Analyfis of the Air. 287 



acquired rednefs of the Minium, indicating 

 the addition of plenty of fulphur in the o- 

 peration : For fulphur, as it is found to ad 

 moft vigoroufly on light, fo it is apt to 

 reflect the ftrongeft, viz. the red rays 5 and 

 that there is good ftore of air added to the 

 Minium, I found by diftilling firft 1922 

 grains of Lead, from whence I obtained 

 only feven cubick inches of air $ but from 

 1922 grains, which was a cubick inch of 

 Red Lead, there arofe in the like fpace of 

 time 34 cubick inches of air 5 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 io5* 

 the more the fumes of a fire are confined^ 

 the greater quantity of elaftick air they ab_ 

 forb. 



It was therefore doubtlefs this quantity 

 of air in the Minium which burft the her- 

 metically fealed glaffes of the excellent Mr. 

 Boyle, when he heated the Minium con- 

 tained in them by a burning glafs 5 but 

 the pious and learned Dr. Nieuwentp at- 

 tributes this effeft wholly to the expan- 

 lion of the fire particles lodged in the Mi* 

 % nium* 



