770 URINE. 



0.1046 to 0.2594 grams per day on a mixed diet. Traces of hydrogen peroxide 

 also occur in the urine. 



The gases of the urine are carbon dioxide, nitrogen, and traces of 

 oxygen. The quantity of nitrogen is not quite 1 vol. per cent. The 

 carbon dioxide varies considerably. In acid urines it is hardly one-half 

 as great as in neutral or alkaline urines. 



IV. THE QUANTITY AND QUANTITATIVE COMPOSITION OF URINE. 



The quantity and composition of urine are liable to great variation. 

 The circumstances which under physiological conditions exercise a great 

 influence are the following: the blood-pressure, and the rapidity of the 

 blood-current in the glomeruli. The quantity of urinary constituents, 

 especially water in the blood; and, lastly, the condition of the secretory 

 glandular elements. Above all, the quantity and concentration of the 

 urine depend on the quantity of water which is introduced into the blood 

 or which leaves the body in other ways. The excretion of urine is increased 

 by drinking freely or by reducing the quantity of water otherwise removed ; 

 and it is decreased by a diminished ingestion of water or by a greater loss 

 of water in other ways. Ordinarily in man just as much water is elimi- 

 nated by the kidneys as by the skin, lungs, and intestine together. At 

 lower temperatures and in moist air, since under these conditions the 

 elimination of water by the skin is diminished, the excretion of urine 

 may be considerably increased. Diminished introduction of water or 

 increased elimination of water by other means as in violent diarrhoea or 

 vomiting, or in profuse perspiration greatly diminishes the amount of 

 urine excreted. For example, the urine may sink as low as 500-400 cc. 

 per day in intense summer heat, while after copious draughts of water 

 the elimination of 3000 cc. of urine has been observed during the same 

 time. The quantity of urine voided in the course of twenty-four hours 

 varies considerably from day to day, the average being ordinarly cal- 

 culated as 1500 cc. for healthy adult men and 1200 cc. for women. The 

 minimum elimination occurs during the early morning between 2 and 4 

 o'clock; the maximum, in the first hours after waking and from 1-2 

 hours after a meal. 



The quantity of solids excreted per day is nearly constant, even though the 

 quantity of urine may vary, and it is quite constant when the manner of living 

 is regular. Therefore the percentage of solids in the urine is naturally in inverse 

 proportion to the quantity of urine. The average amount of solids per twenty- 

 four hours is calculated as 60 grams. The quantity may be calculated with approx- 

 imate accuracy from the specific gravity if the second and third decimals of this 

 factor be multiplied by HASER'S coefficient, 2.33. The product gives the amount 

 of solids in 1000 cc. of urine, and if the quantity of urine eliminated in twenty- 

 four hours be measured, the quantity of solids in twenty-four hours may be 

 easily calculated. For example, 1050 cc. of urine of a specific gravity 1.021 was 



