98 J. L. Kr eider — Behavior of Typical Hydrous Bromides. 



possible to determine the loss of water and hydrogen bromide 

 from separate portions of the salt under examination, during 

 definite intervals and at fixed temperatures, both in an atmos- 

 phere of hydrogen bromide and in air, and to find for each 

 portion under examination what proportion of the total loss 

 was hydrogen bromide and what was water. The tabular 

 statements and the diagrams show the course of decomposition 

 of the various salts for the temperatures indicated. 



Hydrous Barium Bromide. 

 For the experiments with hydrous barium bromide, a well 

 crystallized specimen was prepared by taking commercially 

 pure barium carbonate, dissolving it in hydrochloric acid, 

 precipitating by ammonium carbonate, washing the precipitate, 

 dissolving in hydrobromic acid, and crystallizing and drying 

 the crystals by pressing between filter papers. The analysis 

 of different portions of this salt showed a definite composi- 

 tion, corresponding very closely to theory. 



Found. Theory. 



Ba 41-69$ 41 



Br... 48-05 47-95 



2H„0 10-26 10-45 



100-00^ 100-00$ 



The progress of the decomposition of this salt in air and in 

 hydrogen bromide when submitted for a half hour to the tem- 

 peratures indicated is shown in the accompanying table and 

 diagram. 



Here may be noted a gradual loss of water from 70° C. to 

 160° C. 5 at which point the water is entirely expelled, without 

 an appreciable loss of hydrogen bromide, either in air or 

 hydrogen bromide, and that hydrogen bromide influences the 

 process of dehydration in no marked way. There is nothing 

 to show that any part of the water sustains a peculiar relation 

 to the salt. 



Hydrous Magnesium Bromide. 

 Similar experiments were performed with hydrous magne- 

 sium bromide, prepared by dissolving magnesium ribbon in 

 hydrobromic acid and crystallizing the salt over sulphuric acid. 

 The analysis of the salt gave a definite constitution correspond- 

 ing fairly to theory. 



Found. Theory. 



Mg :... 08-68 08.27 



Br 54-61 54-69 



6HO 36-71 37-04 



100-00 100-00 



