9 ANIMAL CHEMISTRY LECTURE IV. 



oxygen we obtain only the monocarbon compound C0 2 , by its 

 combustion in hydrogen we obtain the dicarbon compound C 2 H 2 , 

 which is separated from the excess of hydrogen by transmission 

 through an ammoniacal solution of the white or inferior chloride 

 of copper, whereby it is retained in the form of cuprous acetylide 

 C 2 HCu. This compound is thrown down as an abundant bright 

 red precipitate, and, by treatment with warm hydrochloric acid, 

 is decomposed with liberation of acetylene gas, thus : 



Cupr-acetylide Chlorhyd. acid Cuprous chlor. Acetylene 



C 8 HCu + HC1 = CuCl + C s H a 



Acetylene is characterised by the extreme luminosity with which 

 it burns. You observe the great opacity and whiteness of its 

 flame, and the large amount of light afforded by it in proportion 

 to its bulk, when compared, for instance, with the flame of 

 ordinary coal gas, of which, indeed, acetylene is a constituent, 

 though only to a small extent. By hydrogenising his cuprous 

 acetylide with a mixture of zinc and ammonia, instead of treating 

 it with hydrochloric acid, Berthelot produced olefiant gas or 

 ethylene, from which, by indirect hydration with sulphuric 

 acid, he afterwards obtained alcohol, as I have already de- 

 scribed. 



(94.) Now, among other animal products, alcohol occurs as a 

 residue of tyrosine, a compound to which I shall refer more par- 

 ticularly in my next lecture ; and, as I have before observed, 

 of taurine, which is producible in the following manner: 

 Under certain circumstances, the residues of alcohol and sul- 

 phuric acid combine with one another to form isethionic acid, 

 easily convertible into chlorethyl-sulphurous acid C 2 H 5 C1SO 3 , 

 by means of pentachloride of phosphorus. This chloride is re- 

 transformable into its hydrate or isethionic acid C 2 H 5 (HO)SO 3 , 

 by the action of water, while both the chloride and the hydrate 

 are transformable into the amide or taurine C 2 H 5 (H 2 N)S0 3 ,* by 



* These formulae are not meant to express the assumed internal mole- 

 cular arrangement of the three bodies, but only their positively ascertained 

 mutual relationship. 



