of the bases contained in the last table with those representing the alkaloids derived from aniline by the introduction of' methyl and ethyl we find that they exactly coincide.Toluidine has the same composition as methylaniline ; xylidine cuinidine and cymidine are represented by the same formuh as ethylaniline methylethylaniline and die thylaniline. The question then arises are these substances identical or ax they only isomeric nith each other? I have carefully compared the properties of toiuidine with those of methylaniline and also methylethylaniline with cumidine. These substances are not identical but only iso- meric. The most striking dissimilarity we observe in the characters of toluidine and methylaniline. The former is a beautiful crystal-line compound boiling at 198O yielding difficultly soluble perfectly stable salts with alniost all acids and a splendid orange-yellow platinum-salt which may be boiled without decomposition.We are unacquainted with any process by which we could convert this body into aniline. Methylaniline on the other hand is an oily liquid * Chem. SOC.Qu. J. 111 183. t. On Cumidine a new Organic Base by E. Chambers Nicholson ; Chern. SOC. Qu. J. I 2. $ This compound has been partly investigated by Mr. Noad. ON THE VOLATILE ORGANIC BASES. boiling at 1924 whose salts are distinguished by their solubility and by the facility with which they are decomposed aniline being repro- duced. The platinum-salt even when freshly precipitated is of a pale yellow colour which immediately darkens turning perfectly black after the lapse of an hour. Scarcely less striking is the dissiniilarity of cumidine and methylethylaniline although in this case both substances are liquids.For details I refer to Mr. Nicholson's?; paper on cumidine and to what I have stated about methylethylaniline. The quantity of this substance I had at my disposal was not sufficient for a deterniination of the boiling- point; but if we recollect that ethylaniline boils at 204' and that the introduction of methyl into aniline raised its boiling-point about 104 it is evident that methylethylaniline cannot boil at a temperature much higher than 214*,i. e. eleven degrees below 2254 the boiling- point of cumidine observed by Mr. Nicholson. A detailed account of the properties of xylidine has not yet been published; however I have not the slightest doubt that M. Cahours will find them widely differing from those of ethylaniline.Toluidine xylidine and cumidine resembliiig aniline not only in their physical characters but also in their origin from carbohydrides, evidently belong to the class of alkaloids for which I have provision- ally retained the name amidogen-bases while the basic compounds derived from. aniline are either irnidogen-or nitrile-bases. The difference of properties depends upon a difference in the molecular construction as represented graphically by the following table :-Z )'N = Aniline. Cl H N =Toluidine =C1 H N =Methylaniline = C H N. c,,9 H {G:d }N H =Xylidine =C, Hll N =Ethylaniline Cl H N =Cumidine=C, H13N== The view which I propose in the preceding remarks respecting the constitution of toluidine xylidine and cumidine must as yet be considered as a mere hypothesis.It will not however be diflicult to establish it by facts. The action of bromide of ethyl upon these substances will at once decide this question. These bases when subjected to the influence of the bromides will give rise to the for-' * Chem. SOC. QU.J. I 4 5. VOL III*-NOa XI. x 306 DR. HOPMANN mation of a series of bases similar to those which I have obtained from aniline. I may mention that the deportment of toluidine and cumidine in this respect is now being studied by several of niy pupils. There is no difficulty in introducing 1 equiv. of ethyl into toluidine ;the experiments are however not yet sufficiently advanced to aarm also the insertion of the second equivalent.The alka- loid obtained -by acting with bromide of ethyl upon toluicline is represented by the formula Cl 1% N so that we are now in possession of three alkaloids of exactly the same composition namely ethylotoluidine methylethylaniline and cumidine; and here I cannot but allude to the wonderful variety of isomeric compounds to which a continuation of these researches must necessarily lead. We see at a glance that substances of the formala Cl HI N will also be obtained by inserting 1 equiv. of methyl into xylidine by introducing 2 equivs. of methyl into toluidine or by fixing upon aniline the radical (propyl) belonging to the missing alcohol of pro-pionic acid* (metacetic acid). We thus arrive at six alkaloids having all the same numerical formulze but widely differing in their construction.Cumidine . * Methyloxylidine . Ethylotoluidine Dimethylotoluidine Propylanihe . Methylethylaniline This multiplicity of course augments in the Same measure as we Jp A more appropriate name for metacetic acid proposed by Dumas Malaguti and Leblanc (Compt. Rend. XXV 656) as it is the prst acid of the series C H 0 that exhibits the character of a futty acid i. e. in being separated from solution as a layer of oil and in forming salts with the alkalies that have a greasy appearance. ON THE VOLATILE ORGANIC BASES. asceud upon the