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



Boil for 5 minutes and filter. Concentrate the filtrate in an evaporat- 

 ing basin on a boiling water bath, and set the dish aside. Fine blue 

 needles of the copper salt are formed, having the composition 



CH 2 .CH.NH 2 .COO^ 

 CH 2 .CH.NH 2 .COO- 



NOTE. The copper hydroxide is prepared by adding 10 cc. of 20 per cent, 

 copper sulphate to about loocc. of distilled water, and stirring in i6cc. of 

 N. sodium hydroxide, previously diluted with about 300 cc. of water. The 

 precipitate is filtered and very thoroughly washed with cold distilled water 

 until neutral to litmus. 



80. Glutaminic Acid. 



A. Preparation of Glutaminic acid hydrochloride. 



(i.) To 100 grams, of gluten flour* in a 500 cc. round bottomed 

 flask add 300 cc. of pure concentrated hydrochloric acid, 

 and heat on the water bath until the gluten has dissolved. 



(ii.) Add 20 grams, of good decolourising charcoal, to remove the 

 dark " humin substance " that is formed during the 

 subsequent hydrolysis. 



(iii.) Boil on a sand bath under a reflux condenser for 6 hours, 

 (iv.) Dilute with an equal volume of water and filter. 



(v.) Evaporate the filtrate in vacuo to about 150 cc. (see pages 

 73 and 94). 



(vi.) Transfer the residue to a 300 cc. Erlenmeyer flask, cool 

 thoroughly, and saturate with dry hydrochloric acid 

 gas (see fig. 10). 



(vii.) Allow the flask to stand in the ice chest. After 24 to 48 

 hours a mass of crystals of glutammic acid hydrochloride 

 separates. Add an equal volume of ice cold alcohol. 



(viii.) Filter on a Buchner funnel through a piece of well washed 

 linen (handkerchief) cut to fit the funnel. Drain the 

 mother liquor away as completely as possible. 



(ix.) Wash the crystals with small amounts of ice cold concen- 

 trated hydrochloric acid. 



Yield : about 40 grams. 



* This can be obtained from Messrs. Bishop and Brooke, 21, Cock Lane, 

 Snow Hill, London, E.G. 



