STRONTIUM. 115 



In the same paper Marignac gives two sets of determinations of the 

 percentage of water in crystallized strontium chloride. The first set, cor- 

 responding to " B " ahove, is as follows : 



40.556 

 40.568 

 40.566 



Mean, 40.563 



In the second set ten grammes of salt were taken at a time, and the 

 following percentages were found : 



40.58 



40.59 

 40.58 



Mean, 40.5S3 

 Mean of all as one series, 40.573, zb .0033 



The chloride used in the series of estimations last given was subse- 

 quently employed for ascertaining the ratio between it and the sulphate. 

 Converted directly into sulphate, 100 parts of chloride yield the quanti- 

 ties given in the third column : 



5.942 grm. SrCL, gave 6.887 5^™- SrSO^. 115.932 



5.941 " 6.8855 " I '5-949 



5.942 " 6.884 " 115-927 



Mean, 1 15.936, ± .004 



Richards.* in his study of strontium bromide, followed ])retty much 

 the lines laid down in his work on barium. The properties of the 

 bromide itself were carefully investigated, and its purity established 

 beyond reasonable doubt, and then the two usual ratios were deter- 

 mined. First, the ratio Ag^ : SrBr,, : : 100 : x, by titration with standard 

 solutions of silver. For this ratio there are three series of measurements, 

 by varied processes, concerning which full details are given. The data 

 obtained, with weights reduced to a vacuum, are as follows : 



■ Proc. Amer. Acad, of Sciences, 1894, p. 369. 