scale of organic compounds. FOFevery step the number of possible isomeric bases increases by two so that on arriving at the term diamylaniline c, Hi37 N1 being the last member (vide p.298) in the aniline-series which I have examined we find that its numerical formula actually repre- sents not less than twenty different alkaloids which the progress of science cannot fail to call into existence,-a striking illustration of the simplicity in variety that characterizes the creations of organic chemistry. Not less numerous will be the isomerisms in the series of bases derived by the insertion into ammonia of the alcohol-radicals C Hn+l only as soon as the group of these alcohols themselvea shall be more completely known. Ethylamine is isomeric with dime- thylamine ; diethylamine has the same composition as methyloprcl- pylamine a base containing ethyl and propyl the alcohol-radical in the propyl series as dimethylethylamine and lastly as butylamine.Some chemists are actually inclined to consider as such a volatile alkaloid discovered by Dr. Anderson* among the products of the distillation of animal substances and described by him under thc name of petinine. The formula established by Dr,Anderson is but it is not unlikely that on repeating the analysis an additional hydrogen-equivalent will be found The boiling-point of the eorrl-pound (75O) is very much in favour of butylamine. In a similar manner a great number of bases identical in composi-tion with triethylamine will soon be found,-caproylamine methyla-mylamine ethylobutylarnine dipropylamine and a number of others. In conclusion I append a synoptical view of the various basic com- pounds which I have derived from ammonia; this will exhibit the chief results of these researches perhaps better than would a brief recapitulation of the several facts.* Transactions of the Royal Society of Edinburgh XVI 4. x2 !! w c cx TYPE. AMIDOGEN-B ASES. IMIDOGEN-BASES. NITRILE-BASES. H Diethylaniline c4 Hs U (Diethylophenyla-{C H } X. mine) 42 H x Aniline Methylaniline H Methylethylaniline C H C { C H (Methylethglopheny-{ C H } N. 2 +-(Phen ylamine) lamine) ‘t c, H Hs Diam ylaniline c, H5 2 Amylaniline (Amylophenylamine) {2g (Diamylophenyla-mine) (Ethylamylaniline) C H 1 (Ethylamylophenyl.-( C, €31 N. 2 h mine) c12 Ki Ammonia { ~}N Chloraniline { c-,!(E&)} Ethylochloraniline Diethylochloraniline 0 (Diethylochlorophe-(Amine) (Chlorophenylamine) nylamine) M Ethylobromaniline C v Brornaniline { c.,27€l:) } (Bromophenylamine) N* (E~~~~~mopheny-G 3..- 2 w Nitraniline { c4gHi } N. Ethylonitraniline 0 (Eitrophen ylamine) N. (Ethylonitrophenyla-tz 2+ mine) bl tr Ethylamine Diethylamine Trie thylamine {% $ } N. ’ (Ethylammonia) (Diethylammonia) (Trie th ylammonia) c4 H5 {$ H2 -} ” DR. STENHOUSE ON ARTIFICIAL ALKALOIDS. On the Nitrogenated Principles of Vegetables as the Sources Of Artificial Alkaloids. By Dr. John Stenhouse F.R.S.* It is well known that several organic alkaloids such as Aniline Picoline Yetinine &c. are obtained in the dry distillation of coal.Now as coal is of vegetable origin and these organic alkaloids all contain nitrogen it is evident that they must be ultimately derived from the azotized principles contained in the plants from which the coal has been formed. Hence it appears probable that those proxi- mate vegetable principles which are rich in nitrogen such as vegetable albumen fibrinc legumine &c. will when subjected to destructive distillation yield these same alkaloids or bodies closely resembling them in larger quantities than the coal itself,-inasmuch as the powerful agencies to which that substance has been subjected during the course of its formation must have destroyed a large amount of these azotized principles; and moreover the great bulk of it is made up of non-azotizect matter the residue of woody fibre &c, which can contribute nothing to the forniation of the alkaloids.By con-siderations such as these the author was induced to undertake thc researches of which the following is an abstract. Since vegetable albumen fibrine and caseine are very difficult to obtain in a state of purity the experiments were made with those parts of plants chiefly seeds which contain those principles in the greatest abundance. The first experiment was made with the seeds of the common horse-bean (PhaseoZuscommunis),which contain about 22 per cent of azotized matter. The beans were subjected to dry distillation in cast-iron retorts and the distilled products con-densed by a Lie bi g's condenser A strongly alkaline liquid was obtained containing besides other products acetone wood-spirit acetic acid empyreumatic oils tar a very large quantity of ammonia and several organic bases.The crude product was treated with a considerable excess of hydrochloric acid ; the cleay liquid decanted after the tar had settled to the bottom; the tarry residue treated several times with water containing hydrochloric acid ;the several acid liquids mixed and the whole boiled for a couple of hours. By this treatment the acetone wood-spirit and a large proportion of the empyreumatic oils were either driven off or separated by con- version into resinous matter. The acid liquid was then filtered through charcoal to separate the resins and afterwards mixed with lime or soda and distilled. The distillate contained a large quantity of ammonia together with oily bases the amount of the latter being greatest in the first portions which passed over The oily liquid was separated from the ammoniacal solution by means of a pipette; neutralized with hydrochloric acid whereby the neutral oils mixed with the organic bases were left undissolved and could be separated Phil.Trans. 