Analyfis of the Air. 289 



bodies which ic acts upon, and thereby con- 

 iiderably augments their weight, is very evi- 

 dent in Minium or Red Lead, which is ob- 

 ferved to increaie in weight about JL part in 

 undergoing the action of the fire ; the ac- 

 quired rednefs of the Minium, indicating the 

 addition of plenty of fulphur in the opera- 

 tion : For fulphur, as it is found to act moil 

 vigouroufly on lighr, fo it is apt to reflect, 

 the flrongeft, viz. the red rays. And that 

 there is good ftore of air added to the Mi- 

 nium, I found by diftilling firfl 1922 grains 

 of Lead, from whence I obtained only icwen 

 cubick inches of air ; but from 1922 grains, 

 which was a cubick inch of Red Lead, 

 there arofe in the like fpace of time thirty- 

 four cubick inches of air ; a great part of 

 which air was doubtlefs abforbed by the 

 fulphureous particles of the fuel, in the 

 reverberatory furnace, in which the Mi- 

 nium was made; for by Experiment 106. 

 the more the fumes of a fare are confined, 

 the greater quantity of elaftick air they ab- 

 forb. 



It was therefore doubtlefs this quantity 

 1 air in the Minium, which burft the her- 

 metically fealed glafles cf the excellent Mr. 

 Boyle, when he heated the Minium contain'd 



U in 



