Reviews. 165 



and ratified. The first part of vol. I. of the New System was not 

 published till 1808, and the second not till 1810. The second 

 volume did not appear till 1827. It contained in an Appendix, 

 what its author styled a " Reformed" Table of Atomic Weights, 

 in which oxygen figures as 7 : nitrogen as 5 + or 10 \ ; carbon 

 as 5-4 ; sulphur 13 or 14 ; and phosphorus as 9 ; hydrogen being- 

 regarded as unity. It is not a little remarkable that the author 

 of the atomic theory was wrong, and far wrong, in every one of his 

 atomic weights. He would accept none of the corrections of other 

 chemists, and priding himself on his practicality defended all his 

 numbers, which are now universally discarded ; but it was this 

 stubborn self-reliance which enabled him to transcend the imper- 

 fection of his self- supplied data, and by the power of his genius 

 to announce laws, which, paradoxical though it may appear, he 

 established as true, although every example of their truth he 

 offered was false. 



Dr Henry's work enables us to dispose conclusively of the 

 much-vexed question how far Dalton was anticipated by others in 

 his announcement of those laws of combining proportion by weight, 

 which obtain in chemistry. His biographer's revelations strik- 

 ingly show how difficult a task it ever is to write history faithfully, 

 and how little even the most able and friendly contemporaries of 

 a man can often be trusted in their estimate of his doings. Every 

 chemist was aware that Dalton had been anticipated in the disco • 

 very of the law of Reciprocal Proportion, by Richter (following out 

 the views of Bergman and Wenzel), not to mention the law of 

 Definite or Constant Proportion, which he did not claim as his 

 own ; and that Higgins had preceded him in regarding chemical 

 combination as occurring between the ultimate particles of bodies. 

 At the same time, it was matter of almost total uncertainty how 

 far Dalton, who read exceedingly few books, was familiar with 

 those earlier researches ; but the general impression, advocated in 

 his own behalf by Higgins, and so far favoured by Davy, was, 

 that Dalton had some acquaintance with Higgins's views, but 

 none, as Dr T. Thomson specially asserted, with those of Richter. 



It now appears that Dalton was ignorant altogether of the ex- 

 istence of Higgins or his writings, till many years after he pub- 

 lished his views on atomics ; and Dr Henry shows very distinctly 

 that though Higgins did not hesitate to hint at plagiarism, his 

 doctrines, however ingenious, are inconsistent with each other, 

 and are not based on such considerations as led Dalton to his 

 conclusions. 



On the other hand, his biographer gathered from the lips of 

 the chemist himself, that he had profoundly studied Richter's 

 tables of combining proportions before he published his Atomic 

 Theory ; but it does not less clearly appear, that before he was 

 familiar with the views of the German chemists, he had not only 



