THE STORY OF NINETEENTH -CENTURY SCIENCE 



Subsequently Stas, the pupil of Dumas, undertook a 

 long series of determinations of atomic weights, with 

 the expectation of confirming the Proutian hypothesis. 

 But his results seemed to disprove the hypothesis, for 

 the atomic weights of many elements differed from 

 whole numbers by more, it was thought, than the limits 

 of error of the experiments. It is noteworthy, however, 

 that the confidence of Dumas was not shaken, though 

 he was led to modify the hypothesis, and, in accordance 

 with previous suggestions of Clark and of Marignac, to 

 recognize as the primordial element, not hydrogen it- 

 self, but an atom half the weight, or even one-fourth 

 the weight, of that of hydrogen, of which primordial 

 atom the hydrogen atom itself is compounded. But 

 even in this modified form the hypothesis found great 

 opposition from experimental observers. 



In 1864:, however, a novel relation between the 

 weights of the elements and their other characteristics 

 was called to the attention of chemists by Professor 

 John A. R. Newlands, of London, who had noticed that 

 if the elements are arranged serially in the numerical 

 order of their atomic weights, there is a curious recur- 

 rence of similar properties at intervals of eight elements. 

 This so-called "law of octaves" attracted little immedi- 

 ate attention, but the facts it connotes soon came under 

 the observation of other chemists, notably of Professors 

 Gustav Hinrichs in America, Dmitri Mendeleeff in Rus- 

 sia, and Lothar Meyer in Germany. Mendeleeff gave 

 the discovery fullest expression, expositing it in 1869, 

 under the title of " periodic law." 



Though this early exposition of what has since been 

 admitted to be a most important discovery was very 

 fully outlined, the generality of chemists gave it little 



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