1850 I 47. DR STENHOUSE ON THE NITROGENATED by filtration and the solution supersaturated with carbonate of soda and distilled in a large retort. The oily bases again passed over together with a quantity of ammoniacal liquid from which they wcre separated by the pipette. An additional quantity was obtained from the weak alkaline liquid which passed over at the latter part of the first distillation by neutralizing that liquid with hydrochloric acid concentrating by evaporation supersaturating with carbonate of soda and again distilling.The oily bases obtained by these operations were again rectified with water to purify them from the resinous matter which still remained ;then repeatedly agitated with strong potash-solution which dissolved out the remaining portions of ammonia and formed a solution which could be separated from the oily liquid by means of a funnel; and lastly dehydrated by repeated agitation during several days with fused hydrate of potash and sub- sequent distillation The first two-thirds of the oily distillate mere colourless; the remainder had a yellowish colour but was likewise rendered colourless by repeated rectification.The boiling-point varied considerably during the distillations showing that the oily liquid obtained was a mixture of different bases. An attempt was therefore made to separate these bases by fractional distillation. The liquid began to boil at 108O C. at which point a small portion of a transparent colourless oil passed over. The thermometer then rose quickly to 120° and from thence ta 1303,at each of which points small portions were collected Between 150° and l5s0 the boiling point remained stationary for a con-siderable time and a considerable quantity of oil then distilled over ; about the same quantity mas collected between 160° and 165O. The boiling-points of the last portions varied between 165O and 220O.The products of these different distillations were again repeatedly rectified and by this means bases were obtained corresponding more closely with those points at which the thermometer remained sta-tionary during the first distillation. These bases though differing considerably in their boiling-points nevertheless resemble each other very closely in their other cha-racters. They are colourless transparent oils with strong refracting power lighter than water and having the peculiar pungent slightly aromatic odour which is characteristic of this class of bodies. The &dour remains on the hands and clothes for a long time and is strongest and most pungent in those bases which are most volatile. They have a hot taste not disagreeable in a state of dilution and resembling that of oil of peppermint.The bases which distil over at low temperatures are tolerably soluble in water,-at any rate more ctoluble than those whose boiling-points are high. They all dissolve in every proportion in alcohol and ether. They exhibit strong alkaline reactions with turmeric and reddened litmus-paper emit copious fumes with hydrochloric acid and neutralize acids per-fectly generally farming crystallizable salts With the chlorides of PRINCIPLES OF VEGETABLES. 31 1 gold platinum and mercury they form double salts soluble in water to nearly the same extent as the corresponding arnmoniacal salts. They precipitate ferric and cupric salts the precipitate in the latter case being easily soluble in excess and yielding a deep blue solution.They do not alter by partial exposure to the air but if exposed to a strong light they turn yellow especially those which boil at the higher temperatures. Nitric acid converts them into yellow resins but without forming carbazotic acid. With hypochlorite of lime they form brownish resiiis but give no trace of aniline. When boiled for a few minutes in a retort they gradually become coloured though the liquid which distilled over was colourless at first. At the close of the distillation a small quantity of resinous matter remained in the retort. The quantity of these bases obtained was not sufficient to yield any very definite analytical results. It is not that the proportion of bases yielded by beans and other seeds is leas than that obtained from animal substances; on the contrary it is equal to that obtained from bones and much greater than that yielded by coal but we have not the advantage-as in the case of bones and coal-of being able to procure the crude oils in large quantity as the waste-products of manufacturing operations ; and consequently the chemist is obliged to distil the seeds on purpose an operation requiring very large apparatus and not conveniently conducted in the laboratory.The base which boiled between 150° and 155O was found by analysis to contain about 74.7 per cent of carbon and 7.98 of hydrogen numbers which nearly correspond with the