of Atmospherical Air, &c. 159 
these circumstances, than I perceived the air to di- 
minish, and, at the same time, the inside of the ves- 
sel to grow very cloudy with particles of dew, that 
covered almost the whole of it; and, by degrees, ga- 
thered into drops and ran down the sides of the ves- 
sel, &c. Thus, at one time, I made a piece of 
this slag imbibe 5.5 ounce-measures of inflammable 
air, while it lost as much as the weight of about 
three ounce-measures of dephlogisticated air; and 
the water collected (by means of bibulous paper) 
weighed two grains.* Another time, a piece of 
slag lost 1.5 grains, and the water produced, was 1.7 
grains.” Nothing can be more plain and decisive. 
The iron, which had become a calx by combining 
with oxygen, was reduced to its metallic state, not 
by imbibing any thing, but by being deprived of its 
oxygen, which uniting with the hydrogen of the in- 
flammable air, formed water, equal in weight to both 
the hydrogen and oxygen as nearly as possible : parti- 
cularly when it is considered, that some loss must 
have taken place by the manner in which the water 
was collected. Chemistry is grcatly indebted to Dr. 
Priestley for his experiments on iron heated in oxy- 
genous gas, and the reduction of the oxyd by in- 
flammable air. Nothing can be more beautiful and 
simple; and if there were no other experiments on 
the subject, these alone would be sufficient to esta- 
* This is above a quarter of agrain more than the iron lost. 
