relating to Air dnd IVatcr, 30 r 



of moijlure came over, but a prodigious quaniity of alr^ and 

 the rapidity of its produftion aflonifhcd me ; fo that 1 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 dephlogiflicated air; for the greateft 

 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, affecled the 

 hot charcoal as it would have done if it had been applied to it 

 in the {oimoi Jham 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 fubjecl to variations. 

 In one procefs with charcoal and fcales of iron, the firfi: pro- 

 duce contained one-fifth of uncombined fixed air, the middle 

 part one-tenth, and the lafl 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, I do not pretend perfe(ftly to underftand. There is, in- 

 deed, an obvious difference in the circumftances of the two 

 experiments ; as in that with charcoal the phlogifton is found 

 in a combined flate ; whereas in that of inflammable air, it is 



loofe. 



