152 ASPARTIC. GLUTAMIC. 



in which solution it is gradually converted into the carbonate. 

 At ordinary pressures when heated to 60 it is decomposed into am- 

 monia and carbonic anhydride, but under pressure at 130 -140 

 it yields urea. When electrolysed in told aqueous solution by a 

 rapidly and continuously commutated current the salt similarly 

 loses water and yields urea (Drechsel). The dehydration may be 

 represented as taking place in the following way : 



+ H 2 0. 

 ii. 



or by the action first of H 2 and then of O. 1 



2. Aspartic (or asparaginic] acid. C 4 H 7 N0 4 . [COOH . CH 2 . CH 

 . COOH]. Amido-succinic acid. 



This acid is chiefly obtained from plant extracts, and occurs 

 notably in beet-sugar molasses. It may be synthetised, but is 

 most conveniently prepared by boiling asparagin with caustic 

 alkalis or mineral acids. It is also a typical product of the action 

 of boiling mineral acids and caustic baryta on both vegetable and 

 animal proteids (antea p. 49) and of acids on gelatin, 2 being 

 usually accompanied by its homologue, glutamic acid. It is also 

 now recognised as a product in minute quantities of the pancrea- 

 tic digestion of fibrin 3 and vegetable glutin, 4 although it does 

 not occur as a constituent of any animal tissue or secretion. It 

 crystallises in rhombic prisms which are but sparingly soluble in 

 cold water or alcohol, but readily soluble in boiling water. Its 

 solutions, if strongly acid, are dextrorotatory, but if alkaline, Isevo- 

 rotatory. It forms a characteristic readily cry stalli sable compound 

 with oxide of copper, which is practically insoluble in cold, but 

 soluble in boiling water, and may be used for the separation of 

 aspartic acid from solutions in which it is mixed with other 

 substances. 5 



3. Glutamic (or glutaminic) acid. C 5 H N0 4 . (Amido-pyro- 

 tartaric acid). 



This acid is homologous with aspartic acid. The circumstances 

 and conditions under which it occurs are in general the same as 

 for aspartic acid, but it has not as yet been obtained by the action 

 of pancreatic enzymes on proteids and is never found in any 

 animal tissues or secretions. But as a product, often to a large 

 amount, of the artificial decomposition of proteids it acquires some 



1 Cf. Ludwig's Festschrift, 1887, S. 1. 



2 Horbaczewski, Sitzb. d. k. Akad. d. Wiss. Wien. Bd. LXXX. (2 Abth.) Juni- 

 Hft. 1880. 



3 Radziejewski u. Salkowski, Ber. d. deutsch. chem. Gesell. Jahrg. vu. (1874), 

 S. 1050. 



* v. Knieriem, Zeitsch. f. Bid. Bd. xi. (1875), S. 198. 



5 Hofmeister, Sitzb. d. k. Akad. d. Wiss. Wien, Bd. LXXV. (1877), 2 Abth. 

 Marz-Hft. 



