CALCIUM AND MAGNESIUM. 729 



and SCHAFFER) or by the aid of a current of air (FOLIN) and then collect- 

 ing it in a standard acid. 



According to the methods suggested by KRUGER, REICH and SCHITTEN- 

 HELM l 25 cc. of the urine are placed in a distil] ation-flask with about 

 10 grams of XaCl and 1 gram of Xa 2 CO 3 , and this distilled at 43 C. 

 and a pressure of 30-40 millimeters Hg with the aid of an air-pump. 

 Alcohol is added to prevent foaming. The ammonia is absorbed in 

 N/10 acid contained in a PELIGOT tube surrounded by ice-water, and 

 when the distillation is finished the acid is retitrated, making use of 

 rosolic acid as indicator. In regard to details, see the original publica- 

 tions. SCHAFFER'S method is practically the same STEEL arid GIES 

 have raised objections to FOLIN' s method (passing air through the urine), 

 as they found low results in the presence of large quantities of magnesium 

 phosphate in the urine. MALFATTI 2 has recently suggested a method 

 based upon an entirely different principle. 



Calcium and magnesium occur in the urine chiefly as phosphates. 

 The quantity of earthy phosphates eliminated daily is somewhat more 

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

 phate. This statement, as found by RENWALL and GROSS, 3 is not correct, 

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

 nesium in the urine. 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 CaHPO 4 is especially insoluble r is particularly augmented 

 by the presence in the urine of dihydrogen alkali phosphates and sodium, 

 chloride (On 4 ). The quantity of alkaline earths in the urine depends 

 on the composition 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. According to GRANSTROM 5 starvation in rabbits or the intro- 

 duction of food which yields an acid ash and yields an acid urine produces 

 the same effect as the introduction of acid. Nothing is known with 

 certainty in regard to the constant and regular change in the elimina- 

 tion of calcium and magnesium salts in disease, and in these conditions 

 the excretion is chiefly dependent upon the diet and the formation and 

 introduction of acid. 6 



1 Zeitschr. f. physiol. Chem,, 39; Schaffer, Amer. Journ. of Physiol., 8, which con- 

 tains the literature. 



2 Steel and Gies, Journ of biol. Chem., 5; Malfatti, Zeitscjir. f. anal. Chem., 47. 



3 Renwall, Skand. Arch. f. Physiol., 16; Gross, Biochem. CentralbL, 4, 189. 



4 Zeitschr. f . physiol. Chem., 10. 

 *IUd., 58. 



B See Albu and Neuberg, 1. c., and Zak, Wien. klin. Wochenschr., 21. 



