ATOMIC WEIGHTS 449 



that recently, to prove the opposite. For example, Parker and Sexton ' 

 assert that in fifteen electrolytic comparisons of silver and cobalt, they 

 have obtained a mean value of Co = 57.7, which is lower than the atomic 

 weight of nickel. Barkla and Sadler,'" in studying the permeability of 

 metals to the secondary Eontgen rays, have found that property to be a 

 periodic function of the atomic Aveights. By interpolation in the periodic 

 curve so obtained they find values for Ni ranging between 61.2 and G1.6, 

 whereas the currently accepted atomic weight appears to be anomalous, 

 at least as regards the physical property now under consideration. These 

 conclusions, however, cannot weigh very heavily as against the clear 

 chemical evidence. As for Parker and Sexton's work, the authors give 

 no details which would furnish an adequate basis for discussion. 



RUTHENIUM. 



The atomic weight of this metal has been determined by Claus and 

 by Joly. Although Claus ' employed several methods, we need only 

 consider his analyses of potassium rutheniochloride, KjEuClg. The salt 

 was dried by heating to 200° in chlorine gas, but even then retained a 

 trace of water. The percentage results of the analyses are as follows: 



Eeckoning directly from the percentages, we get the following dis- 

 cordant values for Eu : 



From percentage of metal Ru = 103.24 



From percentage of 2KC1 " = 107.41 



From percentage of 3C1 " = 97.09 



These results are obviously of little importance, especially since the 

 best of them is not in accord with the position of ruthenium in the 

 periodic system. The work of Joly is more satisfactory." Several com- 



1 Nature, 76, 316. 1907. 



2 Phil. Mag. (6), 14, 408. 1907. 

 sjourn. prakt. Chem., 34, 435. 1845. 

 ■* Compt. Rend. , 108, 946. 



