196 



SMITHSONIAN MISCELLANEOUS COLLECTIONS 



VOL. 54 



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

 give in a third column the BaBr^ equivalent to 100 parts of AgBr: 



.0015 



Hence Ba = 137.380. From the two bromide ratios combined, Ag: 

 Br:: 100: 74.070. 



The last ratio Avas also determined by Thorpe/ incidentally to his 

 work on the atomic weight' of radium : 



Mean, 79.133, ± .0134 



Hence Ba = 137.384, in confirmation of Eichards' series. On combi- 

 nation with the latter no noteworthy change is produced. 

 The ratios for barium are now as follows : 



(1). 2Ag:BaCl2: : 100: 96.4947, ± .00086 

 (2). 2AgCl:BaCl2: :100:72.650, ± .0014 

 (3). 2Ag:BaCL.2H,0: : 100: 113.110, ± .0079 

 (4). BaS04:BaN,0«:: 100: 112.028, ±.014 

 (5). BaCL:BaS04: : 100: 112.075, ± .0016 

 (6). 2 Ag:BaBr„:: 100: 137.745, ±.0015 

 (7). 2AgBr:BaBr„: : 100: 79.132, ± .0015 



' Proc. Roy. Soc, 80A, 298. 1908. 



