ATOMIC WEIGHTS 



27 



Taken as one series, the two sets of values, eight determinations in all, 

 give for the ratio H:0 the number 15.8799, ±.0046. This figure is 

 slightly higher than Morley's average, but below his maximum. 



Late in 1907, an elaborate investigation by Noyes^ was published, 

 covering five series of syntheses. The first series of twenty experiments, 

 however, was found to be affected by a small constant error, and it was 

 therefore rejected. The other series gave the subjoined results, with all 

 corrections, including the reduction to a vacuum, applied. 



Second Series. Electrolytic hydrogen, from sulphuric acid, was 

 weighed in palladium, and again in the copper oxide tube in which it 

 was oxidized to water. The apparatus was similar to that used in his 

 former research, and so, too, but with differences in detail, was the 

 procedure. 



Third Series. Hydrogen from sulphuric acid was passed directly into 

 the copper oxide bulb and there converted into water. 



Fourth Series. Hydrogen and oxygen, both obtained by electrolysis of 

 sulphuric acid, were directly combined by means of palladium, somewhat 

 as in Keiser's determinations. The use of copper oxide was thus avoided. 



^ Amer. Chem. Journ., 29, 1718. 1907. In Vol. 30, p. 4, 1908, Noyes discusses all determina- 

 tions of the atomic weight of hydrogen, and proposes criteria for the rejection of doubtful data. 



