OF ARTS AND SCIENCES. 211 



examined. On boiling with an excess of baric hydrate, it is decom- 

 posed in essentially the same way as the dibromacrylic acid, baric 

 malonate being formed in abundance. This decomposition with alka- 

 lies we have not followed further, since it was evident that cblorpro- 

 piolic acid should be the intermediate product formed; and we wished 

 not to interfere with the researches which Wallach had already under- 

 taken with Bischof,* concerning the decomposition of /? dichloracrylic 

 acid by alkalies. 



Although the acid does not add bromine when heated with it to 

 100° in chloroform solution, it readily forms an addition product when 

 heated for some time with undiluted bromine at 100°. Tlie dichlordi- 

 brompropionic acid which is thus formed is at present under investi- 

 gation in this laboratory. 



Substituted Acrylic Acids from Brompropiolic Acid. 



Mr. C. F. Mabery has studied with me some of the substituted 

 acrylic acids which may readily be made by the addition of halogens 

 or haloid acids to brompropiolic acid. 



Dibromacrylic Acid of Fittig and Petri. 



Brompropiolic acid dissolves easily in concentrated hydrobromic 

 acid (b. pt. 126°), and on standing for a short time the solution deposits 

 abundant crystals of a dibromacrylic acid, which is identical with that 

 described by Fittig and Petri as resulting from the decomposition of 

 tribromsuccinic acid. This acid may also be prepared to advantage 

 from the solution of baric brompropiolate and baric bromide which is 

 obtained in the pre^jaration of baric dibromacrylate by the action of 

 baric hydrate upon mucobromic acid. It is only necessary to pre- 

 cipitate the barium with dilute sulphuric acid, and to concentrate the 

 solution upon the water bath. The acid which separates as the solu- 

 tion cools is easily purified by recrystallization. 



From a hot concentrated solution, the acid falls at first as an oil ; 

 but, after the solution has cooled somewhat, it separates in pearly 

 scales, which melt at 85-86°. In analysis they gave the required 

 percentage of bromine. 



0.2614 grm. of substance gave 0.4283 grm. AgBr. 



Calculated for C3H2Br202. Found. 



Br 69.57 69.72 



* Berichte der deutsch. chein. Gesellsch., xi. 751 ; xii. 57. 



