C. Voegtlin and C. P. Sherwin 147 
transform all the silver into AgCl. The latter was filtered off 
and the filtrate was carefully evaporated to a small volume 
in vacuo at low temperature in order to protect ‘the amino- 
purines from the destructive action of the nitric acid. The 
remaining solution was made alkaline with ammonia in order 
to precipitate the guanine. The guanine settled out as a gelat- 
inous mass, which was redissolved in dilute HCl and repre- 
cipitated with NH,OH. After drying this precipitate, an amor- 
phous white mass remained. 
The filtrate from the original guanine precipitate was treated 
with CO: in order to remove the adenine. This method did not 
prove satisfactory, so the solution was slightly acidified with 
HCl and treated with a saturated solution of picric acid in 
water. After some standing the resulting yellowish brown pre- 
cipitate was filtered off and recrystallized from water. It gave 
all the tests for adenine picrate. 
The silver acetate purine fraction was treated in the same 
way and corresponding amounts of guanine and adenine picrate 
were obtained. 
The total amount of adenine picrate from both fractions after 
recrystallization amounted to 1.141 gm. (0.72 gm. from AgNO3; 
0.421 gm. from Ag acetate) or 0.498 gm. of adenine. The total 
guanine collected (recrystallized) was 1.09 gm. 
Identification of Guanine. 
The guanine recovered from the purine fraction after repre- 
cipitation from acid solution by NH3 and drying was a white 
amorphous powder. It was converted into its different salts as 
follows. | 
Guanine Sulfate—A fraction of a gram of the powder was 
dissolved in dilute H2,SOs (warm) and allowed to stand over 
night on ice. The following morning long white rhombic needles 
had formed. The crystals were filtered off, dried zn vacuo-to 
constant weight, and then a melting point was taken. The 
crystals lose their water of crystallization at 118-120°. No 
definite melting point was obtained. 
Guanine Picrate——0.3 gm. of guanine was dissolved in dilute 
HCl and treated with a saturated aqueous solution of picric acid. 
