President's Address. 15 



four elements, and of Paracelsus concerning the three kinds 

 of matter, were proved to be absolutely false. Boyle was 

 perhaps as much, or even more, a physicist than a chemist, 

 but he certainly rendered very great service to chemistry. 

 In fact, had he done nothing more than point out, as he 

 did forcibly, that the true aim of chemistry was neither 

 to discover the philosopher's stone nor the elixir vitce, but 

 was, by means of pure scientific research, to increase the 

 store of human knowledge, he would be entitled to be 

 honourably remembered by scientific men. Boyle, however, 

 as is well known, did far more than this — his whole life 

 indeed was devoted, and profitably devoted, to scientific re- 

 search. It is to him we owe our first correct ideas reofardins: 

 true elementary substances ; and his teachings on this subject 

 were really so important as to justify us in dating the com- 

 mencement of a new era in the history of chemical science 

 from his time. Hitherto men had either inclined to the 

 Aristotelian or Paracelsian doctrine of the elements, and had 

 regarded chemistry merely as a servant of the physician or as 

 something worse of the alchemist. Boyle, however, com- 

 pletely overthrew both of these ideas, and by so doing for- 

 warded greatly the progress of chemical science. By the 

 world in general Boyle's name is best known in connection 

 with the discovery of the well-known law — that the volume 

 of a gas varies inversely as the pressure — which rightly bears 

 his name, although a strong attempt was made, and is still 

 made, I presume, to claim the honour of the discovery of this 

 important law for a French philosopher, Mariotte. About the 

 year 1672, or about a hundred years before the discovery of 

 hydrogen was made by Cavendish, Boyle actually prepared 

 this gas. He did so by dissolving metallic iron in acid, and 

 he experimented so far with the new gas as to prove its com- 

 bustible nature. He does not seem, however, to have carried 

 his investigations much further than this point, and the 

 honour of the discovery of hydrogen is always ascribed to 

 Cavendish. Boyle, like many other great men, had a weak 

 point, and in his case this consisted in allowing his mind to 

 be unduly influenced by what perhaps I may be allowed to 

 call a pet theory. He held most tenaciously certain erroneous 



