Meldrum, Developmoit of tJic Atomic Theory, 



Dalton himself. This is simply what was to be expected 

 in the nature of the case. Moreover, since Dalton was 

 inconsistent in the matter, no single account of his can be 

 accepted at its face value. The version of the origin 

 which is advanced in this paper, consequently, need not 

 be rejected off-hand, as not having received the sanction 

 of Dalton. It is offered as a fair account of the present 

 state of our knowledge, on a matter on which absolute 

 certainty is not yet attainable. 



The paper is divided into two parts : — I. The princi- 

 ples of Dalton's theory ; II. The genesis of the theory. 



I. The principles of Dalton's theory. 



Hie first table of atomic weights. 



For the present purpose of studying the origin of the 

 chemical theory, Dalton's note-books contain material of 

 inestimable value : they afford facts which cannot be 

 disputed. Under date 6th September, 1S03, there is an 

 atomic weight table of the highest interest. It is quoted 

 by Roscoe and Harden as follows : — * 



Ult. at. hydrogen ... ... i 



» » oxygen 566 



„ » azote 4 



„ „ carbon 4-5 



„ „ water ... ... 6 66 



„ „ ammonia ... ... 5 



„ „ nitrous gas... ... 966 



„ „ „ oxide ... 1366 



„ „ nitric acid ... ... 1 5'32 



„ „ sulphur ... ... 17 



„ „ sulphurous acid ... 2266 

 „ „ sulphuric „ ... 2832 

 „ „ carbonic „ ... 158 



,, „ oxide of carbon ... 102 

 * " New View of the Origin of Dalton's Atomic Theory," p. 28. 



