1819.] the late Mr. Thomas Hairij. loo 



London, of whiefa he became a Fellow in May, 1775. The 

 persons most active in promoting his election were Sir John 

 Pringle and Dr. Priestley ; and he had the advantage not only 

 of the vote, but of the favourable influence of Dr. Franklin, who 

 happened at that time to be in London. Several years after- 

 wards, tire same venerable philosopher, when in the 81st year of 

 his age, presided at the meeting of the American Philosophical 

 Society, at which Mr. Henry was elected a member, and again 

 honoured him with his suffrage.* 



The writings of the celebrated Lavoisier were introduced by 

 Mr. Henry to the notice of the English reader in 1776. The 

 earliest work of that philosopher was a volume, consisting 

 partly of an historical view of the progress of pneumatic che- 

 mistry from the time of Van Helmpnt downwards ; and partly of 

 a series of original essays, which are valuable as containing the 

 germs of his future discoveries. To this work, Mr. Henry added, 

 in the notes, occasional views of the labours of contemporary 

 English chemists. A few years afterwards he translated, and 

 collected into a small volume, a series of Memoirs, communicated 

 bv M. Lavoisier to the Paris Academy of Sciences, when the 

 ■v iews of that philosopher, respecting the anti-phlogistic theory 

 of chemistry, were more fully unfolded. In undertaking the 

 translation of these works, he was influenced by a desire to 

 place within the reach of English readers, among whom the 

 knowledge of the French language was then confined to compa- 

 ratively few, the pleasure and conviction which he had himself 

 derived from those admirable models of philosophical inquiry. 



Notwithstanding the large share of professional employment 

 to which Mr. Henry had now attained, he still continued to 

 engage frequently in experimental pursuits, the results of which, 

 at this time, were communicated to the world chiefly through 

 the publications of his friends Dr. Priestlev and Dr. Percival. 

 Of these, the most important were some Experiments on the 

 Influence of Fixed Air on Vegetation, by which he endeavoured 

 to show, that though fixed air is injurious, when unmixed, to the 

 vegetation of plants, yet that when mingled in small proportion 

 with common air, it is favourable to their growth and vigour. 

 The facts established by this inquiry were communicated to 

 Dr. Priestley ; and it is creditable to the candour of that distin- 

 guished philosopher, that he was anxious to make them public, 

 not only for their general merit, but because, in one or two 

 points, the results disagreed with his own. " I am much 

 pleased," Dr. Priestley replies, "with the experiments mentioned 

 in your letter, and if you have no objection, shall be glad to 

 insert the greatest part of it in my Appendix, which I am just 

 sending to the printer's. I the rather wish it, as a few of the 

 experiments terminate differently from those that I shall publish, 



* This circumstance it stated in a letter from Dr. Rush to Mr. Henry, dated 

 Philadelphia, July 29, 1786. 



