the Philosophical Character ofDr Priestley. 13 



that combustion is not necessarily accompanied with an absorp- 

 tion of oxygen, and that acids exist independently of oxygen, 

 regarded by him as the general acidifying principle. But after 

 all the deductions that can justly be made on that account 

 from the merits of Lavoisier, he must still hold one of the 

 highest places among those illustrious men, who have advanced 

 chemistry to its present rank among the physical sciences. It 

 is deeply to be lamented that his fame, otherwise unsullied, 

 should have been stained by his want of candour and justice 

 to Dr Priestley, in appropriating to himself the discovery of 

 oxygen gas. This charge, often preferred and never answered, 

 would not have been revived in this place, but for the claim 

 so recently and indiscreetly advanced by M. Victor Cousin. 

 To the credit of Dr Priestley it may be observed, that in 

 asserting his own right, he exercised more forbearance than 

 could reasonably have been expected under such circumstances. 

 In an unpublished letter to a friend, he thus alludes to the 

 subject of M. Lavoisier's plagiarism. " He,*" (M. Lavoisier) 

 " is an Intendant of the Finances^ and has much public 

 business, but finds leisure for various philosophical pursuits, 

 for which he is exceedingly well qualified. He ought to have 

 acknowledged that my giving him an account of the air I had 

 got from Mercurius Calcinatus, and buying a quantity of M. 

 Cadet while I was at Paris, led him to try what air it yielded, 

 which he did presently after I left. I have, however, barely 

 hinted at this in my second volume.*""' The communication 

 alluded to was made by Dr Priestley to M. Lavoisier in October 

 1774 ; and the memoir, in which the latter assumes to himself 

 the discovery that mercurius calcinatus (red oxide of mercury) 

 affords oxygen gas when distilled per se, was not read to the 

 Academy of Sciences before April 1775 -f-. In evincing so little 

 irritability about his own claim, and leaving its vindication with 

 calm and just confidence to posterity, the English philosopher 

 has lost nothing of the honour of that discovery, which is now 

 awarded to him, by men of science of every country, as solely 

 and undividedly his own. 



• Letter to the late Mr Henry, dated Calne, December 31. 1776. 

 t See an Abstract of this Memoir in the Journal de Rozier, Mai 1773. 



