690 ANIMAL PHYSIOLOGY. 
Hippuric acid (Benzoyl-Glycin, or Benzoyl-amido-acetie Acid). 
CoH»NOs. 
* This acid abounds in the urine of the herbivora, being derived, proba- 
bly, from some benzoic residue in the food (hay). It occurs in only 
small quantity in the urineof man. It may be obtained in prisms, solu- 
ble in boiling water and in alcohol. 
Phenol (Carbolic acid). CsHs.OH. 
This compound occurs under the same circumstances as indol in the 
alimentary tract, and may be extracted from the faeces and the urine. 
Slightly soluble in water, it readily dissolves in alcohol and ether. 
Tyrosin. C.HiuNOs. 
This substance, the molecular constitution of which is still in doubt, 
is certainly an aromatic body, which may be obtained in needles ; solu- 
ble in hot water, acids, and alkalies, but insoluble in alcohol and ether. 
Tyrosin occurs with leucin in the decomposition of proteids, and 
abundantly in the natural and artificia] digestion of the proteids, by 
trypsin. A substance greatly resembling it has been made artificially, in 
the laboratory, by a synthesis. 
