768 URINE. 



MANN'S experiments this was not possible, still in recent experiments of 

 JANNEY 1 it was possible, by introducing large quantities of sodium citrate, 

 which was burned in the body into carbonate, to reduce the ammonia 

 elimination to very insignificant quantities. 



The detection and quantitative estimation of ammonia used to be performed 

 according to the method suggested by SCHLOSING. The principle of this method 

 is that the ammonia from a measured amount of urine is set free by lime-water 

 in a closed vessel and absorbed by a measured amount of N/10 sulphuric acid. 

 After the absorption of the ammonia the quantity is determined by titrating the 

 remaining free sulphuric acid with a N/10 caustic-alkali solution. This method 

 gives low results, and in exact work we must proceed as suggested by BORLAND. 2 



The recent methods for estimating the ammonia are all based upon 

 the distillation of the ammonia, after the addition of lime, magnesia, 

 or alkali carbonate, at low temperatures either by the aid of vacuum 

 (NENCKI and ZALESKI, WURSTER, KRUGER, REICH and SCHITTENHELM 

 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 3 25 cc. of the urine are placed in a distillation-flask with about 

 10 grams of NaCl and 1 gram of Na2COs, 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. Instead of alkali carbonate a one-half normal solution of barium 

 hydrate in methyl alcohol can be used. According to FOLIN'S 4 method, 

 25-50 cc. of the urine are treated in a wash-bottle with 1-2 grams soda and 

 8-10 grams sodium chloride and some petroleum, in order to prevent 

 frothing, and then a current of air is passed through and this passed 

 through a second . wash-bottle containing N/10 acid. It has also been 

 suggested (RONCHESE, MALFATTI and others) to determine the ammonia 

 by the formol titration. This method is based upon the fact that an 

 ammonium salt yields hexamethylentetramine and free acid with for- 

 maldehyde according to the equation 4NH4Cl+6HCOH = C6Hi2N4 

 -J-6H2O+4HC1. This acid is determined by titration after the addition 

 of formol. FOLIN 5 also recently suggested a method for the quantitative 

 colorimetric estimation of ammonia by the use of NESSLER'S reagent. 



Calcium and Magnesium occur in the urine chiefly as phosphates. 

 The quantity of earthy phosphates eliminated daily is somewhat more 



1 N. Janney, Zeitschr. f. physiol. Chem., 76, which also contains the literature. 



2 Pfluger's Arch., 43, 32. 



3 Zeitschr. f. physiol. Chem., 39; Schaffer, Amer. Journ. of Physiol., 8, which contains 

 the literature. Henriques and S6rensen, Zeitschr. f. physiol. Chem., 64. 



4 Folin, Zeitschr. f. physiol. Chem., 37, and Journ. of biol. Chem., 8; Steel, ibid., 8. 

 6 Ronchese, see Maly's Jahresber., 38, 321; Malfatti, Zeitschr. f. anal. Chem., 47; 



H. Bjorn-Andersen and M. Lauritzen, Zeitschr. f. physiol. Chem., 64; L. de Jager, 

 ibid., 62; Folin and Maccallum, Journ. of biol. Chem. ,.11. 



