•442 Thome — Barium Bromide by Hydrobromic Aoid. 



Considerable difficulty was had in drying the barium bro- 

 mide so as to obtain a constant weight, and the barium bromide 

 prepared in the manner described did not dissolve completely. 

 The results of these experiments are thereby lacking in uni- 

 formity. Presuming that the source of inaccuracy is to be looked 

 for in the formation of an oxybromide, the precipitate in the 

 next experiments, after filtering upon asbestos, was treated with 

 ammonium bromide and then dried over a radiator, — at first 

 at a low temperature and finally at a temperature high enough 

 to drive off the ammonium bromide. When the thermometer 

 inside of the radiator showed a temperature of 250° C. all the 

 ammonium bromide disappeared and left a barium bromide 

 which gave constant results, as shown in the following table. 







Table II. 





BaBr 2 taken. 



HBr and ethei 



BaBr-2 found. 



Error. 



grm. 



cm 3 . 



grm. 



grm. 



0-1330 



30 



0-1534 



+ 0-0004 



0-1013 



30 



0-1016 



+ 0-0003 



0-2769 



30 



0-2760 



— 0-0009 



0-2359 



30 



0-2353 



— 0-0006 



0-1580 



30 



0-1579 



—o-oooi 



0-2955 



30 



0-2947 



— 0-0008 



0*2822 



30 



0-2813 



— 0-0009 



0-1962 



30 



0-1962 



o-oooo 



0*4127 



30 



0-4125 



— 0-0002 



0-2751 



30 



0-2750 



—o-oooi 



0-3181 



30 



0-3183 



+ 0-0002 



0-3049 



30 



0-3039 



—o-ooio 



0-3754 



30 



0-3752 



— 0-0002 



These results indicate plainly that barium bromide, prepared 

 in a state of purity and free from oxybromide, may be com- 

 pletely precipitated from solution in water by treatment with 

 a mixture of hydrobromic acid and ether in equal parts and 

 saturation of the liquid with hydrogen bromide. 



Some experiments in which precipitation was effected by a 

 mixture of concentrated hydrobromic acid and ether in equal 

 parts, without saturating with the gas, led to similar results. 

 In these experiments the material weighed out was the crys- 

 tallized hydrous barium bromide, BaBr 2 . £H 2 0. 



Table III. 



BaBr 2 . 2H 2 



HBr + 



BaBr 2 



BaBr 2 





taken. 



ether 1:1. 



found. 



calculated. 



Error. 



grm. 



cm 3 . 



grm. 



grm. 



grm. 



0*2008 



30 CC. 



0-1793 



0-1790 



+ 0-0003 



0-2041 



30 



0-1822 



0-1820 



+ 0-0002 



0-2047 



30 



0-1821 



0-1825 



— 00004 



0-2171 



30 



0-1937 



0-1936 



+ 0-0001 



0-3101 



30 



0-2768 



0-2765 



+ 0-0003 



0-5035 



30 



0-4496 



04490 



+ 0-0006 



0-5015 



30 



0-4476 



0-4473 



+ 0-0003 



