URINE. 81 



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, 323.25 



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

 i. 022, there are contained 22 X 2 -33 = S 1 - 2 ^ grains of solid matter. 



Organic Constituents of Urine. Urea is one of the most important 

 of the organic constituents of the urine, and is present to the extent of from 

 2.5 to 3.2 per cent. Urea is a colorless, neutral substance, crystallizing to 

 four-sided prisms terminated by oblique surfaces. When crystallization is 

 caused to take place rapidly, the crystals take the form of long, silky 

 needles. Urea is soluble in water and alcohol; when subjected to pro- 

 longed boiling it is decomposed, giving rise to carbonate of ammonia. In 

 the alkaline fermentation of urine, urea takes up two molecules of water 

 with the production of carbonate of ammonia. 



The average amount of urea excreted daily has been estimated at about 

 500 grains. As urea is one of the principal products of the breaking up of 

 the albuminous compounds within the body, it is quite evident that the 

 quantity produced and eliminated in 24 hours will be increased by any 

 increase in the amount of albuminous food consumed, by a rapid destruc- 

 tion of albuminous tissues, as is witnessed in various pathological states, in- 

 anition, febrile conditions, fevers, etc. A farinaceous or vegetable diet will 

 diminish the urea production nearly one-half. 



Muscular exercise when the nutrition of the body is in a state of equi- 

 librium does not seem to increase the quantity of urea. 



Seat of Urea Formation. As to the seat of urea formation, little 

 is positively known. It is quite certain that it preexists in the blood and is 

 merely excreted by the kidneys. It is not produced in muscles, as even 

 after prolonged exercise hardly a trace of urea is to be found in them. 

 Experimental and pathological facts point to the liver as the probable organ 

 engaged in urea formation. Acute yellow atrophy of the liver, suppurative 

 diseases of the liver diminish almost entirely the production of urea. 



