Artalyfis of the Air. 289 
bodies which it ads upon, and thereby con- 
fiderably augments their weight, is very evi- 
dent in Minium or Red Lead, which is ob~ 
ferved to increafe in weight about T V part 
in undergoing the adion of the fire. The 
acquired rednefsof the Minium, indicating 
the addition of plenty of fulphur in the 
operation: For fulphur, as it is found to ad 
moft vigoroufly on light, fo it is apt to 
refled the ftrongeft* viz . the red rays 5 and 
that there is good (tore of air added to the 
Minium, I found by diftilling firft 192,2, 
grains of Lead , from whence I obtained 
only feven cubick inches of air 5 but from 
1 9zz grains, which was a cubick inch of 
Red Lead, there arofe in the like fpace of 
time 34 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 io< 5 » 
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 glafies of the excellent Mr. 
Boyle , when he heated the Minium con- 
U rained 
