242 LAVOISIER. 



1771, upon the reduction of minium, and the calcination 

 of other metals. But the discoveries of Dr. Priestley must 

 have been known to him in 1774 ; and what he gives as 

 conjectures derived from his own experiments, were the 

 discoveries of Dr. Priestley in 1772 and 1774. The 

 knowledge of these discoveries formed the only difference 

 between the state of M. Lavoisier's information, when he 

 experimented upon tin in 1774, and when he experi- 

 mented on lead three years before. It is perfectly clear that 

 until the discoveries of Dr. Priestley, the chief of which, 

 we have positive evidence, was communicated to him by 

 the Doctor himself, he never had the least idea of the air 

 absorbed in calcination possessing any qualities like 

 those of oxygen gas, or that the air evolved in the reduc- 

 tion of calcined metals, was of that nature^ indeed, he 

 distinctly stated it to be fixed air, misled by the quantity 

 of fixed air found in minium as an impurity. He had 

 made many experiments on calces of metals, and he had 

 never found any air to be contained in them resembling 

 oxygen. Until he heard of Dr. Priestle/s great experi- 

 ment he never had thought of obtaining oxygen gas from 

 those bodies, nor ever knew of the existence of that gas. 



This is the plain inference from the history of his 

 inquiries, as far as we have now followed it. But as he 

 has himself, beside wrapping up the date of his theory 

 in the general terms already observed when he presented 

 his paper on tin, also laid positive claim to the discovery 

 of oxygen in a subsequent Memoir, it becomes necessary 

 to examine the grounds of this pretension more closely, 

 and we shall find that this examination entirely confirms 

 the position already stated, namely, his ignorance of 

 oxygen, until the true discoverer made him acquainted 

 with it. 



