( 101 ) 
Therefore the following Queries feem to offer thera- 
felves. 
Query i. Whether Air itfelf may fo fuffer in its own 
Nature, by any fort of Fire, as to be diverted of 
the Power of fubfifting Life or Flame ; Or, 
Query 2. Whether the Effluvia , or Steems, proceeding! 
from the red hot Mettals, which the Air may take 
along with it in its Paffage near them, do not 
very much contribute, if not wholly occalion the 
Effeft.. 
If the latter takes place, I prefume it may in fome 
meafure be applied to account for the Effett, that the. 
Damps, or Steems, which arife from Subterraneous Ca-t 
verns, impregnated with M^ttaline Effluvia , have on the 
Lives of Animals : And yet at* the lame time,, the fame. 
Air way fuffer no Change in refped to its other Proper- 
ties, I mean its Elafticiry and Specifick Gravity, in com- 
pari fion with other Air in the fame Region.. 
Experiments concerning the Effect of Air paf/d thro* a- 
Degree of Heat , equal to that of boiling iVaten 
I Contriv’d a Brafs Box, about 4 Inches long, and am 
inch and half over : Atone end, which I foder’d: 
up, I fix’d two frnall Brafs Tubes 5 one of which, went' 
thro’, and reach’d the Remoter end nearly 5 the other/ 
Tube was but juft inferted in if,, but each of them long', 
enough to reach fufficiently above the Surface of the 
Water in which they were to be put- Thefe Tubes* 
were to convey the Air into a Receiver exhaufted of. its: 
Air : It pafs’d firft into that Tube which nearly reach’d! 
its oppofite end, and fo into the other which lead 
the exhaufted Receiver. But the Box, with that part of 
