206 A Manual of Veterinary Physiology. 



urine of horses at rest than of those at work, which is 

 explained by the considerable amount of potassium excreted 

 with the sweat. 



Sodium only exists in the urine in small quantities, which 

 is due to the fact that very little sodium is found in vege- 

 table food. In the chapter on 'The Constituents of the 

 Organism ' the question of sodium in the feeding of 

 herbivora is discussed (p. 19). 



The Sulphuric Acid in its organic combination has been 

 dealt with previously. The inorganic sulphur is combined 

 with the alkalies : work does not influence its production ; 

 about I oz. is excreted daily. The origin of the urinary 

 sulphates is from the decomposition of the proteids of the 

 tissues. 



Chlorine is supplied by the chlorides of the food. The 

 proportion of chlorine in the food of herbivora is not very 

 high ; the amount secreted by horses is between § ozs. to 

 1 oz. per diem, and this, united to the small amount of 

 sodium present, equals a daily excretion of 85£ grains of 

 common salt. 



Phosphoric Acid, though existing largely in food, such as 

 oats, passes off almost wholly by the alimentary canal. 

 Sometimes only traces are to be found in the urine ; at. 

 others the amount is marked, but never considerable. Work 

 does not influence its production. 



Ammonia, — I believe that free ammonia exists in the 

 urine of herbivora. It may be that, owing to the amount 

 of mucin, the urine has undergone ammoniacal fermenta- 

 tion in the bladder; but it is certain that perfectly fresh 

 urine gives marked evidence of the presence of free ammonia. 

 On standing a short time, especially in summer weather, 

 the urea decomposes and carbonate of ammonia is largely 

 formed. 



The following table, published in my papei on 'The 

 Urine of the Horse,' gives the mean composition of this fluid, 

 which lias been compiled from a considerable number of 

 analyses :* 



* Proceedings Royal Sooiety, No. 283. 