formula This formula was likewise confirmed by the analysis of the platinum-salt. The cornbination of this base in the anhydrous state with hydrochloric acid is attended with great evolution of heat.The hydrochlorate is very soluble in water and crystallizes in slender prisms. Similar compounds are formed with sulphuric and nitric acid. The platinum-salt crystallizes in four-sided prisms arranged in stars of a deep yellow colour. The gold-salt is very soluble in hot water and crystallizes in pale yellow needles on cooling. The composition of this base approaches very closely to that of ni- cotine C, H N ; but its properties agree more nearly with pico- line the base discovered by Dr. Anderson in coal-tar. It has however a higher boiling-point and is less soluble in water than the latter. It is lighter than water has a peculiar and slightly aromatic odour and a hot taste resembling peppermint; dissolves in every proportion in alcohol and ether ; and remains colourless though kept in an imperfectly stoppered bottle provided it be not exposed to a strong light.It takes fire readily and burns with a bright smoky flame. Three of the bases with which the preceding compound wm accom- DR. STENHOUSE ON THE NITROGENATED panied were likewise analysed and gave the proportions of carbon and hydrogen stated in the following table (a) is the base or rather mixture of bases which boiled between 160Oand 165O; (b) between 165O and 170O; (c) between 200°and 210O. a 6. C. Carbon . 74.08 75.42 75.63 Hydrogen b . 8.06 8.52 8.73 It is rather remarkable that the amount of carbon and hydrogen in these bases or rather mixtures of bases does not differ more considering the great difference in their boiling points.They all form double salts with gold and platinum; those which contain the less volatile bases however crystallize less readil and are more contaminated with resinous matter. Their solubi t'ty in water like- wise diminishes as the boiling-point rises. They all appear to possess equally strong basic properties. More complete investigation was precluded by the great difficulty of procuring these bases in sufficiently large quantity. The next substance subjected to destructive distillation was oif-cake or rather the dried seeds of Linum usitatissimunz from which the fat oil had been expressed. This substance was selected as the type of that numerous class of plants in which the starch of the Grauzinncea! is replaced by oil.Of these the poppy rape and mustard are the best known they are all very rich in albumen. About 2 cwt. of oil-cake was broken into moderate-sized pieces and distilled in the same apparatus as had been used for the beans. The liquid product was smaller in quantity than that obtained from the beans it had an extremely unpleasant odour and contained acetone acetic acid a large proportion of tar and empyreumatic oils and a considerable quantity of ammonia The quantity of organic bases was however not more than one-third of that obtained from the beans. The deficiency may in all probability be attributed to the higher temperature required for the distillation of the oil-cake inasmuch as the volatile alkaloids are decomposed at high tempe- ratures with evolution of ammonia.The bases obtained from the oil-cake were separated and purified by the process already described in the case of the beans. They consisted of a mixture of basic oils different from those yielded by coal or by bones inasmuch as they contained neither aniline nor quinoline. Their odour was different from that of the bases obtained from beans but they resembled the latter closely in their basic pro-perties and in the characters of their Palts. On the whole it seem probable that some of the bases of the two groups may be identical. The grain of wheat (Tri&cum hybernum) which was chosen as the type of the Graminace yielded by dry distillation products very digwent from those previously described-the distillate being strongly acid from thr presence of a large quantity of acetic acid derived PRINCIPLES OF VEGETABLES.from the starch in the grain. Acetone and wood-spirit were likewise present in considerable quantity. The distillate likewise contained a large quantity of ammonia but the proportion of organic bases was very small somewhat less than from oil-cake. These organic bases were very similar to those obtained from the preceding sources but appeared to be more volatile they contained neither aniline nor quinoline. Feat from the moors near Glasgow when subjected to destructive distillation yielded a distillate which was nearly neutral and contained a large quantity of acetic acid besides acetone and wood-spirit.The acid distillate was mixed with hydrochloric acid and boiled to drive off the acetone and wood-spirit-whereupon as the liquid cooled the tarry matter separated as a semi-solid crust on the surface and could be easily removed. The clear liquid was then supersaturated with carbonate of soda and distilled. An ammoniacal liquid passed over mixed with a considerable quantity of oily bases which were separated as in former cases. The quantity of these bases was much greater in proportion to the ammonia thau in the distillate from the linseed-cake probably because they distilled