4 1 2 CHEMISTR Y OF THE DIGESTIVE PROCESSES. 
The amphopeptone is obtained from the filtrate after removal of the 
ammonium sulphate by complicated methods, consisting essentially in the 
removal of ammonium sulphate as far as possible by concentration ; solution 
of the amphopeptone in weak alcohol; removal of as much ammonium 
sulphate from the weak alcohol as possible by a freezing mixture ; removal of 
the alcohol by distillation ; removal of the last portions of ammonium sulphate 
by boiling with barium carbonate ; removal of the last traces of barium salts by 
cautious addition of dilute sulphuric acid; and finally, precipitation of the 
amphopeptone by excess of absolute alcohol. 
Neumeister's method for separating the < dim most* of peptic digestion. 
— The method of Kiilme and Chittenden for the separation of the 
various all minuses has been perfected by Xeumeister, 1 who has in 
addition proved that these bodies are not formed synchronously in the 
process of digestion, or other form of hydrolysis, but that there are two 
stages in the process. In the first stage proto- and heteroalhumoaes are 
formed, which are called for this reason primary albumoses ; in the second 
stage each of these primary albumoses gives rise to a deuteroalbumose, 
and these deuteroalbumoses are hence called secondary albumoses. 
Since heteroalbumose is completely and protoalbumose only partially 
precipitated by saturation with sodium chloride in neutral solution, 
while deuteroalbumose is not precipitated at all, it is easy, from a 
mixture of all three albumoses, to obtain a solution containing only 
heteroalbumose and protoalbumose; and on dialysis of this solution 
heteroalbumose, being insoluble in water, is precipitated alone, leaving 
in solution only pure protoalbumose. In this way pure proto- and 
heteroalbumoses can be obtained, but the preparation of pure deutero- 
albumose is not quite so easy. In the filtrate from saturation with 
sodium chloride there is not only deuteroalbumose but the unprecipitated 
residue of the protoalbumose, and on adding acetic acid this is thrown 
out along with the deuteroalbumose. However, a loophole is left in the 
fact that just as saturation in neutral solution does not precipitate all 
the protoalbumose, so saturation in acid solution does not precipitate all 
the deuteroalbumose. Xeumeister took advantage of this, sacrificed 
the first portion of deuteroalbumose thrown out by the acetic acid, 
accompanied by the last portions of protoalbumose, and then precipitated 
the fraction of deuteroalbumose left alone in solution by saturation with 
ammonium sulphate. 
Kiihne and Chittenden had already got round this difficulty of isolating 
deuteroalbumose by treating a dried mixture of the albumoses, such as is found 
in Witte's peptone, with neutral and saturated solution of sodium chloride. 
Here the deuteroalbumose only passes into solution. Although the proto- 
albumose would oid}' be partially thrown out of solution by saturating with 
sodium chloride, yet it has not the power when dry to pass into solution 
in such a solvent. "Witte's peptone is, however, a variable mixture, and 
Xeumeister, working with other samples, was unable to reobtain Kiihne and 
Chittenden's result ; it may be that they were working with a sample 
containing little or no protoalbumose. 
Xeumeister effects the separation as follows: — 
The faintly acid solution is saturated with ammonium sulphate, and so 
separated from peptones. The precipitate is dissolved by the addition of 
water, separated from the excess of the salt by dialysis, and then the neutral 
l Ztsckr. f. Biol., Miinehen, 18S7, Bd. xxiii. S. 3S1 : ibid., 1888, Bd. xxiv. S. 267 ; ibid., 
1890, Bd. xxvi. S. 324. 
