LAVOISIER. 241 



riments upon the calcination of air in close vessels ; and 

 he proved clearly that the whole air and metal after 

 calcination weighed exactly the same as before, and that 

 the metal had gained in weight exactly what the air had 

 lost. But he adds an inference which is very remarkable 

 on more accounts than one. It is that the atmo- 

 sphere is composed of two gases, one capable of support- 

 ing life and flame, and of combining with metals in then- 

 calcination, the other incapable of supporting either life 

 or flame, or of combining with metals. Now here begins 

 the blame imputable to this great philosopher. His 

 paper is said in his Memoir (p. 351,) to have been read 

 at Martinmas, 1774; and to have been "remis" 10 

 May, 1777; he says, p. 366, that he had received a 

 letter from P. Beccaria, dated 12 Nov. 1774, but that his 

 own Memoir was then drawn up, and that an " Extract " 

 of it had been read at the public sitting in November. 

 He does not state whether or not the important doctrine 

 above-mentioned, on the constituent parts of the atmo- 

 sphere, was contained in that extract ; nor how long before 

 10 May, 1777, it was added to the paper. Moreover, 

 he says nothing whatever of the communication made to 

 him by Dr. Priestley, in October, 1774, of his grand dis- 

 covery of oxygen. Nor does he mention that the same 

 philosopher had, in 1772, discovered the existence of 

 azote in the atmosphere, and received, from our Royal 

 Society, the Copley medal the following year, on account 

 of his paper printed in the ' Philosophical Transactions 

 for 1772.' It is wholly impossible to believe that the 

 experiments on tin could have given M. Lavoisier any 

 light on the constitution of the atmosphere, which he had 

 not derived from his similar experiments in 1770, and 



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