over at a lower tenipe- rature. They strongly resembled the preceding groups and contained neither aniline nor quinoline.Wood-The rough distillate of beech oak ash and other hard woods obtained in the manufacture of pyroligneous acid (for which purpose the stems and thicker branches are exclusively employed) was found to contain scarcely a trace either of ammonia or of organic alkaloids. Hence it would appear that the stems of trees are almost destitute of azotized matter presenting in that respect a striking contrast to peat. This difference may perhaps throw some light on the origin of coal. For coal when subjected to destructive distil- lation yields a large quantity of azotized products and must therefore have been formed from vegetable matter rich in nitrogen. Hence the theory which regards it as produced by the submersion of peat- bogs appears to be more probable than that which attributes it to the submersion of trees.It is true that the bases derived from peat are not the same as those from coal; but on the other hand it mast be remembered that plants of Merent families when submitted to dry distillation yield different groups of volatile bases thus plants of the indigo tribe yield ammonia and aniline ;tobacco-leaves yield ammonia an& nicotine &c. &c. Hence the difference in the distil- lation-products of peat and coal may perhaps be ascribed to the difference between the plants from which the coal-strata have been formed and those of which the peat-mosses of the present day are composed. Formatim of Organic Bases $-om Azotized ?Tegetable and Animal Xlcbstances otherwise than by Destructive Distillation 1.By treating them with alkaline Zeys.-A quantity of beans was introduced into a large distillatory apparatus and boiled with caustic I)R STENHOUSE OF THE NITROGENATED soda. The beans were soon converted into a slimy dark-coloured pulp which frothed up considerably and rendered the distillation very troublesdme. By carefully rectifying the crude distillate a clear strongly alkaline liquid was obtained which contained a large quantity of ammonia a sinall quantity of an aromatic oil having an agreeable odour and a notable quantity of organic bases. These bases were separated in the same manner as in former instances. Theywere similar to those obtained by destructive distillation but the author could not positively decide as to whether they were identical.Oil-cake yielded similar results and hence we may conclude that the same would be the case with the azotized portions of other plants when similarly treated. The liver of an ox boiled with caustic soda yielded a strongly alkaline liquid from which a small quantity of oily bases was obtained but not sufficient to determine their nature. 2. By the aid of Sulphuric acid-A small quantity of beans was digested with dilute sulphuric acid care being taken not to let the action proceed so far as to cause the evolution of sulphurous acid. The acid liquid supersaturated with carbonate of soda and distilled yielded an ammoniacal distillate containing organic bases similar to those already described. Hence it is probable that animal substances similarly treated would likewise yield organic bases.3. By Putrt$action.-A quantity of horse-flesh previously ex-hausted of soluble matters by long-continued boiling was moistened with water and left to itself in a warm place for a month. When it had reached a somewhat advanced state of putrefaction it mas treated with water containing hydrochloric acid as long as anything was dissolved out and the acid liquid concentrated filtered super- saturated with carbon of soda and distilled. An alkaline liquid passed over from which by repeated rectification with caustic soda a light oily fluid was obtained consisting of several organic bases mixed together. It had an aromatic and not unpleasant odour was very soluble in water strongly alkaline and formed crystalline salts with acids.Contrary to expectation however it was found to be quite free from aniline. The quantity of organic bases obtained from this source was not so great as might have been expected ;being much less than that produced by destructive distillation. Perhaps however if the putrefaction were suffered to go on for a longer time-till in fact the flesh should be completely decomposed- the quantity of bases thereby produced might be greater than that resulting from destructive distillation. Considering indeed the very gradual nature of the putrefactive process it may possibly be found the most advantageous that can be adopted for the preparation of these alkaloids on tlie large scale. 4. Orgarzic bases from Guano.