Manchester Mcinoiys, Vol. Iv. (191 1 ), No. IJ). 5 



In the " New System of Chemical Philosophy" both 

 the Preface and the Dedication show that Dal ton was 

 immensely grateful for the attention his speculations 

 received in Glasgow and Edinburgh. The dedication 

 runs: — "To the Professors of the Universities and 

 other residents of Edinburgh and Glasgow who gave 

 their attention and encouragement to the Lectures on 

 Heat and Chemical Elements, delivered in those cities in 

 1807: and to the members of the Literary and Philo- 

 sophical Society of Manchester, who have uniformly 

 promoted his researches." 



An account of the theory, often referred to in this 

 series of papers, had already appeared. Thomas Thomson 

 had been so much interested and impressed by the 

 doctrine as Dalton explained it to him in 1804, that he 

 became the first convert to it. He showed as much zeal 

 in the cause as its author. With permission he gave a 

 short sketch of it in the next edition of his " System of 

 Chemistry." This was the third edition, published in 

 1807, of the most successful treatise of the day on 

 chemistry, and it had more influence, directly, in spreading 

 a knowledge of the doctrine than Dalton's own efforts. 

 It made Dalton's theory known to William Hyde 

 Wollaston in London, to Claude Louis Berthollet in 

 France, and to Amadeo Avogadro in Italy. 



Thomson found another opportunity of expounding 

 the theory in his memoir " On oxalic acid," which appeared 

 in the Philosophical Transactions of the Royal Society of 

 London in 1808. The very next paper in the Transactions 

 is one by Wollaston — on the carbonates and oxalates of 

 potassium — and he, as well as Thomson, advanced his 

 work as exemplifying and justifying Dalton's theory. 

 By these various means, Dalton's and Thomson's books, 



