i^S Mr. Delnva! on the Caiije of the 



i^ntity of'thofeTubtilcprinciples can fcarcely be 

 doubted. 



White metallic calces, fuch^as the magiftery of 

 bifrnuth, and the cryftals and folutions of filver, 

 mercury, and lead, are turned black by the in- 

 flamnriable principle, which they acquire from the 

 fun's light, as well as from phlogiflic vapours. 

 And calcined ferruginous earths, which do not 

 obey the magnet, become fubjcifl to its attraftion, 

 after they have been impregnated with phlogifton, 

 by light colleded in the focus of a burning glafs. 



It is certain that vegetables receive, from the 

 rays of light, all that ftore of infiammable matter 

 with which they are fo richly fupplied. 



This principle cannot be furniflied by the^arth, 

 asthe fmall quantity of it, which the foil contains, 

 is inadequate to the efFevft: and even this fmall 

 portion is produced from the decompofition of 

 vegetables, or animals which have derived their 

 nourifhment from vegetables. Plants which, dur- 

 ing their growth, are excluded from the folar lighr^ 

 abound in aqueous juices, but are deficient in oilsi 

 and other phlogiftic products: and the privation 

 of their other qualities, fuch as odour, tafte, and 

 colour, fliews that the matter of light isefifential to 

 the vigour and perfedion of vegetable fubilances. 



Sir Ifaac Newton was of opinion that " Grof§ 

 ** bodies and light are convertible into one ano- 

 f^ ther, ^nd that bodies receive much of the4r 



** a^ivity 