-A quantity of Peruvian guano very dry of pale yellow colour and emitting a comparatively feeble odour was distilled with water and an excess of quick lime.The PRINCIPLES OF VEGETABLES. distillate which was strongly ammoniacal was saturated with hydro- chloric acid evaporated to one-third of its bulk then supersaturated with carbonate of soda and re-distilled. The liquid which passed over contained a small but appreciable quantity of oily bases which appeared to be more easily soluble in water than those obtained from the preceding sources. Bases from Lycopodium-A quantity of lycopodium (the repro- ductive matter of lycopodiaceze) boiled with strong caustic soda evaporated to dryness and distilled yielded a considerable quantity of ammonia and a basic oil which was but slightly soluble in water and had a pecnliar very penetrating odour like that of the borage plant.It neutralized acids completely but in other respects did not resemble the bases previously mentioned. The same oil was obtained by destructive distillation of the plant ; towards the end of the operation however another oily liquid was obtained having an odour more like that of the bodies previously described. This result with lycopodium affords another instance of the fact that plants of different natural families yield different groups of volatile organic bases. Bases from Pteris aquiZina.-The stems and leaves of the com-mon fern (P. apuiZina) being subjected to distillation yielded a very alkaline liquid containing ammonia and a tolerably large quantity of organic bases thc odour of which was very much like that of the bases obtained froni beans and from linseed.From the facts above detailed it seems to follow that ‘I Whenever ammonia is produced in Zurge quantity from complex animal or vegetable substances it is always accompanied by the formation qf volatile organic buses.” If therefore researches similar to the above are actively prosecuted and especially if the seeds and leaves of the various genera of plants are subjected to similar processes it seems not unreasonable to expect that the number of volatile organic alkaloids will ere long be considerably increased. Another inference which seems to follow from these experiments is that the nitrogenous principles of these plants viz.vegetable albumen caseine fibrine &c. though very analogous to the corre-sponding principles of the animal kingdom are not identical with them; otherwise the products of decomposition would be the same. In conducting the destructive distillation of animal and vegetable substances it is important to operate at as low a temperature as possible; for if the heat be raised too high the organic bases are almost totally destroyed ammonia being then the only alkaline product. It is highly probable that in many cases the ammonia obtained in the distillation of animal and vegetable substances is really derived from the destruction of orgaiiic bases; for these organic bases are more coxplex in their structure than ammonia; and the most stable of them when passed once or twice through a tube filled with red-hot charcoal are almost entirely converted into MR JOULE ON THE that alkali; and even when organic bases are strongly heated in contact with potash or soda or when their aqueous solutions are simply boiled for any length of time they always undergo partial decomposition ammonia being an invariable product.On the Mechanical Equivalent of Meat. By J. P.Joule F,C.S.* Opinions have long been divided between two hypotheses respect- ing the nature of heat,-the one regarding it as a peculiar substance the other as the cffect of motion among material particles. The latter hypothesis appears to be most in accordance with the develop- ment of heat by friction-a phenomenon first accurately investigated by Count Rumford who showed that the very great quantity of heat excited in the boring of cannon could not be ascribed to a change in the calorific capacity of the metal and thence concluded that it was due to the motion in the particles communicated by the borer.cc It appears to me,” he remarks extremely difficult if not I‘ impossible to form a distinct idea of anything capable of being excited and communicated as the heat was communicated in these experiments except it be rnotion.”T In the same paper Count Rumfordmakes an estimate of the quantity of niechanical force required to produce a certain amount of heat-showing in fact that the friction produced by the power of one horse acting for two hours and a half will generate heat sufEcient to raise 26-58 pounds of water from 32O to 212O F.Now the power of a horse is estimated by Watt at 33,000 foot-pounds,$ and there- fore if continued for two hours and a half will amount to 4,950,000 €oat-pounds. Hence it is easily calculated that the heat required to raise a pound of water lomust be equivalent to the force repre-sented by 1034 foot-pounds. This estimate of the force is rather too high no account having been taken of the heat communicated to the containing vessel or of that which was lost by dispersion during the experiment. About the end of the last century Sir Humphry Davy showed that when two pieces of ice were rubbed together in vacuo part of them was melted although the temperature of the receiver was kept below the freezing-point.This experiment was the more decisive in favour of the doctiine of the immateriality of heat inasmuch as the heat-capacity of ice is much less than that of water. It was there- fore with good reason that Davy drew the inference that <<the immediate cause of heat is motion and the laws of its communi- * Phil. Trans. 1850,I 61. 1. Phil. Trans. (abridged) XVIII 286. $ A foot-pound is the force expended in raising a pound-weight one foot high in a minute. MECHANICAL EQUIVALENT OF HEAT. cation are precisely the same as the laws of the communication of motion.”