3G6 On Ike Origin of the Atomic Theory ^ 



mistry to tlie labours of Margraaf, Bergman, and Sclieele. Kir-* 

 wan, Bergman, and Wenzel distinguished themselves by the 

 analyses of the salts. Tliey ascertained that salts and all com- 

 pound bodies are united constantly in the same proportions of 

 their constituents. 



The foregoing philosophers had written long before me; and 

 I challenge Dr. Thomson to produce a single page from their 

 respective works that relates to the atomic theory, or, in other 

 words, to the definite proportions in which elementary particles 

 unite so as to form atoms and molecules. 



From the foregoing philosophers the Doctor passes to Richter, 

 ■who analysed saline bodies with still greater accuracy than his 

 predecessors. He ascertained the Cjuantitv of the earths and 

 alkalies necessary to saturate 100 parts of different acids. As 

 the labours of this chemist do not relate to the atomic theory, I 

 consider it unnecessary to attend to them minutely. 



Had Dr. Thomson been a faithful and unprejudiced historian, 

 he would have had the candour to mention my Comparative 

 View, and the discovery of the atomic theory, before he brought 

 forward the labours of llichter, which were subse(juent to mine. 



Next in the order of this curious history, Proust (no doubt a 

 chemist of considerable merit) is introduced. From the great 

 attention which he paid to metallic oxides, he was able to prove 

 that every metal is capable of forming a certain determinate 

 number of oxides, and no more. " Tims, zinc unites but to one 

 dose of oxygen ; consequently there is but one oxide of that 

 metal : iron, arsenic and antimony form two each : tin forms 

 three." 



In my Comparative Vitw, written many ^ears before the work 

 of Proust, it will be found that I considered metals in general 

 to be capable of uniting to different doses of oxygen, and that 

 th.e force of union was in the inverse ratio of the numl)er of doses 

 which they took in*. I mention these circumstances merely 

 to show tliat I developed principles only, for I had not attended 

 to the different doses of oxygen to which the different metals 

 were capable of uniting. These circumstances ought to have 

 been mentioned : but this would frustrate the Doctor's purpose, 

 that of bringing Dalton in as an original discoverer of the atomic 

 theory. 



" Such was the state of the subject," continues the Doctor, 

 *' when Mr. Dalton turned his attention to the combinations of 

 bodies with each other, al)out the year 1804." Mr. Dalton's 

 first volume of the Atomic Theory made its appearance in 1 808. 



* I refer to my Comparative View, or to my Atomic Theory, on this 

 subject. 



The 



