4 THE ATOMIC WEIGHTS. 



In the sum total of these nineteen experiments, 840.161 

 grammes of oxygen form 945.439 grammes of water. This 

 gives, in percentages, for the composition of water, oxygen 

 88.864; hydrogen, 11.136. Hence the atomic weight of 

 oxygen, calculated in mass, is 15.9608. In the following 

 column the values are given as deduced from the individual 

 data given under the headings F and G : 



15-994 

 16.014 

 16.024 

 15.992 

 15.916 

 15.916 



15-943 

 16.000 

 15.892 



15-995 

 15-984 



15-958 

 15.902 



15-987 

 15.926 

 15.992 

 15.904 

 15.900 

 16.015 



Mean, 15.9607, with a probable error of ± .0070. 



In calculating the above column several discrepancies 

 were noted, probably due to misprints in the original me- 

 moir. On comparing columns B and C with F, or D and E 

 with G, these anomalies chiefly appear. They were detected 

 and carefully considered in the course of my own calcula- 

 tions ; and, I believe, eliminated from the final result. 



The paper by Erdmann and Marchand* followed closely 

 after that of Dumas. The method of research was essen- 

 tially the same as that of the latter chemist, varying only 

 in points of comparatively unimportant detail. The results 

 are given in two series, in one of which the weighings were 



* Journ. f. Prakt. Chem., 1842, bd. 26, s. 461. 



