188 THE ATOMIC WEIGHTS. 



Other defective series are given to iUustrate the partial 

 oxidation of the AsoOg by action of air. The foregoing 

 figures give us two distinct values for the molecular weight 

 of As^Og. In calculating from the bichromate results the 

 value for chromium deduced from Siewert's determinations 

 will be used, viz., Cr = 52.009, ± .025. 



From KCIO3 series ^'^^2*-*3 ^= l97-996> ± -049 



" K.,Cr,07 " " = 197.777, zfc .051 



General mean " = 197.894, dz .035 



Hence As = 75.002, ± .018. 



The general mean for As comes out as follows : 



From ASCI3 As = 74.829, dz .048 



" AsBrg " =74.046,^.058 



" As.^Og " = 75.002, zh .018 



General mean " = 74.918, dz .016 



If = 16, then As becomes = 75.090. 



ANTIMONY. 



After some earlier, unsatisfactory determinations, Ber- 

 zelius,* in 1826, published his final estimation of the atomic 

 weight of antimony. He oxidized the metal by means of 

 nitric acid, and found that 100 parts of antimony gave 

 124.8 of Sb^O,. Hence, if = 16, Sb = 129.03^ The 



* Poggend. Annal., 8, i 



