92 PROPERTIES OF CERTAIN AMINO-ACIDS. [CH. IV. 



G. Crystallisation. 



(i.) Evaporate in vacuo (fig. 8) at a temperature of about 45 C. 

 until the volume is reduced to rather less than iocc., 

 best ascertained by measuring 10 cc. into the flask before 

 the evaporation is commenced. (See page 99.) 



(ii.) Disconnect the apparatus with the usual precautions. 

 (See page 74.) 



(iii.) Heat for a short time on a boiling water bath, shaking the 

 fluid round the flask to get as much as possible into 

 solution. 



(iv.) Transfer to a small crystallising dish or beaker and add 

 an equal volume of strong alcohol. 



(v.) Allow the dish to stand in a cool place over-night, 

 (vi.) Filter off the precipitate, using a suction pump. 



(vii.) Wash out the flask and dish with small amounts of 

 alcohol of increasing strengths, 65, 75, 85, and 95 per 

 cent., using these for washing the crystals on the filter. 



(viii.) Dry the crystals in the air. 



H. Concentration of the mother liquors. 



(i.) Evaporate the mixed mother liquors and alcoholic washings 

 in a boiling water bath, adding strong alcohol from time 

 to time, until the crystalline precipitate that forms at the 

 edge does not redissolve in the body of the fluid when 

 stirred. 



(ii.) Set the dish aside for at least an hour. 



(iii.) Filter off the crystals and wash with small amounts of 

 * alcohol of gradually increasing strength. 



(iv.) Dry in the air. 

 Yield: 0-6 to 2 grams. 



