302 LAVOISIER. 



more care, he would have made the discovery in 1773, 

 which he did a few years later ; and as he then was 

 occupied in considering the nature of the diamond, its 

 identity with carbon would not have escaped him as it 

 afterwards did when he first ascertained the composi- 

 tion of fixed air. 



In 1773, M. Lavoisier made some very accurate 

 experiments upon the calcination of tin in close ves- 

 sels ; 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 atmosphere is composed of two gases, one capable 

 of supporting life and flame, and of combining with 

 metals in their calcination, the other incapable of sup- 

 porting 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 " relit" 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 con- 

 stituent parts of the atmosphere, was contained in that 

 extract; nor how long before 10 May, 1777, it was 

 added to the paper. Moreover, he says nothing what- 

 ever of the communication made to him by Dr. Priest- 

 ley, in October, 1774, of his grand discovery of oxy- 

 gen. Nor does he mention that the same philosopher 

 had, in 1772, discovered the existence of azote in the 

 atmosphere, and received, from our Koyal 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 ex- 

 periments on tin could have given M. Lavoisier any 



