298 LAVOISIEE. 



volume for 1771. In that year, however, he resumed 

 his chemical pursuits, and applied himself to the atten- 

 tive consideration of the calcination of metals. The 

 recent discoveries on the nature of gases by Black, 

 Cavendish, and Priestley, appear to have chiefly con- 

 tributed to his doubts upon the foundation of Stahl's 

 theory, Avhich considers the union of phlogiston, or the 

 matter of heat and light, with the basis of the metals, 

 as the cause of their lustre and ductility, and the evo- 

 lution of that substance as the cause of their becoming 

 earthy, or calces. M. Lavoisier examined the process 

 by which minium, or red lead, is reduced, that is, re- 

 sumes its metallic state, and he found that there was 

 always evolved a great quantity of air, which he ex- 

 amined and found to be fixed air, being, he expressly 

 says, the same that escapes in the effervescence of 

 alkalis and calcareous earth, and in the fermentation 

 of liquors. He then examined the converse operation 

 of calcination, and found it accompanied with an ab- 

 sorption of air, and that the weight of the metal had 

 increased by the whole weight of the air absorbed. 

 The inference which he drew was, that calcination is 

 caused by the union of air with the metal, and not by 

 the loss of any body, as phlogiston, combined with it. 

 These experiments and this theory he published at 

 the end of the year 1773, in a small volume entitled 

 ' Opuscules Physiques,' which describes very fully the 

 previous discoveries on gases and on heat, and con- 

 tains many ingenious discussions on the processes of 

 calcination and combustion. He had in the course of 

 that year read several Memoirs, on the subject of his 

 own experiments, to the Academy, and had shown 

 these experiments to several of its members. Nothing, 

 therefore, can be more incontestable than his claim to 

 the important step now made the cause of so many 

 others, that the calcination of metals is their uniting 

 with a gas become fixed and solid in their substance; 

 and a mortal blow was thus given to the theory of 



