ATOMIC WEIGHTS 319 



wonder that Kessler felt satisfied of their general correctness, and of the 

 inaccuracy of the figures published by Schneider. Still, the old series 

 of data obtained by the titration of tartar emetic with dichromate con- 

 tained no evident errors, and was not accounted for. This series,^ if 

 we reduce all of Kessler's figures to a single common standard, gives a 

 ratio between K^Ct^O, and C4H^KSbO,4H20. 100 parts of the former 

 will oxidize of the latter: 



336.64 



338.01 



336.83 



337.93 



338.59 



335.79 



Mean, 337.30, ± .29 



From this Sb = 118.68. 



The newer atomic weights found in other chapters of this work will 

 be applied to the discussion of all these series further along. It may, 

 however, be properly noted at this point that the probable errors assigned 

 to the percentages of oxygen in three of Kessler's series are too low. 

 These percentages are calculated from the quantities of KCIO3 involved 

 in the several reactions, and their probable errors should be increased 

 with reference to the probable error of the molecular weight of that salt. 

 The necessary calculations would be more laborious than the importance 

 of the figures would warrant, and accordingly, in computing the final 

 general mean for antimony, Kessler's figures will receive somewhat higher 

 weight than they are legitimately entitled to. 



Naturally, the concordant results of Dexter, Kessler and Dumas led 

 to the general acceptance of the value of 122 for antimony as against the 

 lower figure, 120, of Schneider. Still, in 1871, linger ^ published the re- 

 sults of a single analysis of Schlippe's salt, NagSbS^.QHaO. This analysis 

 gave Sb=: 119.76, if S = 32 and Nai=23, but no great weight could be 

 attached to the determination. It served, nevertheless, to show that the 

 controversy over the atomic weight of antimony was not finally settled. 



More than ten years after the appearance of Kessler's second paper the 

 subject of the atomic weight of antimony was again taken up, this. time 

 by Professor Cooke. His results appeared in the autumn of 1877 * and 

 were conclusive in favor of the lower value, approximately 120. For full 

 details the original memoir must be consulted ; only a few of the leading 

 points can be cited here. 



1 Poggend. Annalen, 95, 217. 



^ Archiv der Pharmacie, 197, 194. Quoted by Cooke. 



* Proc. Amer. Acad., 5, 13. 



