730 URINE. 



The quantity of calcium and magnesium is determined according to 

 the ordinary well-known methods. 



Iron occurs in the urine only in small quantities, and, as it seems from the 

 investigations of KUNKEL, GIACOSA, ROBERT and his pupils, it does not exist 

 as a salt, but as an organic combination in part as pigment or chromogen. The 

 reports in regard to the iron present seem to show that the quantity ranges from 

 1 to 11 milligrams per liter of urine (MAGNIER, GOTTLIEB, ROBERT and his pupils). 

 JOLLES found as an average for twelve persons 8 milligrams of iron in twenty- 

 four hours, while HOFFMANN, NEUMANN and MAYER 1 found lower results an 

 average of' 1.09 and 0.983 milligrams. The quantity of silicic acid is ordinarily 

 stated to amount to about 0.3 p. m. 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 gi eater 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 ordinarily cal- 



1 Runkel, cited from Maly's Jahresber., 11; Giacosa, ibid., 16; Robert, Arbeiten 

 des Pharm. Inst. zu Dorpat, 7; Magnier, Ber. d. deutsch. chem. Gesellsch., 7; Gott- 

 lieb, Arch. f. exp. Path. u. Pharm., 26; Jolles, Zeitsctr. f. anal. Chem.. 36; Hoffmann, 

 Zeitschr. f. anal. Chem., 40; Neumann and Mayer, Zeitschr. f. physiol. Chem., 37. 



