On the Atomic Theory . 171 



than Lavoisier himself had done ; yet, as it originated with him, 

 it belongs to him of right, and to him alone. 



No person can prove that Mr. Dalton has made any novel or 

 original addition to my Theory, except extending fancifully and 

 hypothetically my relative weights of the ultimate particles of 

 elementary matter, without sufficient proof to support his con- 

 jectures ; at the same time that it is within the reach of accurate 

 experimental knowledge to confirm the principles which I 

 broached. As to the relative weights or relative quantities of 

 matter in elementary particles, I cautiously confined myself to 

 few instances, and those few will be found correct. They were 

 deduced from the relative weights of simple and compound gases; 

 and I have pointed out exceptions, even to this mode of pro- 

 cedure : Instance, — nitrous air is lighter than the gaseous oxide 

 of azote, and yet the atoms of the former are heavier than those 

 of the latter ; and I have lately pointed out that the particles of 

 azote are nearly twice the weight of those of oxygen, although 

 an equal volume of the latter gas is specifically heavier than that 

 of azotic g."53. I attributed these differences to the distances to 

 -which their particles or atoms are removed from each other by 

 their respective atmospheres of caloric. 



The relative proportions of ultimate particles in atoms and 

 molecules were illustrated by many examples in my Comp. View, 

 which constitutes another essential part of my system. The next 

 and the most important part of my doctrine relates to the rela- 

 tive forces with which ultimate particles and atoms unite to each 

 other singly, and the modification of this law when they unite 

 1 and 2, or I and 3, or I and 4, &c. Were I to leave out this 

 part, I could accomplish nothing decisive in my arduous investi- 

 gation ; and it enabled me to acconnt for many phaenomena and 

 operations in chemistry which would otherwise be inexplicable. 



The foregoing principles aggregately, but particularly the latter 

 part, enabled me " to place chemistry on the same ground with 

 that on which the discovery of the laws of gravity placed the 

 science of astronomy." 



This last link of my Theory Dalton overlooked altogether. I 

 suppose he considered it too marked a feature to bring forward. 

 But forward it must come, or else the Atomic Theory must re- 

 main a mere lauble. 



In taking a cursory view, a few days ago, of the last edition 

 (the fifth) of Dr. Thomson's System of Chemistry, I found that 

 he transferred my Atomic Theory to Dalton, without even men- 

 tioning my name ; and, what is extraordinary, adduces as an ex- 

 ample, my proportions of azote and oxygen in the different com- 

 pounds of those elements*. The Doctor also gives some ex- 

 • Vol. iii j). 19. 



periments 



