LAVOISIER. 311 



that the combustion of charcoal produced it. M. 

 Lavoisier, in 1777, satisfied himself by his experiments 

 on pyrophorus formed by heating alum and carbon- 

 aceous matter together, that the union of carbonaceous 

 matter with oxygen gas produces fixed air. It is true 

 he did not complete this important inference till 1781, 

 when he showed by decisive experiments that charcoal 

 contains, beside inflammable air, water, and other im- 

 purities, a matter purely carbonaceous, and which he 

 afterwards termed carbon, which, by its union with 

 oxygen, forms fixed air, thence called by him carbonic 

 acid. But the knowledge that the something contained 

 in charcoal uniting itself with oxygen gas forms fixed 

 air, and that this fixed air is an acid, had been obtained 

 by Dr. Black, M. Lavoisier, and M. Macquer before 

 1777. On these facts he now reasoned as well as on 

 the composition of the acid of sugar, which, with other 

 vegetable acids, he considered as containing oxygen. 

 He then made his famous generalization that oxygen 

 is the acidifying principle, and from thence he gave it 

 the name. Dr. Priestley had shown its absorption by 

 the lungs in respiration ; and thus we had the general 

 proposition established, as M. Lavoisier supposed, that 

 oxygen gas is necessary to combustion, calcination, 

 acidification, respiration, possibly to the animal heat 

 thence arising, and certainly to the red colour of arte- 

 rial blood; consequently he held that all those pro- 

 cesses, so different in themselves, are really one and 

 the same, the union of oxygen with different bodies in 

 different ways. I reserve for a subsequent stage of 

 the inquiry the consideration of this important and 

 beautiful theory. 



While M. Lavoisier was employed in generalizing 

 the phenomena observed by others, in correcting former 

 opinions, and in adding materially to the store of facts 

 by his own experiments, but rather filling up blanks 

 left by his predecessors than producing any very 

 striking novelties himself, two most important disco- 



