334 J. HOWARD MUELLER 



Separation into two fractions by means of silver sulphate and baryta 



Because of the presence of considerable histidine in the crude 

 HgS04 precipitate, as shown by color reactions, a purification 

 of the fraction by means of Ag2S04 and baryta suggested itself. 

 As will be seen, this resulted in a simple method for the separa- 

 tion of the activating material into the two fractions. The 

 method is not attended by the uncertainty of the HgS04 frac- 

 tional precipitation, and leads quite easily to a quantitative 

 separation. The Ag2S04 precipitate, which contains the factor 

 which will hereafter be referred to for the sake of bre\'ity as 

 "X," corresponds to the second HgS04 precipitate, while the 

 filtrate from the Ag2S04 fraction contains the "Y" as does also 

 the filtrate from the second HgS04 precipitation. 



Aminoids are precipitated as described above with HgS04, 

 and after freeing the precipitate from Hg and from H2S, a hot 

 saturated solution of Ag2S04 (or AgNOa if the nitrate radicle 

 will not interfere with further work) is added until an excess is 

 present as shown by testing a drop with a drop of Ba(0H)2. 

 Cold saturated Ba(0H)2 solution is then added until precipita- 

 tion is complete and the precipitate filtered or centrifuged off. 

 The filtrate is freed from Ag with H2S and Ba with H2SO4, and 

 is concentrated to an equivalent of 10 per cent original aminoids 

 over a low flame, and is found to contain the Y fraction, entirely 

 free from X. The Ag2S04 precipitate contains the X fraction 

 together with traces of Y, and it must be reprecipitated in the 

 same way to free it entirely from Y. The Ag and Ba are re- 

 moved as usual, the H2S boiled out, the solution cooled and more 

 Ag2S04 and Ba(0H)2 added as in the first precipitation. This 

 precipitate, when freed from Ag and Ba is found to contain the 

 active X, quite free from Y. The test for active X or Y is of 

 course made in the usual way, using decolorized infusion and 

 glucose salt, together with a preparation known to contain Y or 

 X as the case may be. 



Further purification of X fraction 



The Agi,S04 precipitate is always pigmented, and contains 

 considerable histidine. It is needless to say that histidine, as 



