186 



CHEMISTRY OF THE PROTEIDS 



CHAP. 



To more rapidly remove the peptones and other impurities from 

 the albumose precipitates, the latter should be rubbed for twenty 

 minutes each time with successive portions of saturated ammonium- 

 sulphate solution, at a temperature from 50-55, as at this temperature 

 the albumose is softer. 1 In the second table given above the albumoses 

 were rubbed fourteen times and precipitated six times before the 

 nitrogen in the filtrates became constant. Haslam also points out 

 that the greater the dilution of a mixture of albuminous substances 

 the smaller is the ' carrying-down ' power of the insoluble fraction ; 

 and the author has found similarly that the slower the salt-solution is 

 added in other words, the longer the time which is taken in causing 

 a precipitate, the less foreign bodies will be enclosed in any given 

 fraction. 2 The greater the difference in the constitution of two 

 albuminous substances the easier is it to separate them ; it is therefore 

 ' easy ' to separate albumins from albumoses, but difficult to separate 

 the various albumoses from one another. In every case the less 

 soluble albumins are kept in solution by the more soluble ones owing 

 to chemical interaction. 



So far Haslam has isolated from his primary albumoses, which are 



1 It was shown experimentally that albumoses may be heated to 60 with saturated 

 Na 2 S0 4 without undergoing decomposition. 



2 Slow addition of the salting-out medium may postpone the complete separation of 

 a fraction for days. The AUTHOR. 



