EXCRETION. 421 



gastric glands and the consequent liberation of bases which are ex- 

 creted in the urine. The phosphoric acid which enters into com- 

 bination with sodium and potassium bases is a product of tissue 

 metabolism. 



The specific gravity is about 1.020, though it varies from 1.015 

 to 1.025. It will diminish, other things being equal, with increased 

 consumption of water and diminished activity of the skin; it will be 

 increased of course by the opposite conditions. 



The quantity of urine excreted in twenty-four hours varies from 

 1200 to lyoo c.c. Amounts both above and below these are fre- 

 quently passed from a variety of causes. 



The odor of the urine is characteristic and due to the presence of 

 aromatic compounds. 



COMPOSITION OF URINE. 



Water, 1500.00 c.c. 



Total solids, 72.00 grams. 



Urea, _ 33.18 



Uric acid, (urates), 0.55 " 



Hippuric acid, hippurates, 0.40 " 



Kreatinin, xanthin, hypoxanthin, guanin, ammo-) 



nium salts, pigment, etc. / 



Inorganic salts: sodium and potassium sulphates, "] 



phosphates, and chlorids; magnesium and cal- | 



cium phosphates, j* 27.00 " 



Organic salts: lactates, acetates, formates in small | 



amounts, J 



Sugar, a trace 



Gases, nitrogen, and carbonic acid. 



The estimation of total urinary solids in any given sample of 

 urine is frequently a matter of clinical interest. This may approxi- 

 mately be attained by multiplying the last two figures of the specific 

 gravity by the coefficient of Haeser or Chnstison, 2.33. me result 



expresses the total solids in 1000 parts: e. g., urine with a specific 

 gravity of 1.020 would contain 20X2.33, or 46.60 grams of solid 

 matter per 1000 c.c. If the amount passed in twenty-four hours be 

 1500 c.c., the total solids would amount to 69.9 grams. 



The Water of the Urine. The amount of urinary water and its 

 ratio to the solid constituents will vary with the amount consumed 

 and the activity of the skin and lungs. In summer the foods, liquid 

 and solid, remaining the same, the, guant'itv of water in the urine js^ 

 diminished in consequence of increased activity of skin and lungs 

 and the ratio of water to solids decreased. ( In winter the reverse 

 conditions obtainl The food remaining the same, the consumption 

 of large quantities of water hastens at least the removal of end- 

 products from the tissues and thus increases the urinary solids. 



Urea is the most abundant of the organic constituents of the 

 urine and is present to the extent of from 2 to 3 per cent. It is a 



