18-i SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 54 



Mean, 123,477 

 Mean of all as one series. 123.460, ± .0082 



Hence Sr = 87.37. 



From series B, by deducting Marignac's water determinations, 40.563 

 per cent, in mean, the ratio between silver and the anhydrous chloride 

 can be determined. The value found is 2Ag: SrCU :: 100 : 73.3907. ± 

 .00G5. This is so much lower than the measurements previously cited 

 that it needs no further consideration. 



Marignac also determined the ratio between strontium chloride and 

 strontium sulphate. By direct conversion, one hundred parts of the 

 former salt gave the quantities of sulphate shown in the third column 

 of the next table : 



5.942 srm. SrCL gave 6.887 SrS04. Ratio, 115.932 



5.941 " 6.8855 " " 115.949 



5.942 " 6.884 " " 115.927 



Mean, 115.936, ± .004 



Hence Sr- 86.90. 



Richards,' in his study of strontium bromide, followed pretty 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 determined. 

 First, the ratio 2Ag: SrBro : : 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. .\mer. Acad., 1894, 369. 



