22 THE ATOMIC WEIGHTS. 



Hence we have 



H : O Ratio H-.H^O Ratio. 



15-878 17.877 



15.881 I7 .8 7 8 



15-878 17.873 



15.880 



15.877 17.881 



15-877 17-876 



15.877 17-875 



15-878 17.879 



15-879 17.881 



15-881 17.883 



15.881 17.883 

 15-882 17.878 



Mean, 15.8792, .00032 Mean, 17.8785, .00066 



Combined, these data give : 



From ratio H 2 : O . O 15.8792, .00032 



" H 2 :H 2 0^15.8785,^.00066 



General mean O 15.8790, =b .00028 



For details, Morley's fall 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 HC1 

 and NH 3 , and thence, using Stas' values for Cl and N, fixed by reference 

 to = 16, computed the ratio H : 0. 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,f who have discussed its sources of error. 



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

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

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

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

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

 the apparatus 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. 1894. 



fBer., 27, 2770. 



I Zeitsch. Anorg. Chem., :r, 14. 1895. 



