40 HANDBOOK FOR BIO-CHEMICAL LABORATORY. 



rule, precipitated by metallic salts. The boiling hot solution 

 may, however, be precipitated by a boiling hot solution of 

 copper acetate. It forms crystalline compounds with sul- 

 phuric, hydrochloric, and nitric acids. 



Pure tyrosin crystallizes in colorless, silky, fine needles, 

 which are often grouped in tufts or rosettes. From very 

 impure solutions it separates in part or wholly in nodules and 

 balls very like leucin. It is soluble with difficulty in water, 

 being dissolved by 2454 parts water at 20C., and 154 parts 

 boiling water. It is insoluble in alcohol and ether. Tyrosin 

 is readily soluble in solutions of ammonia, caustic alkalies, and 

 alkaline carbonates. It is also soluble in dilute mineral acids, 

 with which it forms unstable compounds. 



Aspartic Acid, C 4 H,N0 4 . 

 AMIDO-SUCCIKIC ACID, C 2 H 3 (NH 3 )(CO.OH) 2 . 



Preparation. The mother-liquor from which leucin and 

 tyrosin have crystallized out (see page 38) is further concen- 

 trated and treated with a little alcohol, when, after some 

 time, new crystalline crusts will separate. These are dissolved 

 in water, and the solution boiled with freshly precipitated 

 cupric hydrate. On filtering the blue solution will deposit 

 the copper compound of aspartic acid, which occurs as light 

 blue needles. These are dissolved in HC1 anddecomposed by 

 H 2 S, when white crystalline plates of aspartic acid will sepa- 

 rate out. This is purified by crystallization from boiling water. 



Properties. Aspartic acid crystallizes in rhombic prisms 

 which are sparingly soluble in cold water or alcohol, but 

 readily soluble in boiling water. Its solution, strongly acid 

 with nitric acid, is dextro-rotatory, (a) D -\- 25.16, but in 

 alkaline solution it is laevo-rotatory. With copper it forms a 

 compound soluble in boiling water, but nearly insoluble in 

 cold water. 



