Thome — Barium Bromide by Hydrobromic Acid. 441 



Art. XLYI. — The Precipitation of Barium Bromide by 

 Hydrobromic Acid / by Norman C. Thorne. 



[Contributions from the Kent Chemical Laboratory of Yale University — 



CXXXI.] 



In former articles from this laboratory,* processes for the 

 separation and determination of certain chlorides, hydrous or 

 anhydrous, by the action of hydrochloric acid have been 

 studied. The present article deals with the similar separation 

 and determination of barium bromide by the agency of hydro- 

 bromic acid. 



The hydrobromic acid used in the experiments to be 

 described was prepared by dropping from a stoppered funnel 

 liquid bromine into naphthalene dissolved in kerosene, passing 

 the hydrogen bromide evolved through a purifying tower 

 charged in layers with glass-wool and red phosphorus and a 

 water trap, and saturating distilled water with the gas thus 

 •purified. 



Pure barium bromide was made by dissolving barium chlo- 

 ride in water, precipitating barium carbonate by ammonium 

 carbonate and ammonium hydroxide, washing the precipitate 

 by decantation and dissolving it in hydrobromic acid. This 

 solution of barium bromide was evaporated to dryness and the 

 barium bromide thus obtained was used in the following 

 experiments. 



In the first series of experiments a weighed amount of the 

 barium bromide was dissolved in the least volume of water, 

 and treated with hydrobromic acid or with a mixture of hydro- 

 bromic acid and ether in equal volumes. The liquid was sat- 

 urated with hydrobromic acid gas and filtered upon asbestos, 

 and the precipitate washed by a mixture of hydrobromic acid 

 and ether, dried in air bath or over Bunsen flame and weighed 

 as BaBr 2 . The details of these experiments are given in 

 Table I. 







Table I. 







Br 2 taken. 



HBr. 



HBr and ether. 



BaBr.j fonnd. 



Error. 



grm. 



cm 3 . 



cm 3 . 



grm. 



grm. 



0-2932 



30 





0-2934 



+ 0-0002 



0-1264 



30 





0-1260 



— 0-0004 



0-1134 



30 





0-1132 



— 0-0002 



0-1347 





30 



0-1367 



+ 0-0020 



0-1040 





30 



0-1035 



— 0-0005 



0-0744 





20 



0-0748 



+ 0-0004 



0-1197 





30 



0-1211 



+ 0-0014 



0-4327 



30 





0-4345 



+ 0-0018 



* This Journal (3), xliii, 521 (Mar) ; (4), ii, 416 (Gooch and Havens); (4), 

 iv, III (Havens); (4), vi, 45 (Havens); (4), vi, 396 (Havens). 



