102 J. L. Kreider — Behavior of Typical Hydrous Bromides. 



When submitted at once, without preliminary heating, to a 

 temperature of 170° in air and 160° in hydrogen bromide, the 

 hydrous salt melts and in the melted condition loses water less 

 rapidly than the solid salt at a somewhat lower temperature. 

 This is what makes the break in the curves which indicate the 

 losses of water and hydrogen bromide. When the salt was 

 heated successively, for intervals of a half hour, at tempera- 

 tures varying by ten degrees, the progress of dehydration was 

 more uniform, as is shown in the accompanying diagram, all 

 the water being lost at 160° in air and 220° in hydrogen bro- 

 mide, the inhibiting action of hydrogen bromide upon the 

 dehydration being more marked as the temperature rises from 

 the point at which the first third is lost. 



Hydrous Aluminum Bromide. 



The hydrous aluminum bromide used was prepared by dis- 

 solving pure aluminum chloride in water, precipitated alumi- 

 num hydroxide by ammonium hydroxide, filtering off the 

 aluminum hydroxide, and washing until free from impurities. 

 This precipitate was then dissolved in hydrobromic acid, and 