* Dulong discovered the remarkable fact that :-‘cEqual volumes of all elastic fluids at the same temperature and under the same pressure if compressed or dilated suddenly to the same fraction of their volume disengage or absorb the same absolute quantity of heat .”-/-This law is of the utmost importance in the development of the theory of heat inasmuch as it shows that the calorific effect is under certain conditions proportional to the force expended.The researches of Dr. Faraday on the relations between light heat electricity magnetism and chemical force all tend to show that the so-called imponderables are merely exponents of different kinds of force. Mr. Grove and M. Mayer have likewise advocated the same views. The earlier investigations of Mr. Joule in connection with this matter are described in his Memoir as follows (‘My own experiments in reference to the subject were com-nienced in 1840,in which year I communicated to the Royal Society niy discovery of the law of the heat evolved by voltaic electricity a law from which the immediate deductions were drawn 1st.That the heat evolved by any voltaic pair is proportional c&mis paribus to the electromotive force;$ and 2nd. That the heat evolved by the combustion of a body is proportional to the intensity of its affinity for oxygen. I thus succeeded in establishing relations between heat and chemical affinity. In 1843 I showed that the heat evolved by magnetic electricity is proportional to the force absorbed and that the force of the electromagnetic engine is derived from the force of chemical affinity in the battery or force which would otherwise be evolved in the form of heat.From these facts I considered myself justified in announcing that the quantity of heat capable of increasing the temperature of a pound of water by one degree of Fahrenheit’s scale is equal to and may be converted into a mechanical force capable of raising 838 lbs. to the perpendicular height of one foot.”$ In a subsequent paper read before the Royal Society in 1844 I endeavoured to show that the heat absorbed and evolved by the rarefaction and condensation of air is proportional to the force evolved and absorbed in those operations. (1 The quantitative relation between force and heat deduced from these experiments is almost identical with that derived from the electro-magnetic experiments just referred to and is confirmed by the experiments of M.Seguin on the dilatation of steam.”fi “From the explanation given by Count Rumford of the heat * Elements of Chemical Philosophy p. 94. $ Phil. Mag. XIX 225. .f. Mem. Acad. Sec. X 188. 5 Phil. Mag. XXIII 441.’ 11 Phil Mag. XXVI 375,379. TI Compt Rend XXV 421. Mk. JOULE ON TBE arising from the friction of solids one might have anticipated %w a matter of course that the evolution of heat would also be detected in the friction of liquid and gaseous bodies. Moreover there were many facts such as for instance the warmth of the sea after a few days of stormy weather which had long been attributed to fluid friction. Nevertheless the scientific world pre-occupied with the hypothesis that heat is a substance and following the deductions drawn by Pictet from experiments not sufficiently delicate have almost unanimously denied the possibility of generating heat in that way.The first mention so far as I am aware of experiments ill which the evolution of heat from fluid friction is asserted was in 1842 by M. &layer,* who states that he has raised the temperature of water from 12"to 13O C. by agitating it without however indi- cating the quantity of force employed or the precautions taken to seciire a correct result. In 1843 I announced the fact that 'heat is evolved by the passage of water through narrow tubes,'? and that each degree of heat per pound of water required for its evolution in this way a mechanical force represented by 770 foot-pounds.Subsequently in 18452 and 1847,$ I employed a paddle-wheel to produce the fluid friction and obtained the equivalents of 781.5 782.1 and 787*6respectively from the agitation of water sperm-oil and mercury." Results so closely in accordance with one another and with those previously derived from experiments with elastic fluids and the electro-magnetic machine indicated beyond doubt the existence of an equivalent between force and heat; but still it appeared of the highest importance to obtain that relation with greater accuracy. With this view fresh experiments were made of which the following is an abstract The apparatus employed for producing the friction of water con- sisted of a brass paddle-wheel furnished with eight sets of revolving arms working between four sets of stationary vanes.This revolving apparatus was firmly fitted into a copper vessel in the lid of which were two necks one for the axis to revolve in without touching the other for the insertion of a thermometer. A similar apparatus but made of iron of smaller size and having six rotatory and eight sets of stationary vanes was used for experiments on the friction of mercury. The apparatus for the friction of solids consisted of a vertical axis carrying a bevelled cast-iron wheel against which a fixed bevelled wheel was pressed by means of a lever; the wheels were enclosed in a cast-iron vessel filled with mercury the axis passing through the lid. In all these arrangements motion was given to the axis by the descent of leaden weights suspended by strings from the axes of two wooden pulleys these axes being supported on * Ann Ch.Pharm. XLI. -t. Phil. Mag. XXIII 442. $ Phil. Mag. XXVIII 205. 