THE NITEOGEN OF PEOCESSED FEETILIZEBS. 9 



solution contained sufficient to give a yellow precipitate, when a drop 

 was removed and tested with a solution of barium hydroxide. The 

 solution was then filtered, and the separation of the three hexone 

 bases was earned out according to the method of Kossel and Kut- 

 schor.° The solution was cooled to 40° C. and saturated with finely 

 powdered barium hydroxide. The precipitate which was formed was 

 collected and stirred up in a mortar with solid barium hydroxide, 

 when it was again filtered off and washed with barium-hydroxide 

 solution. This precipitate contains the silver salts of histidine and 

 arginine, whilo the filtrate contains the lysine. 



Lysine. — The above filtrate was acidified with sulphuric acid and 

 freed from silver with hydrogen sulphide. Lysine was precipitated 

 from this solution as the phosphotungstate, and the free base was 

 obtained by decomposing this salt with barium hydroxide. From a 

 concentrated solution of the base, which was strongly alkaline in 

 reaction and which showed no tendency to crystallize on standing, 

 the picrate salt was prepared. This compound showed the solubility, 

 characteristic crystalline appearance, and properties of lysine picrate. 6 

 When taken up in boiling water and allowed to crystallize slowly, 

 it formed in rather large yellow prisms, but when in small amount 

 the crystals assumed a fernlike appearance. The lysine was 

 further identified by the preparation from the picrate of the hydro- 

 chloride salt, C 6 H 14 2 N 2 .2 HC1, and the platinum chloride salt, 

 C 6 H 14 2 N 2 .H 2 Pt C1 6 + C 2 H 5 OH. c 



The silver precipitato which would contain the arginine and histi- 

 dine was suspended in water acidified with dilute sulphuric acid and 

 broken up with hydrogen sulphide. The silver sulphide was filtered 

 off, the sulphuric acid was removed with barium hydroxide solution, 

 and after filtering the solution was made slightly acid with nitric acid. 

 Silver nitrate solution was added until a test drop with barium 

 hydroxide gave a yellow precipitate. Histidine was completely pre- 

 cipitated as the silver salt by the careful addition of barium hydroxide 

 solution. The precipitate was washed with barium hydroxide solu- 

 tion until the washings ceased to give a test for nitrates. 



Histidine. — The histidine silver was suspended in water acidulated 

 with sulphuric acid and treated with hydrogen sulphide. The pro- 

 cedure described by Kossel and Kutscher was followed, and the 

 histidine was finally separated as the dihydrochloride salt. The 

 method of obtaining this compound and the characteristic crystal- 

 line form of the dihydrochloride salt d are sufficient to establish its 

 identity as histidine. 



a Zeit. physiol. Chem., 31, 1G6 (1900). 



b Kossel, Zeit. physiol. Chem., 25, ISO (1898); 26, 586 (1899). 



cHedin, Zeit. physiol. Chem., 21, 299 (1895). 



dSchwantke, Zeit. physiol. Chem., 29, 492 (1900); Kossel, ibid., 22, 182 (1896). 



63138°— Bull. 158—14 2 



