rciaiing to u'fir and JVc2ter. 299 



Cv)!vrideimg how little this inflammable ah* weighs, viz, the 

 V hole 1054 ounce meafures not more than 63 grains, and the 

 difficulty of afcertaining the lofs of water to fo fmall a quan- 

 tity as this, it is not poffible to determine, from a procefs of 

 this kind, how much water enters into the compofition of the 

 inflammable air of metals. It would be more eafy to deter- 

 mine this circumllance with refpe«£l to the inflammable air of 

 charcoal, efpecially by means of the experiment made with a 

 burning lens /// vacuo. In this method two grains of charcoal 

 gave at a medium thirteen ounce meafures of inflammable air, 

 which, in the proportion of 30 ounce meaiures to 8 grains, 

 will weigh 3.3 grains; fo that water in the compofition of this 

 kind of inflammable air is in the proportion of r .3 to 2, though 

 there will be fome difficulty with refpe(5t to the fixed air inti- 

 mately combined with this kind of inflammable air. 



Since iron gains the lame addition of weight by m.elting in 

 (JUphlogiJlicated air, and alfo by the addition of water when 

 red-hot, and becomes, as I have already obferved, in all re- 

 fpe^lsthe fame fubftance, it is evident, that this air or water, as 

 exifting in the iron, is the very fame thing ; and this can 

 hardly be explained but upon the fuppofition that water confifts 

 of two kinds of air ; viz, inflammable and dephlogifticated. 

 I fliall endeavour to explain thefe procefles in the following 

 manner. 



When iron is melted in dephlogifticated air, we may fuppofe 

 that, though part of its phlogifton efcapes, to enter into the 

 compofition of the Imall quantity of fixed air which is then 

 procured, yet enough remains to form water with the addition 

 of dephlogiificated air which it has imbibed, (o that this calx 

 of iron conlifts of the intimate union of the pure earth of irofi 

 and of water ; and therefore when the fame calx, thus fatu- 



q 3 rated 



