2 9'6 ^^- Pr r E ST L E Y*s Experlmenls and Obfervations 

 latefl: difcovenes, fixed air and water appear to confift of the 

 fame ingredients, namely dephlogiflicated and inflammable air. 

 However, in this change of the water we cannot be abfolutelv 

 lb re that the fame proportion of the ingredients is contained, and 

 therefore it cannot be abfolutelv determined whether the inflam- 

 mable air w^hich it contains enters wholly into the fixed air, or 

 not. Farther experiments, or a careful comparifon of thefe ex- 

 periments wath thofe made by Mr. Kirwan and others, may 

 perhaps throw fome light upon this fubjecl. Whether the com-' 

 bined fixed air comes wholly from the charcoal, or whether the 

 charcoal only fupplies the phlogifton, and the water its bafis, 

 that is, the dephlogifticated air, deferves to be inveftigated. 



Before I conclude my account of the experiments with char- 

 coal, I would obferve, that there is another in which I place 

 fome dependance, in wd:>ich, with the lofs of 178 grains of 

 charcoal, and 528 grains of w^ater, I procured 1410 ounce 

 meafures of air, of which the laft portion (for I did not exa- 

 mine the reft) contained one-fixth part of uncombined fixed 

 air. This was made in an earthen tube glazed on the outfide. 



The experiments with iron were more fatisfa£lory than thof*^; 

 with charcoal, being fubje6l to lefs variation; and it is ftill 

 more evident from them, that the inflammable air does not 

 come from the ivater^ but only from the iron^ as the quantity 

 of water expended, added to the weight of the air produced,- 

 was as nearly as could be expected in experiments of this kind, 

 found in the addition of weight gained by the iron. And- 

 though the inflammable air procured in this procefs is between 

 one-third and one-half more than can be procured from iron by^ 

 a folution in acids, the reafon may be, that much phlogifton, 

 is retained in the folutions, and therefore much more may be. 

 expelled from iron, when pure water, without any acid, takes ;i 

 the place of it. I would further obferve, that the produce of 



air, 



