HISTORICAL INTRODUCTION. 13 



1, 2, 4. These facts gradually drew the atten- 

 tion of Chemists to Mr. Dalton's views, and 

 induced several to adopt them, who were at 

 first inclined to consider them as visionary. 

 Among these I may mention Sir Humphrey Davy, 

 who contributed so materially, a few years after, 

 to confirm and extend this important theory. 



In 1808 Mr. Dalton published the first 

 volume of his New System of Chemical Philo- 

 sophy. In the last chapter of that volume, 

 consisting only of six pages, he gives us a con- 

 cise view of his atomic theory ; and in a plate 

 at the end of the volume, he exhibits the sym- 

 bols and atomic weights of 37 bodies, 20 of 

 which were then considered as simple, and the 

 other 17 as compound. In 1810, the second 

 volume of this work appeared, in which he 

 examined the combinations of oxygen with hy- 

 drogen, azote, carbon, sulphur, and phosphorus ; 

 and the combinations of hydrogen with carbon, 

 sulphur and phosphorus ; and showed that all 

 these combined according to the laws of the 

 atomic theory. He also examined the atomic 

 weights and combinations of the alkalies and 

 earths. The third volume of this most impor- 

 tant work, though it has been printed for several 

 years, the author, for reasons with which I am 

 unacquainted, has thought proper to withhold 

 from the public and by so doing, has doubtless 

 lost the right which he would have enjoyed, to 



