352 



VOL. 54 



Mean, 88.334, d: .0009 



Hence Cr = 51.987. 



Similar determinations of the atomic weight of chromium were made 

 by Baxter and Jesse/ who analyzed silver dichromate. In a single experi- 

 ment 6.26657 grammes of AgoCr.O, gave 4.16076 of AgCl. Eatio, 

 150.611. Giving this the weight of a single determination in the fol- 

 lowing bromide series, ±.0024, it combines with the earlier measurements 

 by Berlin and Siewert to a general mean of 150. 612, ±.0024. The older 

 work vanishes. Hence Cr = 52.003. 



The dichromate-bromide series of determinations gave the subjoined 

 data: 



AgiCViO.,. AgBr. Ratio. 



5.71554 4.97149 114.966 



4.87301 4.23888 114.960 



7.45476 6.48425 114.967 



4.75269 4.13420 114.960 



8.15615 7.09495 114.957 



6.15412 5.35309 114.964 



6.83662 5.94768 114.963 



5.39883 4.69631 114.959 



Mean, 114.962, ± .0008 



Hence Cr = 51.995. 



The following ratios are now available for computing the atomic weight 

 of chromium : 



(1). Percentage CrA from AgjCrO^, 22.934, ± .0018 

 (2). Percentage CrA. from Ag.CrA, 35.236, ± .0335 

 (3). 2AgCl:Ag2Cr04: : 100: 115.731, ± .0023 

 (4). 2AgCl:Ag,CrA: : 100: 150.012, ± .0024 

 (5). 4AgCl:Cr,03: 100: 26.620, ± .0052 

 (6). Percentage Cr^Os in Cr„( 804)3, 38.838, ± .0087 

 (7). Percentage Cr^Oj in AmCr(S04),.12HA 16.143, ± .0125 

 (8). BaS04:BaCr04: : 100: 108.9815, ± .0369 

 (9). BaCrO,:BaCl„: : 100: 81.702, ± .014 

 (10). 3AgCl:CrCl3: : 100: 36.842, ± .0031 

 (11). 2KC103:K2CrA: :100:120.216, ± .0235 

 (12). Percentage Ct„0, in Ag,Cr04.4NH3, 19.059, ± .0074 

 (13). 2AgCl:Ag,Cr04.4NHs: : 100: 139.357, ± .1109 

 (14). Percentage CrA in AmzCr^Or, 60.337, ± .0029 



^ Journ. Amer. Chem. Soc, 31, 541. 1909. 



