124 THE ATOMIC WEIGHTS, 



This mean is subject to a small correction due to loss of chlorine on 

 dryino; the chloride, which reduces it to 112.073. Omitting Turner's 

 single determination as unimportant, and assigning to the work of Ber- 

 zelius and of Struve equal weight with that of Marignac, tlie measure- 

 ments of this ratio combine thus : 



Berzelius 112.175, ± .007 1 



Struve II 2.094, rh .007 1 



Marignac 1 12.01 1, zh .0071 



Richards 1 12.073, ± -0617 



General mean 112.075, zt .0016 



In an earlier paper than the one previously cited, Richards* studied 

 with great care the ratios connecting barium bromide with silver and 

 silver bromide. The barium bromide was prepared by several distinct 

 processes, its behavior upon dehydration and even ui:)on fusion was 

 studied, and its specific gravity was determined. The ratio with silver 

 was measured by titration, a solution of hydrobromic acid being used 

 for titrating back. The data are subjoined, with the BaBr, equivalent 

 to 100 parts of silver stated : 



Mean, 137.745, =b .0015 



The silver bromide in most of these determinations, and in some others, 

 was collected and weighed in a Gooch crucible with all necessary pre- 

 cautions. Vacuum standards were used throughout for both ratios. I 

 give in a third column the BaBr2 equivalent to 100 i)arts of AgBr : 



§ Proc. Amer. Acad., 28. 1893. 



