214 



CHEMISTRY. 



aided by heat; but this being submitted to 

 action of hydrogen at the highest possible tem- 

 perature, or by the induced electric spark, no 

 union occurs. If, however, the electric arc is 

 caused to pass between electrodes composed 

 of this carbon, and in an atmosphere of hydro- 

 gen, the conditions of union are secured ; ace- 

 tylene begins at once to be produced, and 

 continues to be so as long as the conditions are 

 maintained : the product being carried over and 

 absorbed in an ammoniuretted solution of pro- 

 tochloride of copper, is liberated afterward by 

 action of hydrochloric acid. With this acety- 

 lene Berthelot next succeeds in combining 

 hydrogen so as to give olefiant gas (0 4 H 4 ) ; 

 from this he proceeds to common or other al- 

 cohols, as above ; from the alcohols, ethers are 

 obtained by the well-known methods ; and so 

 on. Thus is started, directly from the ele- 

 ments, and capable of being extended indefi- 

 nitely, a chain of compounds hitherto regard- 

 ed as belonging exclusively to the class of 

 products of organic or vital action. 



Among other syntheses recently accomplish- 

 ed, are those consisting in the addition of the 

 element hydrogen to certain compounds the 

 hydrogen being set free during oxidation of 

 sodium-amalgam introduced into water. In 

 this manner, Wurtz has transformed aldehyde 

 into alcohol, by mixing the former in water 

 and introducing the amalgam named. Friedel, 

 by means of the nascent hydrogen set free by 

 the sodium-amalgam, has converted other alde- 

 hydes, as the benzoic and valerianic, into their 

 corresponding alcohols. Kekule, through union 

 of H a , has transformed fumaric into succinic 

 acid ; and Linnemann has effected the trans- 

 formation of sugar into mannite. 



The practicability of producing artificially 

 the albuminous or protein substances, having 

 been suggested some years since by Prof. T. S. 

 Hunt, in accordance with his theory regarding 

 those substances as amids or nitryls, and being 

 also rendered probable through the researches 

 of Laurent, Gerhardt, and others, certain 

 chemists have given much attention to experi- 

 ments having this end in view. Up to the 

 present time, however, nothing very decisive 

 has been effected in this direction. As, how- 

 ever, by action of ammonia on chloracetic acid, 

 glycocol (C 4 II, NO 4 ) is obtained, Volhard, 

 by substituting in this reaction methylamine 

 (C a H 5 N) for ammonia, has effected the forma- 

 tion of sarcosine, a compound which Liebig had 

 obtained as a product of the decomposition of 

 Icreatine the latter being found in the juice of 

 flesh and in the urine. 



VI. DIALYSIS. Professor Thomas Graham 

 has been conducting through several years 

 a series of researches in one line of connection 

 between chemistry and physical science. The 

 most important of the results attained by him 

 have been given to the world in his papers on 

 "Diffusion," "Osmose," and finally that on 

 "Liquid Diffusion applied to Analysis." Of 

 these it has been remarked that, while probably 



the author could not himself have foreseen the 

 value of the conclusions he was to reach, there 

 is nevertheless a logical sequence in the sub- 

 jects and the developments they have afford- 

 ed ; and that, since Davy startled the scientific 

 world with the announcement of the metallic 

 bases of the alkalies, the science of chemistry 

 has scarcely received any other contributions 

 so pregnant with important results. The prin- 

 ciples arrived at in the investigation last named, 

 in fact, serve to show more distinctly than ever 

 before the close connection of chemical phe- 

 nomena, not only with the physical, on one side, 

 but also with the physiological, on the other. 

 As a mark of appreciation of the entire series, 

 the Eoyal Society in 1862 awarded to Prof. 

 Graham the Copley medal. 



The mode of analysis by diffusion Graham 

 denotes more briefly by the term Dialysis. 

 Essentially, the method is one which serves to 

 separate one from another certain substances, 

 usually compounds, by taking advantage of the 

 different rates at which such substances are 

 capable of diffusing through moist gelatine-like 

 films or other partitions, or upward through 

 water or viscid masses. A simple method of 

 effecting this consists in placing the mixture 

 of bodies to be separated in a cylindrical glass 

 vessel 5 or 6 inches deep, and so carefully in- 

 troducing water above as not to disturb or 

 intermix them. After a few days, the upper 

 Btrata of water can be successively drawn off 

 by means of a pipette into as many different 

 vessels ; and analysis of these shows what sub- 

 stances have become most diffused, and in 

 what quantities. For practical purposes, the 

 " hoop dialyser" is usually to be preferred ; this 

 consists of a vessel in shape of a sieve, 8 to 12 

 inches across and 3 inches deep, the rim of gutta 

 percha, the bottom of parchment paper. Plac- 

 ing in this a mixed solution of gum and sugar, 

 with pure water enough to cover the bottom 

 to the depth of half an inch, let the vessel float 

 upon a larger quantity of pure water : in 24 

 hours, all the sugar will have passed through 

 the membrane, and so free from gum that the 

 solution is scarcely rendered turbid by basic 

 acetate of lead, while on evaporation it yields 

 crystallized sugar. Like the sugar, all bodies 

 capable of distinct crystallization in some 

 degree, diffuse with comparative readiness, 

 though at quite different rates, through liquids, 

 gelatinous masses, and most porous septa : of 

 these bodies, good examples are the chlorides, 

 sulphates, and other salts of metallic bases. 

 On the other hand, bodies having little or no 

 tendency to crystallize, and which incline in 

 presence of water to assume the form or ap- 

 pearance of a jelly, of which starch, vegetable 

 gums, caramel, tannin, albumen, a number of 

 hydrated metallic peroxides (as silica), etc., are 

 examples, possess comparatively little or no 

 power of diffusion under like circumstances. 

 Professor Graham accordingly divides bodies 

 generally, in view of their behavior in this 

 respect, into the two classes of 1, the crystal- 



