236 LAVOISIER. 



the Government and M. Parcieux, a learned mechanical ' 

 projector, on the comparative expense of bringing the 

 water of the rivulet Yvette by canal and wheel engines, 

 or by steam engine, M. Lavoisier examined the subject, 

 and shewed that the latter mode was the most expensive. 

 His Memoir appeared in the volume for 1771. In that 

 year, however, he resumed his chemical pursuits, and 

 applied himself to the attentive consideration of the 

 calcination of metals. The recent discoveries on the 

 nature of gases by Black, Cavendish, and Priestley, ap- 

 pear to have chiefly contributed to his doubts upon the 

 foundation of Stahl's theory, which 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 duc- 

 tility, and the evolution of that substance as the cause 

 of their becoming earthy, or calces. M. Lavoisier ex- 

 amined the process by which minium, or red lead, is 

 reduced, that is, resumes its metallic state, and he found 

 that there was always evolved a great quantity of air, 

 which he examined 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 absorption 

 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 experi- 

 ments and this theory he published at the end of the 

 year 1773, in a small volume entitled 'Opuscules Physi- 

 ques/ which describes very fully the previous discoveries 



