J. L. Kr eider — Behavior of Typical Hydrous Bromides. 97 



Art. XIII. — The Behavior of Typical Hydrous Bromides 

 tchen Heated in an Atmosphere of Hydrogen Bromide; 

 by J. Lehn Kreider. 



[Contributions from the Kent Chemical Laboratory of Yale Univ. — cxxxvii.] 



In former papers from this laboratory* the results obtained 

 in the dehydration of certain hydrous chlorides in air and in 

 an atmosphere of hydrogen chloride have been studied and 

 compared. In the present paper the effects of treating typical 

 hydrous bromides in air and in an atmosphere of hydrogen 

 bromide are described. 



Hydrous barium bromide has been taken as a type of 

 hydrous salts which when heated in air lose their water with- 

 out much further decomposition ; hydrous magnesium bromide 

 as typical of salts which lose part of their water without much 

 further decomposition and the remainder with simultaneous 

 evolution of hydrogen bromide; and hydrous aluminum bro- 

 mide as typical of salts which lose their water only with simul- 

 taneous loss of hydrogen bromide. 



The method of experimentation was very similar to that 

 followed by Grooch and McClenahanf in their experiments 

 with hydrous chlorides. 



For these experiments two combustion tubes 30 cm in length 

 and 2 cm in diameter, set horizontally side by side in a tubulated 

 paraffin e bath, served as heating chambers. Each tube was 

 fitted with a thermometer. Portions of the hydrous bromides 

 to be treated were weighed into porcelain boats. One of 

 these boats was inserted in each tube about midway in the 

 bath (heated to a regulated temperature) and below the bulb 

 of- the thermometer, so that the temperature to. which the 

 material in the boat was submitted might be indicated by the 

 thermometer as accurately as possible. Through one tube 

 was drawn slowly a current of air purified by sulphuric acid, 

 and through the other was sent a slow current of purified 

 hydrogen bromide, generated in a flask by the action of bro- 

 mine on a heated solution of naphthalene and kerosene, and 

 passed through a purifying apparatus consisting of a tower 

 containing successive layers of red phosphorus and glass wool 

 and a wash bottle charged with a saturated solution of hydro- 

 bromic acid. At the end of a definite period, the boat was 

 withdrawn, placed in a desiccator for a suitable interval to 

 cool, and weighed. The residue in the boat was dissolved in 

 water, and the bromine was precipitated by silver nitrate, the 

 silver bromide being weighed on asbestos. In this way it was 



*Gooch and McClenahan, this Journal [4], xvii, 365. McClenahan, this 

 Journal [4], xviii, 104. f Loc. cit. 



Am. Jour. Sct. — Fourth Series, Vol. XX, No. 116.— August, 1905. 



7 



