CALCIUM AND MAGNESIUM. 769 



than 1 gram, and of this amount f is magnesium and J calcium phos- 

 phate. This statement, as found by RENWALL and GROSS, is not correct, 

 or at least is not true in general, as they found more calcium than mag- 

 nesium in the urine. LONG and GEPHART l obtained similar results. 

 In acid urines the mono- as well as the dihydrogen earthy phosphates 

 are found, and the solubility of the first, among which the calcium salt 

 CaHPO4 is especially insoluble, is particularly augmented by the presence 

 in the urine of dihydrogen alkali phosphates and sodium chloride (OTT 2 ) . 

 The quantity of alkaline earths in the urine depends on the composi- 

 tion of the food. The lime-salts absorbed are in great part excreted 

 again into the intestine, and the quantity of lime-salts in the urine is 

 therefore no measure of their absorption. The introduction of readily 

 soluble lime-salts or the addition of hydrochloric acid to the food may 

 therefore cause an increase in the quantity of lime in the urine, while 

 the reverse takes place on adding alkali phosphate to the food. Accord- 

 ing to GRANSTROM starvation in rabbits or the introduction of food which 

 yields an acid ash and causes an acid urine produces the same effect as 

 the introduction of acid. The observation of DE JAGER S is significant, 

 namely, he found that the partaking of CaSCU and to a higher degree 

 of MgSO4 causes an increase in the urine ammonia and of acid. Noth- 

 ing is known with certainty in regard to the constant and regular change 

 in the elimination of calcium and magnesium salts in disease, and in these 

 conditions the excretion is chiefly dependent upon the diet and the forma- 

 tion and introduction of acid. 4 



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 it does not exist as a 

 salt, but as an organic combination of a colloidal nature. The earlier reports in 

 regard to the iron present seem to show that the quantity ranges from 1 to 11 

 milligrams per liter of urine. HOFFMANN, NEUMANN and MAYER found lower 

 results an average of 1.09 and 0.983 milligrams and according to recent determi- 

 nations of WOLTER and REICH 5 the quantity is about 1 milligram. The quantity 

 of silicic acid is ordinarily stated to amount to about 0.3 p. m. H. SCHULZ 6 found 



1 Renwall, Skand. Arch. f. Physiol., 16; Gross, Biochem. Ccntralbl., 4, 189; Long 

 and Gephart, Journ. Amer. Chem. Soc., 34. 



2 Zeitschr. f. physiol. Chem., 10. 



8 Granstrom, Zeitschr. f. physiol. Chem., 58; de Jager, Bioch. Zeitschr., 38. 



4 See page 758, Albu and Neuberg, 1. c., and E. Zak, Ueber Harn bei Lungenent- 

 ziindung, Wien. klin. Wochenschr., 21. ' 



6 Kunkel, 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, Zeitschr. f. anal. Chem., 36; Hoff- 

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

 Chem., 37; Wolter, Bioch. Zeitschr., 24; Reich, ibid., 36. 



8 Pfluger's Arch., 144. 



