THE NITROGEN OF PROCESSED FERTILIZERS. 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 carried out according to the method of Kossel and Kut- 
scher." Tlie solution was cooled to 40° C. and saturated with finely 
powdered barium hydroxide. The precipitate which was formed was 
collected and stuTcd 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, while the filtrate contains the lysine. 
Lysine. — The above fiiltrate 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.^ 
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, C6H14O2N2.2 HCl, and the platinum chloride salt, 
CeH.AN^.H^Pt Cle + CA OH.'^ 
The silver precipitate 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 sUghtly 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 dihydro chloride salt. The 
method of obtaining this compound and the characteristic crystal- 
line form of the dihydrochloride salt ^ are sufficient to estabUsh its 
identity as histidine . 
oZeit. physiol. Chem.,31, 1G6 (1900). 
b Kossel, Zeit. jghysiol. Chem., 25, 180 (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 
