44 ANIMAL CHEMISTRY LECTURE II. 



We next come to hippuric acid, which, as I have already 

 said, contains a residue of benzoic acid and a residue of glyco- 

 cine, which itself contains residues of glycolic acid and ammonia. 

 This is succeeded by the two principal acids of the bile, the first 

 of which, or glyco-cholic acid, contains a residue of cholic 

 acid and a residue of glycocine, and consequently differs only 

 from hippuric acid in containing a residue of cholic acid C 24 H 40 5 , 

 instead of a residue of benzoic acid C 7 H6O 2 . The other bile acid, 

 known astauro-cholic acid, contains a residue of cholic acid 

 and a residue of taurine, which already contains residues of 

 ammonia and isethionic acid, the latter body further containing a 

 residue of alcohol and a residue of sulphuric acid, thus : 



Cholic 

 Tauro-cholic 



Taurine -I ( Alcohol 



(Ammonia 

 Isethionic -I 



Sulphuric 



(43.) The last compound which I propose to bring under your 

 notice to-day is kreatine, a beautiful crystalline body, as you 

 may perceive, from the unusually fine specimen lent me by Dr. 

 Hugo Miiller. This body, which exists largely in the juice of 

 flesh, and also, though to much less amount, in human urine, is 

 represented by the formula C 4 H 9 N 3 O 2 . Under the influence of 

 caustic baryta it absorbs water, with transformation into sar- 

 cosine and urea, the residues of which pre-exist in the kreatine, 

 thus : 



Urea Sarcosine Water Kreatine 



CH 4 N a O + C 3 H 7 NO a - H a O = C 4 H 9 N 3 O a 



The urea, as I have already observed, contains residues of 

 carbonic acid and ammonia, and the sarcosine residues of glycolic 

 acid and methylamine, which last body further contains a re- 

 sidue of ammonia and a residue of wood-spirit, as shown in this 

 diagram : 



