relating to Air and Water . 305 
Willing to try the effect of heating iron, and other fub- 
flances, in all the difteient kinds of air, without any particular 
efpe&ation, I found that iron melted more readily in vitriolic 
add air than in dephlogifticated air, the air was diminilhed as 
rapidly, and the infide of the veflel was covered with a black 
footy matter , which, when expofed to heat, readily fublimed in 
the ioim of a white vapour, and left the glafs quite clean. 
The iron, after the experiment, was quite brittle, and 
muff, I prefume, be the fame thing with iron that is ful- 
johurated ; but I did not particularly examine it. Of feveiu 
ounce meafures 01 vitriolic acid air, in one of thefe experi- 
ments, not more than three-tenths of an ounce meafure re- 
mained ; of this two-thirds was fixed air, and the refiduuin 
of tins was inflammable. I had put three of fucli refiduums 
together, in order to make the experiment with the greater- 
certainty. 
Having tranfmitted Jieam, or the vapour of water, through 
a copper tube, I was willing to try the eftefts of fpirit of wine 
through the fame tube when red-hot, having before procured 
inflammable air by fending the fame vapour through a red hot 
tobacco-pipe. In this cafe, the vapour of the fpirit of wine 
had no fooner entered the hot copper tube, than I was perfedly 
aftonifhed at the rapid produaion of air. It refembled the 
blowing of a pair of bellows. But I had not ufed four ounces 
■of the fpirit of wine before I very uSexpededly found, that 
the tube was perforated in feveral places ; and prefently after- 
wards it was fo far deftroyed, that in attempting to remove it 
tiom the nre it adually fell in pieces. The infide was full of a 
black footy matter relembling lamp-black. 
Upon this I had recourfe to earthen tubes, and found, that by. 
melting -opper and other metals in them, and tranfmitting the 
Vol. LXXV. R r ° 
^ 1 vapour 
