CHROMIUM. 249 



From (4) Ag^Crp^ =429.177, zb .2109 



From (10) CrClg = 157.266, ± .0113 



From (18) Am./Jr^O^ = 250.341, i .0164 



For the molecular weights of K^Cr^O. and BaCrO^ there are two esti- 

 mates each, as given below : 



From (11) K./'r^O^ = 292.433, ± .0189 



From (17) " =T 292.143, d= .0224 



General mean KjCr^O- = 292.31 1, ± .0144 



From (8) BaCrO^ = 252.549, =fc .0966 



From (9) " = 253.054, it .0377 



General mean BaCrO^ ^= 252.985, ±: .035 r 



Finall}', from these molecular weights, eight independent values are 

 obtained for the atomic weight of chromium : 



From Cr^g Cr = 5 1 . 796, ± .0039 



From AgjCrO^ " = 51.698, ± .0191 



From Ag^CrO^, 4NH3 " =51.175, ±.I74I 



From Ag2Cr207 "=51.904,^.1055 



From Am^CrjO, " = 51.659, zh .0085 



From KjCfjO, "=51.762,1^.0102 



From CrClg. . .♦ " = 51-729, ± .0183 



From BaCrO^ " = 53.077, zh .0362 



General mean Cr = 51.778, ± .0032 



If = 16, Cr = 52.172. 



Rejecting the last of the eight values, that from barium chromate, the 

 mean becomes — 



Cr ^ 51.767, ztz .0032. 



Even this result is probably too high, for it includes ratios which are 

 certainly erroneous, and which 3'et exert appreciable weight. From the 

 ratios which are reasonably concordant a better mean is derivable, as 

 follows : 



From ( I ) Cr = 5 1 . 741 , zh .0065 



From (2) " ^ 51.734, zh .0818 



From (14) " = 51.776, zh .0055 



From (3) and (15) " ^ 51.698, zh .0191 



From (4) " =51.904, dz .1055 



From (10) " = 51.729, zh .0183 



From (18) " = 51.659, zh .0085 



From (11) and (17) " =^ 51.762, zh .0102 



General mean Cr ^ 51.742, zh .0034 



If = 16, this Ijecomes 52.136, a value which is i)robably not very 

 far from the truth. 



