8 MeldrUM, Development of the Atomic Theory. 



Dalton. This is no small merit, for the said principle is 

 the central idea of all the atomic weight systems of the 

 nineteenth century. 



It is, however, a great mistake to suppose that this 

 conclusion exhausts the subject of the merits of the two 

 chemists. Humphry Davy, years after his declaration on 

 behalf of William Higgins, saw that there was something 

 more to be said. He recognised the claims of Bryan 

 Higgins: — " It is difficult not to allow the merits of prior 

 conception, as well as of very ingenious illustration, to the 

 elder writer." ^ He said, further, " Let the merit of dis- 

 covery be bestowed where it is due, and Mr. Dalton will 

 be still pre-eminent in the history of the theory of definite 

 proportions." ^" 



It is true on the one hand, that William Higgins was 

 much indebted to Bryan Higgins, and on the other hand, 

 that he left the atomic theory capable of infinite develop- 

 ment by other chemists. It can be urged against him 

 that he did not work out the practical consequences of his 

 ideas. Why did he not make use of his ideas as a guide 

 in experimental work? It might be supposed that he did 

 not attach much importance to them, or he would surely 

 have made strenuous exertions to establish them experi- 

 mentally, and to make them known. But, as a matter of 

 fact, there is nothing in his writings to show that he had 

 anything but a high opinion of his theory. In the year 

 1799, seizing the opportunity of the publication of a book 

 of his on bleaching, to draw attention to his system of 

 chemistry, he declared that he had "connected the whole, 

 and reduced it to a system, and made use of demonstrations 

 which, in his opinion, are not to be invalidated or contra- 



" Davy's Works, 7, 93. 

 1" Op. cit., p. 96. 



