3 78 EXCRETION 



soldiers the average daily output of urine through a period of about five 

 months was for the students 1,215 c - c - w i tn average specific gravity of 1020, 

 and for the soldiers 1,042 c.c. with specific gravity of 1023. 



GENERAL CHEMICAL COMPOSITION OF THE URINE. 



Water 967 



Solids: 



Urea 14.230 



Other nitrogenous crystalline bodies : -^ 



Uric acid, principally in the form of alkaline Urates, a trace 



only free ( fi 



Kreatinin, Xanthin, Hypoxanthin f 



Hippuric acid 



Mucus, Pigments, and ferments J 



Salts: 



Inorganic: 



Principally Sulphates, Phosphates, and Chlorides of So-^j 

 dium and Potassium, with Phosphates of Magnesium 



and Calcium, traces of Silicates ! R 



Organic: 



Lactates, Hippurates, Oxalates, Acetates, and Formates, 



which appear only occasionally . J - 33 



Sugar a trace sometimes. 



Gases (nitrogen and carbonic acid principally). 



Reaction. The normal reaction of the urine is slightly acid. This 

 acidity is due to carbonic acid and to acid phosphate of sodium, and is less 

 marked soon after meals. After standing for some time the acidity increases 

 from a kind of acid fermentation, due in all probability to the presence of 

 mucus and fungi, and acid urates or free uric acid is deposited. After a 

 time, varying in length according to the temperature, the reaction becomes 

 strongly alkaline from the change of urea into ammonium carbonate, due 

 to the presence of one or more specific micro-organisms (micrococcus urece). 

 In the process of fermentation the urea takes up two molecules of water, a 

 strong ammoniacal and fetid odor appears, and there are deposits of triple 

 phosphates and alkaline urates. This does not occur unless the urine is 

 freely exposed to the air, or, at least, until air has had access to it. 



In most herbivorous animals the urine is alkaline and turbid. The 

 difference depends not on any peculiarity in the mode of secretion, but on 

 the difference in the food on which the two classes of animals subsist; for 

 when carnivorous animals, such as dogs, are restricted to a vegetable diet, 

 their urine becomes pale, turbid, and alkaline like that of herbivorous 

 animals, while the urine voided by the Herbivora, e.g., rabbits, fed for 

 some time exclusively upon animal substances, presents the acid reaction and 

 other qualities of the urine of Carnivora, and its ordinary alkalinity is again 

 restored only OP the substitution of a vegetable for the animal diet. Human 

 urine is not usually rendered alkaline by vegetable diet, but it becomes so 



