the Tube that was within it, was firft preffed full of 
Brafs Duft which I had the conveniency to do by 
means of a Brafs Cap, which fcrew’d on to the end, not 
before mentioned. This Brafs Duft I moiftned with a 
little Water, thinking 'thereby to exert a more than or- 
dinary Steam, or Effluvia, from the Mettal, which the 
Air might take along with it, as it pafs’d through fuch 
ftrait and narrow Avenues, as it muft do between the 
Brafs Duft. In this manner it was put into the Water 
/vvben Cold, and continued in it till it had boil’d a con- 
fiderable time 5 hy which means it muft, in all its Parts, be 
of the fame Degree of Heat (at leaft) as the boiling Water. 
Thus it was taken out, and applied to the exhaufted 
Receiver^ where, upon turning a Cock, I gave the liber* 
ty for that Air oply to pafs into it, which muft fucceed 
through the Brafs Box and Duft, under the Circumftances 
before mentioned. When the Receiver was full of this 
Air, the Cover was taken off, and a lighted Candle 
plung’d into it, where it continued burning, even at 
the bottom, as if it had pafs’d through no fuch Medi- 
um, but had been full of Common Air. I took that 
Method to try it, believing the Flame of a Candle to 
be the moft tender way of difeovering a Change in 
Air. Afterwards I repeated the fame Experiment over 
again, with dry Brafs Duft inftead of the former 5 but 
the Succefs was the fame. Therefore it feems to me, 
that fuch a Degree of Heat, as that of boiling Water, 
is not fufficient to caufe any confiderable Change fif 
any at all) in the Air 5 nor fuch a Degree of Heat, 
able to ftrike any Injurious, or fuflocating Effluvia, out 
of the Metalline Particles. 
