OF ARTS AND SCIENCES. 279 



stances are not simply isomeric, but identical. This point, however, 

 cannot be positively settled till a careful study has been made of the 

 addition products of both compounds. 



a Monohromcinnamic Acid. 



The nearly clear liquid from which the bromstyrol had been dis- 

 tilled was made slightly alkaline with sodic carbonate, and shaken 

 with ether to remove the last traces of the oil. The solution was then 

 evaporated to a volume of about one hundred cubic centimeters and 

 acidified with dilute hydrochloric acid. A white precipitate was 

 thrown down, which after one crystallization from boiling water melted 

 at 132° C, and proved to be the a monohromcinnamic acid. 



Two bromine determinations gave the following results : — 



1. 0.1986 gr. substance gave 0.1661 gr. AgBr. 



2. 0.2242 gr. substance gave 0,1874 gr. AgBr. 



Calculated for CgHjBrOj. j Found. ^ 



Br 35.25 35.58 35.56 



The barium salt, formed by adding baric chloride to a dilute solution 

 of the acid in warm water, resembled in every respect the barium salt 

 of a monohromcinnamic acid as described by Glaser.* It was only 

 sliiihtlv soluble in cold water and insoluble in alcohol. The barium 

 salt of the ji bromcinnamic acid is hj'groscopic, and soluble in alcohol. 



The salt gave on analysis the following result : — 



0.3092 gr. substance gave 0.1233 gr. BaSO,. 



Calculated for (C9n6Br02)2Ba. Found. 



Ba 23.23 23.42 



The formation of the a monohromcinnamic acid from both the a 

 and P phenyltribrompropionic acids was rather to be expected, as 

 Glaser has found that the fB monohromcinnamic acid is changed into 

 the a by distillation, or by heating it with hydriodic acid,t and, more- 

 over, Barish has shown that from both the a and /3 acids only the 

 ethyl ether of the a acid can be obtained. t 



In speaking of these acids we have used the nomenclature proposed 

 by Glaser. For although it is very probable that his a acid is in fact 



* Annalen der Clieniie, cxliii. 334. t Ibid., 33G. 



X Jour, fur Prakt. Chemie, cxxviii. 185. 



