NOTES ON ATOMIC WEIGHTS. 205 



certain temperature the gases do come off in atomic propor- 

 tions. In each experiment the weight of the gases given 

 off was about 23 grams. 



The weight of a litre of the gas thus given off from 

 solution of soda made from clean sodium was — 



°'5355 1Q ± o-ooooio, 

 and corresponds to a mixture of one volume of oxygen with 

 2*00357 volumes of hydrogen, but the excess of hydrogen 

 was found to be - ooo88 giving therefore the ratio in which 

 the gases combine as 1 : 2*00269. 



Part IV. gives an account of experiments in which 

 hydrogen was weighed in palladium foil, oxygen was 

 weighed in a globe, these were then made to combine, and 

 the water produced was weighed also. 



From these experiments we get the following values for 

 the atomic weight of oxygen : — 



(1) From the ratio of hydrogen and oxygen, - - 15-8792 



(2) From the ratio of hydrogen and water, - - - 15-8785 



or as a mean, ------ 15879 



From Parts I., II., III. of the memoir we get 



1*42000 2 



— 1 7 ~ x = 15-879 



•089873 2-00269 



How excellent Morley's work is can perhaps best be 

 seen by comparing his results with the means of those of 

 previous experimenters, 



Rayleigh's 



summary. Morley. 



Density of oxygen at Paris, - - 1-42961 1-42945 



Density of hydrogen at Paris, - - -08991 -089901 



Ratio of densities mean of all previous determinations, - - 15-9005 

 Ratio of densities, Morley's, 15-9002 



Ratio of combining volumes, Morley, - 2*00269 

 „ ,, Scott, - 2*00285 



,, ,, Leduc, - 2*0037 (corrected = 2 0024) 



Although the results obtained by Thomsen agree 

 wonderfully well with those of Morley it is not because his 

 apparatus and his methods of working are so carefully 

 elaborated. On the contrary what strikes one most forcibly 

 is the extreme simplicity of the apparatus and mode of 



