266 PHYSIOLOGY AT THE FARM. 



The urine of the horse has a peculiar unpleasant odour, a 

 bitter saline taste with a sweetish after-flavour. Being al- 

 lowed to rest, it deposits a mixture of carbonate of lime and 

 carbonate of magnesia, which blackens on being burnt. Its 

 specific gravity varies between 1.030 and 1.050. It has an 

 alkaline reaction, and effervesces with acids. When left in con- 

 tact with atmospheric air it acquires a deeper colour, and by 

 evaporation deposits a fresh quantity of earthy carbonates 

 combined with an animal matter. After evaporation it leaves 

 about 0.05 of residue, 4-5ths of which is soluble in alcohol; 

 the undissolved portion is principally carbonate of soda. The 

 alcoholic solution affords crystals first of chloride of sodium, 

 then of hippurate of soda in brown plates. When the resi- 

 due, after the evaporation of the alcohol, is dissolved in water, 

 hydrochloric acid throws down hippuric acid from the solution. 

 After having evaporated the urine of the horse, and thrown 

 down urea by nitric acid, and saturated the mother liquor with 

 an alkali, according to Fourcroy and Vauquelin, a small quan- 

 tity of solid reddish fat is obtained. This substance has an 

 acrid taste, is volatile along with the vapour of water, is very 

 soluble in alcohol, and combines with acids. The same fatty 

 substance, according to these chemists, is to be obtained from 

 the urine of herbivorous animals in general, and is the cause of 

 its smell and colour. Their analysis of the urine of the horse is 

 as follows : 



Urea, ..... 



Hippurate of soda (urobenzoate), . 



Carbonate of soda, .... 



Chloride of potassium, 



Carbonate of lime, .... 



Water, with a little mucus and acid fat, 



100.0 



The absence of uric acid and of the phosphates is common 

 * Berzelius : "Trait6 de Chimie,' traduit par Esslinger, tcme vii. p. 396. 



