216 THE URINE. 



phosphoric acid in terms of P 2 O 5 is 7.72 grammes, while the corre- 

 sponding amount of acid phosphates is 6.736 grammes after correct- 

 ing as above indicated. The percentage of the acid phosphates, as 

 compared with the total P 2 O 5 , would then be 87.2, as is seen from 

 the calculation : 



7.72 : 100 : : 6.736 : x. 



Chemical Composition of the Urine. A general idea of the 

 chemical composition of the urine and the quantitative variations of 

 the individual components may be formed from the accompanying 

 table, which I have constructed from numerous analyses made in 

 my laboratory. The individuals from which the urine was obtained 

 were all adults, and in their general mode of life, as regards diet, 

 exercise, etc., followed the common habits of the average American 

 city-dweller. 



ANALYSIS OF URINE. 



Water 1200-1700 grammes. 



Solids 60.0 



Inorganic solids 25.0 -26.0 



Sulphuric acid (H 5 SO 4 ) 2.0-2.5 



Phosphoric acid (P 2 O 3 ) 2.5-3.5 



Chlorine (NaCl) 10.0 -15.0 



Potassium (K 2 Oj '. 3.3 



Calcium (CaO) 0.2-0.4 



Magnesium (MgO) 0.5 



Ammonia (NH 3 ) 0.7 



Fluorides, nitrates, etc 0.2 



Organic solids 20.0 -35.0 



Urea 20.0 -30.0 



Uric acid . . . 0.2-1.0 



Xanthin bases 1.0 



Kreatinin : 0.05- 0.08 



Oxalic acid 0.05 



Conjugate sulphates 0.12- 0.25 



Hippuric acid 0.65- 0.7 



Volatile fatty acid 0.05 



Other organic solids 2.5 



THE INORGANIC CONSTITUENTS OF THE URINE. 



The inorganic constituents of the urine represent the excess of 

 mineral salts which find their way into the blood from the digestive 

 tract, or which develop within the body during the decomposition 

 of the albumins. As has been indicated, they are eliminated 

 through the specific activity of the renal epithelial cells, so that 

 the composition of the blood always remains constant. We accord- 

 ingly find that the ingestion of large amounts of food invariably 

 leads to an increased elimination of salts, and that conversely 

 smaller amounts are excreted when smaller amounts are ingested. 

 This is true more especially of the chlorides and the phosphates, 

 while the sulphates are largely referable to albuminous destruction, 

 and are only ingested as such in minimal quantities. As the chlo- 

 rides, moreover, are far more abundant in food-stuffs than the phos- 



