and the f earning Convey fan of Water into Air . 405 
and it muft be ufed before it can have attta&ed any from the 
atmofphere ; and in the next place, the water alfo (a confidera- 
ble quantity of which muft be ufed, and which will alfo be 
heated in the procefs) fhould be made as free from air as poffi- 
ble. In thefe circumftances, had I found the imall refiduum, 
of 2 ounce meafures from 101, to have been phlogifticated or 
fixed air, I fhould not have been dilappointed ; and it would not 
have prevented my concluding that phlogfton was the lame 
thing with inflammable air , contained in a combined ftate in 
metals, juft as fixed air is contained in chalk and other calca- 
reous fubftances ; both being equally capable of being expelled 
again in the form of air. 
Afterwards ufing a calx of lead, which had been prepared in 
the lame manner with the former, but which had remained 
fome weeks expofed to the air, I found, that when by uling it 
I had reduced 150 ounce meafures of inflammable air to 10, 
this refiduum was phlogifticated air. But examining this calx 
Separately, I found that it gave, by heat in a glafs veflel, a 
confiderable quantity of phlogifticated air. 
I muft obferve, that the minium fhould not be reduced to a 
perfe&ly compact glafs of lead ; for then it would be too re- 
fractory to be ealily revived by this procefs. Making ufe of 
fome of it, I found that I could only melt it ; but that a co- 
pious black fume came from it, and coated the infide of the 
receiver : an experiment which I fhall repeat and re-confider. 
I muft alfo obierve, that the lead which I procured in the 
above-mentioned procefs was not to be diftinguifhed from any 
other lead, and that the inflammable air was all procured from 
iron by oil of vitriol. 
When I made ufe of inflammable air from wood, I found, 
that though I was able to reduce minium with it, it was 
effected 