5 Phil Mag. XXXI 1'13i afso Compt Rend XXV,309. MECHANICAL EQUIVALENT OF HEAT. 319 friction-wheels. The pulleys were connected by fine twine passing round their circumferences with a wooden roller which by means of a pin could be easily attached to or removed from the axis of the frictional apparatus. The mode of experimenting was as follows :-"!he temperature of the frictional apparatrxs having been ascertained and the weights wound up with the assistance of a stand provided for the purpose the roller was fixed to the axis. The precise height of the weights above the ground having been determined by means of graduated vertical slips of wood the roller was set at liberty and allowed to revolve till the weights reached the floor.The roller was then removed to the stand the weights wound up again and the friction renewed. After this had been repeated twenty times the experiment was concluded with another observation of the temperature of the apparatus. The mean temperature of the apartment was determined by observations made at the commencement middle and determina- tion of each experiment. Previously to or immediately after each experiment an observation was made of the effect of radiation and conduction to or from the atmosphere in depressing or raising the temperature of the friction apparatus.In these trials the position of the apparatus the quan- tity of liquid contained in it the time occupied the method of observing the thermometers the position of the experimenter-in short everything with the exception of the apparatus being at rest- was the same as in the experiments in which the effect of friction was observed. In the experiments with water a correction was made for the quantities of heat absorbed by the copper vessel and the paddle- wheel ; and in the experiments with mercury and cast-iron the heat- capacity of the whole apparatus was determined by ascertaining the heating. effect which it produced on a known quantity of water in which it was immersed. In all the experiments corrections were likewise made for the velocity with which the weights came to the ground and for the quantity of force expended in overcoming friction and the rigidity of the strings.The thermometers with which the temperatures were observed had their tubes calibrated and graduated by Regnault's method and were capable of indicating a difference of temperature as small as &of a degree of Fahrenheit's scale. Friction of water.-A force of 6067.14 foot-pounds was found to raise the temperature of 9747'0.2 grains of water by OO.563209 which is equivalent to 7*842299pounds of water raised lo. Con-seauentlv 6067*114= 773.64 foot-pounds, 7-842299 is the force which according to this determination is equivalent to loFahr. in a pound of water. 320 MR. JOULE ON THE MECHANICAL EQUIVALENT OF HEAT.Friction of mercury.-In one set of experiments with the mercurial apparatus a force of 6077,939 foot-pounds was found to generate heat sufficient to raise the temperature of 7'85505 pounds of water one degree ;the equivalent thence deduced is G077'939 = 773.62 7.85504 A second series of experiments with the same apparatus but smaller weights gave for the equivalent 2100*272= 776.303 2.70548 Friction of cast-iron.-A force of 59800955 foot-pounds generated heat suffcient to produce a rise of loin 7.69753 pounds of water. The equivalent thence deduced is Another series of experiments with smaller weights gave In these last experiments the friction of the cast-iron wheels produced a considerable vibration in the frame-work of the apparatus as well as a loud sound; it was therefore necessary to make allowance for the quantity of force expended in producing these effects.The following table contains a summary of the equivalents determined as above; in the fourth column the results are given with the correction necessary to reduce them to a vacuum. Material employed. Equivalent in air. Water . . . . 773.640 Equivalent i.n 'oacuo. 772*692 Mean. 772.692 Mercury . . 773.762 ¶I . . . 776.303 Castiron . . . . 776.997 JY . . . 774880 '176*045774.930 774*987 The equivalent 772.692 is regarded by the author as the most correct; but even this he observes is probably a little too high because even in the friction of fluids it is impossible entirely to avoid vibration and the production of a slight sound.The conclusions to be deduced froin all the experiments above- described are 1. Thut the quantity of heat produced by the friction of bodies whether solid or liquid is always proportional to the force expended. 2. That the quantity of heat capable of increasing the temperature of n pound of water (weighed in vacuo and faken at between 55O and 60°) 6y loFAHR., requiresfGr its evolution the expenditure of a mechanical force represented by the fall of 772 Ibs. through the space of onefoot

 

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