The Urine. 199 



Urine consists of : 



Water. 



r Nitrogenous end products : urea, uric acid, hippuric 



acid, creatin, creatinin. 



Organic matter- Aromatic compounds : benzoic acid, ethereal sulphates 



I of phenol, cresol, etc. 



'Colouring matter and mucus. 



I Sodium, potassium, calcium, magnesium, combined 



\ with chlorine, sulphuric and phosphoric acids. 



The Reaction of the urine of herbivora is alkaline, the 

 alkalinity being due to carbonate of potash. The urine of 

 all vegetable feeders is alkaline, owing to the combustion 

 in the system of the acid potash salts, the potash appearing 

 in the urine as carbonate, and producing considerable 

 effervescence on the addition of an acid. The nature of 

 the food influences the reaction, for it is stated that the 

 urine of the horse may be rendered acid by feeding entirely 

 on oats. A considerable quantity of the alkalinity present 

 in stale horses' urine is due to the exceedingly rapid change 

 which occurs in it on standing, leading to the breaking up 

 of part of the urea and the formation of ammonia carbonate. 

 The fixed alkalinity of the urine for the twenty-four hours, in 

 the horse is equivalent to the excretion of between 45 grains 

 to 60 grains of potassium oxide. 



The following remarks apply solely to the urine of the 

 horse ; what is known of this excretion in other animals 

 will be spoken of subsequently. 



The Specific Gravity of urine varies considerably : the 

 mean of a large number of observations was 1036 ; the 

 highest registered was 1050, and the lowest 1014. 



The Quantity of urine for the 24 hours is about 8| pints ; 

 working horses excrete less, owing to the loss by the skin, 

 etc. 



In estimating the urinary constituents for the 24 hours, 

 they should always be calculated on the total amount 

 passed, and the sample examined should be a portion of 

 the 24 hours" fluid. Without the total urine it is impos- 

 sible to estimate the changes in the system. For clinical 

 purposes, where the presence or absence of a substance is 



