22 



THE ATOMIC WEIGHTS. 



Hence we have- 



H-.H^O Ratio. 



17.877 

 17.S7S 



17.873 



17.8S1 

 17.876 

 17-875 

 17.879 

 17.881 

 17.883 

 17.883 

 17.878 



Mean, 17.8785, ±.00066 



Combined, these data give : 



From ratio H2 : O . O ^ 15.8792, zh .00032 



" U.^:Uf) O^ 15.8785, ±.00066 



General mean O -= 15.8790, ± .00028 



For details, IMorley's full paper must be consulted. No abstract can 

 do justice to the remarkable work therein recorded. 



Two other series of determinations, by Julius Thomsen, remain to be 

 noticed. In the earlier paper * he determined the ratio between HCI 

 and NH3, and thence, using Stas' values for CI and N, fixed by reference 

 to = 16, computed the ratio H : O. This method was so indirect as to 

 be of little importance, and gave for the atomic weight of oxygen approxi- 

 mately the round number 16. I shall use the data farther on in cal- 

 culating the atomic weight of nitrogen. The paper has been sufficiently 

 criticised by Meyer and Seubert,t who have discussed its sources of error. 



In Thomsen's later paper % a method of determination is described 

 which is, nice the preceding, quite novel, but more direct. First, alu- 

 minum, in weighed quantities, was dissolved in caustic potash solution. 

 In one set of experimeuts the apparatus was so constructed that the 

 hydrogen evolved was dried and then expelled. The loss of Aveight of 

 the ajjparatus gave the weight of the hydrogen so liberated. In the 

 second set of experiments the hydrogen passed into a combustion 

 chamber in which it was burned with oxygen, the water being retained. 

 The increase in weight of this apparatus gave the weight of oxygen so 

 taken up. The two series, reduced to the standard of a unit weight of 

 aluminum, gave the ratio between oxygen and hydrogen. 



*Zeitsch. Physikal. Chem., 13, 398. 



t Ben, 27, 2770. 



JZeitsch. Aiiorg. Chem., :i, 14. iS 



1894. 



