62 Society for Experimental Biology and Medicine. 



the free amino acids and the carbonates, instead of the sulphates, 

 as previously. Future experiments must determine which. A 

 control, a fraction of the original solution without the ferment, 

 has not changed during the time of the experiment. The 

 glycerol extract used, some of which was preserved, is still active ; 

 the ferment is therefore very long lived. A culture made of the 

 experimental material at the close of the experiment was negative. 



43 (186) 



A method for separating leucin from amino-valerianic acid. 



By P. A. LEVENE. 



[From the Rockefeller Institute for Medical Research^ 

 Separation of leucin from amino-valerianic acid was accom- 

 plished by means of lead acetate and ammonia. A basic lead salt 

 of leucin, insoluble in hot water, was formed. From a mixture 

 containing 52.53 per cent, of C and 9.39 per cent, of H, by the 

 use of these reagents, a substance was obtained, which had 54.55 

 per cent, of C and 9.90 per cent, of H. On reprecipitation it 

 acquired the composition : C = 54-70 per cent. ; H = 10.09 P er 

 cent. Leucin contains 54.89 per cent, of C and 10.01 per cent, 

 of H. 



