OP ARTS AND SCIENCES. 201 



Finally, we attempted to separate the two acids by fractional satura- 

 tion. Although the products thus obtained gave us analytical results 

 that were far from satisfactory, we found that the separation could be 

 effected with tolerable precision, the brompropiolic acid being the 

 stronger acid, and that this was the most convenient way of preparing 

 material sufficiently pure for further work, in any considerable quan- 

 tity. Pure substance melting at 104-105° was dissolved in water, 

 and a little less than the calculated amount of baric carbonate was 

 added. The clear solution was then freed as completely as possible 

 from dibromacrylic acid by repeated extraction with ether, and the 

 baric brompropiolate obtained by spontaneous evaporation. 



Our analytical results show that the material analyzed was not 

 pure, and yet they leave no doubt as to its nature. 



I. 0.6974 grm. of substance, dried over HgSO^, gave 0.3968 grra. 



CO2 and 0.0347 grm. H,0. 

 II. 0.3060 grm. of substance, dried over H^SO^, gave 0.1657 grm. 

 BaSO,. 



III. 0.1829 grm. of substance, dried over HgSO^, gave 0.0973 grm. 



BaSO,. 



IV. 0.4325 grm. of substance, dried over H^SO^, gave 0.2305 grm. 



BaSO^. 



Calculated for Ba(CsBr02)2. Found. 



I. II. ni. IV. 



C 16.63 15.52 



H — 0.55 



Ba 31.63 31.84 31.27 31.32 



"We have been unable to make any satisfactory determinations of 

 the water of crystallization, since the salt cannot be heated, and even 

 on standing over sulphuric acid in the cold it is slowly decomposed. 

 The salt when crystallized from water probably contains four mole- 

 cules of water. 



I. 2.1104 grm. of the air-dried salt lost over sulphuric acid 0.2803 



grm. 

 II. 0.9828 grm. of air-dried substance lost over HgSO^ 0.1316 grm. 



Calculated for Ba(C3Br02)2.4H20 Found, 



I. II. 



HjO 1426 13.28 13.39 



