708 PHYSIOLOGICAL CHEMISTRY. 



plished by the urinometer, which is a small hydrometer indicating spe- 

 cific gravity from zero (or 1000) to 60 (or 1060). (See Fig. 73.) As 

 the temperature influences the density of liquids, a urinometer can 

 only give correct results at a certain degree of temperature, which is 

 generally marked upon the instrument. 



Composition. Urine is chiefly an aqueous solution of urea and 

 inorganic salts, containing, however, always some uric acid, coloring-, 

 and other organic matters. 



Urine also contains gaseous constituents, amounting to about 16 

 per cent, by volume ; these gases are chiefly carbon dioxide (88 per 

 cent.) and nitrogen (11 per cent.), with very little oxygen (1 per cent.). 



The quantity of urine passed in a day also varies widely, an adult 

 discharging from 500 to 2300 c.c. in twenty-four hours ; a normal 

 average quantity is about 1000 to 1500 c.c. (about 36 to 54 ounces). 

 The quantity of total solids contained in this urine varies from 55 to 60 

 grammes (840 to 920 grains), and about one-half of this quantity is urea. 



As many of the .so-called pathological constituents of urine are 

 actually present in minute quantities in normal urine, it is difficult to 

 make an absolute distinction between physiological and pathological 

 constituents. Below is given a working classification of the more 

 important constituents, regarding as normal those whose presence may 

 readily be shown by clinical tests. Accordingly, indican, for ex- 

 ample, is placed with the normal bodies, while acetone is placed with 

 the pathological substances, though both are normally present in 

 small amounts. 



Normal constituents. 

 Urea. 

 Ammonia. 



Nitrogen as 



Creatinine. 



Uric acid. ( Xanthine bases. 

 Other bodies < Allantoin. 



( Hippuric acid. 

 Chlorine as chlorides. 



Phosphorus as phosphoric acid. ( ( 1 ) Inorganic (K, Na, etc.). 



Sulphur as { Neutral sul P lmr - (2) Organic (ethereal). 



(Oxidized sulphur = sulphates: \ Indole (indican). 

 Sodium, } Skatole. 



Potassium, I . . [ Phenol. 



Calcium, Combined with acids. 



Magnesium, I 

 Oxalic acid. 

 Pigments. 

 Enzvmes. 



