3 ANIMAL CHEMISTRY LECTURE II. 



into water and its nitrogen liberated in the gaseous state, together 

 with the nitrogen of the nitrous acid, thus : 



Ammonia Nitrous acid Water Nitrogen 



H 3 N + HN0 4 = aH 3 + N, 



Accordingly, when hippuric acid is treated with nitrous acid, 

 its ammoniacal residue is similarly destroyed by the nitrous acid, 

 while the two other residues are left combined with one another 

 in the form of benzoglycolic acid. Hence, hippuric acid has 

 been represented as a combination of ammonia, with benzoglycolic 

 acid, which is itself susceptible of decomposition into its constituent 

 benzoic and glycolic acids. (Strecker.) 



a. Benzoic acid C 7 H 6 0^ 



-0. Glycolie acid C a H 4 3 



C 9 H I0 5 

 - Water H z 



Benzoglycolic acid C 9 H 8 4 



(38.) I am not aware of any reagents capable of destroying the 

 benzoic residue, and so leaving the glycolic and ammoniacal resi- 

 dues in combination with one another ; but on boiling hippuric 

 acid with acids or alkalies, the benzoic may be separated from 

 the other two residues, which are thus obtained in the form of 

 glycocine, or sugar of gelatin. Hence hippuric has been, 

 and is now, commonly regarded as a compound of benzoic acid 

 with glycocine, which is itself resolvable into glycolic acid and 

 ammonia. (Dessaignes.) 



j8. Glycolic acid C a H 4 3 



7. Ammonia H 3 N 



C a H 7 N0 3 

 - Water H z 



Glycocine C 3 H 5 N0 3 



