Manchester Memoirs, Vol. Iv. (191 1), No. 33. 



XXII. The Development of the Atomic Theory : 

 (7) The rival claims of William Higgins and 

 John Dalton. 



By Andrkw Norman Meldrum, D.Sc. 



(Communicated by Mr. R. L. Taylor, F.C.S., F.I.C.) 



Received March 22nd, igii. Read April 2jlli, igii. 



The rival claims of William Higgins and John Dalton 

 to the atomic theory were much discussed early in the 

 nineteenth century. The result of the discussion was, 

 on the whole, favourable to Higgins. But from a variety 

 of reasons, this result has been forgotten, and Dalton's 

 claims are supposed at the present time to be beyond 

 dispute. The author, in reviving the subject, hopes to 

 present the facts, and to offer considerations, so as to 

 enable anyone interested to come to a simple and fair 

 conclusion upon it. 



With the above purpose in view, it is necessary to 

 consider the question. What is the essence of Dalton's 

 atomic theory .' This question, one of much interest, has 

 proved in the experience of writers on the subject, one also 

 of much difficulty. An answer to it, which cannot be set 

 aside, has recently been given by Larmor. In his Wilde 

 Lecture — " On the Physical Aspects of the Atomic Theory " 

 — he has expressed the Daltonian principle in the words " a 

 definite molecule for each substance." He explains this 

 more fully as follows: — " Perhaps the new feature developed 

 by Dalton is at bottom describable as the principle of 



futie i2t/i, igii. 



