304 LAVOISIEK. 



his claim. I quote from his l Elemens de Chimie.' 

 " Get air" (oxygen gas,) " nous avons decouvert pres- 

 qu'en meme terns, Dr. Priestley, M. Scheele et moi." 



Now I begin this statement by observing, that as to 

 the precise time of Dr. Priestley's discovery there is no 

 doubt ; no " presqu'en meme terns ;" it was the first day 

 of August, 1774. Scheele, without knowing of his 

 discovery, made the same the year after, 1775. So far 

 then the statement of Lavoisier is incorrect; Priestley 

 and Scheele did not discover oxygen, " presqu'en 

 meme terns." But we must proceed, and shall first of 

 all examine in what way M. Lavoisier preferred his 

 claim. For that would have rested upon a foundation 

 somewhat more plausible had he brought it forward 

 early, and always adhered to the same statement. But 

 the reverse is the fact. 



We must first remark that not a hint is dropped of 

 this claim, in the paper upon calcination originally 

 presented in 1774, and afterwards with additions in 

 1777. In 1775, at Easter, he read a paper on the nature 

 of calcination, which was " relu 8 August, 1778 ;" 

 with what additions is not stated. But the experiments 

 which it contains are of two classes ; the one set he 

 says were made above a year before, or in spring 1774, 

 and these throw no new light at all on the subject; 

 the others were made, he says, first in November, 

 1774, and more fully before other persons, in the fol- 

 lowing spring. These experiments show that the 

 oxygen of the atmosphere is absorbed in calcination ; 

 and this conclusion is stated ; but no claim whatever 

 is made to the discovery of oxygen gas, although if 

 discovered by him at all, it must have been in those 

 experiments. He only calls it " the most respirable 

 portion of the atmosphere." A most important admis- 

 sion is, however, made in a subsequent paper, 1782, 

 that the experiments in which he made this step, were 

 not those performed in 1774, but those performed in 

 February, 1775, (Vol. for 1782, p. 458). In 1776 he 



