376 PROCEEDINGS OF THE AMERICAN ACADEMY. 



The second sample of strontic bromide was prepared from similarly 

 treated strontic nitrate which had been recrjstallized four times in- 

 stead of twice. The nitrate was converted into oxide by ignition in a 

 nickel crucible ; and the dissolved residue was filtered to get rid of a 

 small amount of nickel. Ammonic sulphydrate gave no trace of color- 

 ation to a portion of the filtrate. Two recrystallizations in a platinum 

 bottle sufficed to free the strontic hydrate from a trace of undecora- 

 posed oxides of nitrogen, and the last crystals dissolved to form an 

 absolutely clear solution in pure hydrobroraic acid.* The solution of 

 strontic bromide was evaporated to crystallization, the crystals were 

 dehydrated, and the anhydrous salt was fused; finally, after solution, 

 standing, and filtration, a fresh crop of crystals was obtained. This 

 sample, labelled No. II., was used for Analysis 14. 



Among several different methods for obtaining pure strontic salts, 

 that recommended by Barthe and Falieres j seemed to promise well 

 and accordingly the third preparation was based upon their work 

 The so called " pure " strontic chloride of commerce was dissolved in 

 water, treated with ammonic hydrate and a little carbonate, and filtered 

 from the precijjitate containing iron, aluminum, and so forth. To 

 the filtrate was added an excess of sulphuric acid, and the precipitated 

 strontic sulphate was thoroughly washed with dilute sulphuric acid and 

 then with pure water, in the hope of freeing it from magnesium and 

 calcium. When the wash water became neutral to methyl orange the 

 precipitate was treated with enough ammonic carbonate solution to 

 convert about half of it into carbonate, and the mixed precipitate was 

 then washed with water by decantation until only a very small con- 

 stant trace of sulphuri;' acid (due to strontic sulphate) was found in 

 the decantate. The carbonate was then decomposed by pure hydro- 

 chloric acid, and the solution was allowed to stand in a glass flask for 

 nine months over the undecomposed sulphate, with occasional shaking. 

 The strontic chloride was decanted, the sulphate was washed once 

 with water, and the filtered decanted liquid was evaporated in a plati- 

 num dish until most of the free hydrochloric acid had been expelled. 

 The dissolved residue was neutralized with ammonia, shaken with a 

 little ammonic carbonate, and then filtered. To the greatly diluted 

 filtrate was added an excess of pure ammonic carbonate, and the pre- 

 cipitate was washed until the wash water was free from chlorine. 

 The strontic carbonate was dissolved in nitric acid which had been 



* See these Proceedings, XXVIII. 17, bottom of page. 



t Journ. Chem. Soc, Abs. 1892, p. 1277. Bull. Soc. Chim., [3.], VII. 104 



