Anal'yfts of the Air. 287 
acquired redneft of the Minium, indicating 
the addition of plenty of fulphur in the o- 
peration : For fulphur, as it is found to aft 
moft vigoroufly on light , fo it is apt to 
I refledf the ftrongeft, viz. the red rays ; and 
I 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 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 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 hcr- 
I metically fealed glaffes of the excellent Mr. 
Boyle, when he heated the Minium con- 
I tained in them by a burning glafs ; but 
the pious and learned Dr. NiewSuentyt at- 
tributes this effeff wholly to the expan- 
fion of the fire particles lodged in the Mi- 
5 nium. 
