74 HUMAN PHYSIOLOGY. 



COMPOSITION OF URINE. 



Water 967. 



Urea ; 14.230 



Other nitrogenized crystalline bodies, uric acid, prin- ~] 

 cipally in the form of alkaline urates. 



Creatin, creatinin, xanthin, hypoxanthin. ,- 



Hippuric acid, leucin, tyrosin, taurin, cystin, all in j 

 small amounts, and not constant. 



Mucus and pigment. 

 Salts : 



Inorganic, principally sodium and potassium sul- ") 

 phates, phosphates and chlorides, with magnesium j 

 and calcium phosphates, traces of silicates and 

 chlorides. 8 -'35 



Organic: lactates, hippurates, acetates, formates, 

 which appear only occasionally. 



Sugar a trace. 



Gases (nitrogen and carbonic acid principally). 



1000.00 



The Average Quantity of the principal constituents excreted in 24 

 hours is as follows : 



Water 52 fluid oz. 



Urea 512.4 grains. 



Uric acid 8.5 



Phosphoric acid 45.0 



Sulphuric acid 31.11 



Inorganic salts 3 2 3- 2 5 



Lime and magnesia 6.5 



To Determine the amount of solid matters in any given amount of 

 urine, multiply the last two figures of the specific gravity by the coefficient 

 of Hseser, 2.33 ; e. g., in 1000 grains of urine having a specific gravity 

 1.022, there are contained 22 X 2 -33 = 51.26 grains of solid matter. 



The Elimination of the urinary constituents is accomplished by the 

 two processes of filtration and secretion. 



i. By Filtration the water and mineral salts are removed from the 

 blood ; this takes place, for the most part, in the Malpighian corpuscles, 

 by the process of osmosis. The amount of these constituents eliminated 

 varies with the pressure of blood in the renal arteries. All of the agencies 

 which increase the general blood pressure increase the quantity of urine. 



Season. In summer, while the capillary vessels of the skin are dilated, 

 and perspiration is abundant, there is a diminished blood pressure, and a 

 consequent diminution in the amount of urine ; in winter the reverse takes 

 place. 



