54 



Art. VII. A Translation of Rey's Essays on the Cal- 

 cination of Metals, &c. 

 [Communicated by John George Ciiiluren, Esq. F. R. S., ^c] 

 Continued from Vol. XI. p. 271. 



Essay XI. 



Air is rendered heavier by the separation of its lighter farts. 



In discussing the third method by which air becomes 

 heavier, namely, by the separation of its hghter parts, I begin 

 with this incontrovertible truth, that if from any thing its 

 lighter parts be taken away, the remainder will be heavier ; I 

 do not say that it will be heavier than the whole original quan- 

 tity, but than a portion of it equal in bulk to the remainder. 

 Separate the silver which that knave of a goldsmith mixed 

 with the gold in King Hiero's crown, the remaining gold will 

 be heavier than an equal portion of the entire crown ; what in 

 this case you do by art, nature effects by her industry, having 

 no other tool but heat, which serves her worthily in the work. 

 Observe the preparers of salt, who receive the sea water into 

 their pans, through canals ; they know that the sun's heat subtil- 

 izing the water, will sublime it into air, leaving them the salt, the 

 heavier part, at the bottom. The alchymist, true ape of nature, 

 desirous to imitate her, places his infusion of rhubarb over a chaf- 

 ing dish, that the liquor exhaling the extract may remain behind. 

 But if he want that part, which being subtilized, flies off, he 

 stops it by the way, (sly fellow as he is) (Cauteleux qu'il est, J 

 by means of the heat which he applies to his alembic. By 

 this scheme he obtains the brandy, which is lighter than the 

 wine, from which it rises, and the wine lighter than the lees re- 

 maining after the whole distillation. In this manner heat acts 

 on all sorts of liquors, rarefying some parts, thickening others, 

 and always separating them by the difference it occasions in 

 their respective weights, (par peser plus ou moins.) It pro- 

 duces the same effects on air; to observe which, turn your 

 face, I beg, towards that plain over which the sun has all the 

 day darted his rays. You think, I wager, that the air which is 



