relating to Air and Water . 301 
of moijlure came over, but a prodigious quantity of air, and 
the rapidity of its production aftonifhed me ; fo that I had no 
doubt but that the weight of the air would have been equal to 
the lofs of weight both in the fcales and in the charcoal ; and 
when I examined the air, which I repeatedly did, I found it to 
contain one-tenth of fixed air, and the inflammable air,, which 
remained when the fixed air was feparated from it, was of a 
very remarkable kind, being quite as heavy as common air. 
The reafon of this was fufficiently apparent when it was de- 
compofed by means of dephlogifticated air ; for the greatefl 
part of it was fixed air. 
The theory of this procefs I imagine to be, that the phlo- 
gifton from the charcoal reviving the iron, the water with 
which it had been faturated, being now fet loofe, affe&ed the 
hot charcoal as it would have done if it had been applied to it 
in the formo tjieam as in the preceding experiments; and there- 
fore the air produced in thefe two different modes have a near 
refemblance to each other, each containing fixed air, both com- 
bined and uncombined, though in different proportions ; and 
in both the cafes I found thefe proportions fubject to variations. 
In one procefs with charcoal and fcales of iron, the firff pro- 
duce contained one-fifth of uncombined fixed air, the middle 
part one-tenth, and the laffc none at all. But in all thefe cafes 
the proportion of combined fixed air varied very little. 
Why air and not water fhould be produced in this cafe, as 
well as in the preceding, when the iron is equally revived in 
both, Ido not pretend perfectly to underftand. There is, in- 
deed, an obvious difference in the circumffances of the two 
experiments ; as in that with charcoal the phlogifton is found 
in a combined ftate ; whereas in that of inflammable air, it is 
loofe. 
