CH. IV.J 



LEUCINE. 



99 



Properties of leucine. Pure leucine is only very 

 slightly soluble in cold water, but when it is contaminated 

 with other amino-acids it is easily soluble. It is insoluble 

 in absolute alcohol, but is soluble in hot dilute alcohol, and 

 can be freed from tyrosine by crystallising from hot alcohol. 

 When pure it crystallises in pearly plates. When impure 

 it is apt to crystallise in soft spherical masses, which have a 

 slightly radiate structure. 



It melts at 297 with decomposition. When heated 

 gently in an open tube it sublimes at a temperature below 

 its melting point and emits a characteristic smell of amyl- 

 amine. It is laevorotatory in aqueous solution, but 

 dextrorotatory in solution in hydrochloric acid. 



D- 



Topump 



Fig. 13. Distillation in vacuo by use of a Claisen flask (A). Alcohol or more 

 of the fluid can be added through E as the distillation proceeds. D is a 

 tube drawn out to a fine capillary through which a small amount of air 

 enters the boiling fluid to prevent excessive bumping. 



