ATOMIC WEIGHTS 



105 



A series was also begun in which one i^ample of potassium chloride 

 was to be balanced against silver from various sources, but only one 

 result is given, namely, 69.1240. This, with the previous series, gives a 

 mean of 69. 1230, ±.0002. 



The difference between the highest and the lowest of Stas' series cor- 

 responds to a difference of 0.021 in the atomic weight of potassium. The 

 rejection of the earlier work might be quite justifiable, but would exert 

 a very slight influence upon our final result. 



In 1903, incidentally to their work on cesium, Bichards and Archibald ' 

 published two analyses of potassium chloride, in which both ratios were 

 determined. That is, the silver chloride was weighed, giving data for 

 the second ratio, AgCl : KCl : : 100 : x. The results, with vacuum weights, 

 follow : 



In 1904 Archibald ' gave an additional series of determinations of these 

 ratios, also with vacuum weights, as follows: 



The measurements of these ratios by Richards and Staehler ■" are prob- 

 ably the most conclusive, for every care was taken to detect and avoid 

 constant errors, such as the authors believe were present, despite all 

 precautions, in the work of Stas. The occlusion of silver nitrate by silver 

 chloride is an error of this kind. The figures for the silver ratio are as 

 follows, with vacuum weights : 



iProc. Amer. Acad., 38, 456. 1903. 



- Trans. Roy. Soc. Canada, 1904, Section lU, p. 47. 



^ Publ. Carnegie Inst., Washington, No. 69, p. 7. 19C7. An advance publication in Ber. Dcutsch. 

 chem. Ges., 39, 3611, contained also the figures of some preliminary experiments, which the 

 authors discard in their final report. 



