BACTERIAL CELLULAR SUBSTANCE 



89 



From this point Fischer's ester method for obtaining the 

 individual mono-amino-acids was carried out. 



This method is so well known that it is not necessary to 

 outline it here other than to say that after the amino-acids 

 have been produced by cleavage of the protein with concen- 

 trated acid, the hydrochloride of their ethyl esters is formed, 

 and later the free esters are separated by distillation in the 

 highest possible vacuum. These are then saponified and 

 the amino-acids crystallized and purified. 



The efficiency of this method depending in large measure 

 upon the vacuum secured, the yields here presented for 

 cleavage of the poisons might have been materially increased 

 with a better vacuum, the highest one possible with the 

 apparatus at hand varying from 20 to 30 mm. The following 

 table shows the results of the distillations of the free esters, 

 both the bath and vapor temperatures being given, the 

 amount of the distillates, and the yield of crude crystals 

 after saponification. 



DISTILLATION OF THE ESTERS OF THE MONO-AMINO-ACIDS FROM PROTEIN 



POISONS 



Tuberculosis Poison 



No distillate passed over between 20' 

 between 110 and 138. 



and 95, inside temperature, or 



