124 THE ATOMIC WEIGHTS. 



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

 drying 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, the measure- 

 ments of this ratio combine thus : 



Berzelius 112.175, =t .0071 



Struve ii 2.094, =t .7 r 



Marignac... 112.011,^.0071 



Richards 1 12.073, .0017 



General mean 112.075, .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 upon 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 2 equivalent 

 to 100 parts of silver stated : 



BaBr T Ag. Ratio. 



2.28760 1.66074 137.746 



3.47120 2.52019 I37-73 6 



2.19940 1.59687 I37.73 2 



2 -3597i i.7'3 2 3 '37-735 



2.94207 2.13584 137-748 



1.61191 1.17020 137.747 



2.10633 i.5 2 92i 137.740 



2.19682 2.11740 137.755 



237290 1.72276 137.738 



1.84822 L34I75 137.747 



5.66647 4.11360 I37.75 



3.52670 2.56010 37.756 



4-3 l6 90 3- I 343 I37-73 1 



3-36635 2.44385 137.748 



3.46347 2.51415 137-759 



Mean, 137.745, .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 BaBr 2 equivalent to 100 parts of AgBr : 



Proc. Amer. Acad., 28. 1893. 



