376 ATROPIC ACID. 



crystallizes in long, lustrous, four-sided needles, which 

 are but slightly soluble in cold water, more easily 

 in boiling water, in alcohol in all proportions ; fusing 

 point, 130-131; distil almost entirely without de 

 composition. $-Bromcinnamic add crystallizes from 

 boiling water in large, hexagonal, flat crystals, which 

 are easily soluble in boiling water and in alcohol; fuse 

 at 120; and are converted in a-bromcinnamic acid 

 when subjected to distillation. 



The following acids are isomeric with cinnamic 

 acid : 



Atropic and Isatropic acids, C 9 H 8 2 . Both acids 

 are produced from tropic acid (p. 354) when this is 

 heated with baryta or concentrated hydrochloric acid ; 

 and are hence formed, together with tropic acid, in the 

 decomposition of atropin. Atropic acid is particularly 

 formed when baryta is employed ; isatropic acid, on 

 the other hand, when hydrochloric acid is the decom 

 posing agent. Atropic acid crystallizes in monoclinic 

 plates, dissolves in 700-800 parts water of the ordinary 

 temperature, easily in boiling water ; fuses at 106.5 ; 

 yields benzoic acid when oxidized with chromic acid ; 

 alphatoluic acid (p. 340) when melted with potassium 

 hydroxide; and hydratropie acid (p. 342) when treated 

 with nascent hydrogen. Isatropic acid forms thin, 

 rhombic laminae; is almost insoluble in cold water, but 

 very slightly in boiling water; and also in alcohol it is 

 less soluble than atropic acid. It melts at 200, is not 

 acted upon by chromic acid, and does not combine 

 with hydrogen. 



Phenylangelic acid, C n H 12 2 = C 6 H 5 .C 4 H 6 .CO.OH. 

 Is formed, like cinnamic acid, by heating oil of bitter 

 almonds with butyryl chloride at 120-130. Long, 

 fine, colorless needles ; fusing point, 81 ; difficultly 



