420 PHILOSOPHICAL TRANSACTIONS. [aNNO 1788. 



means an improbable supposition, though we are not yet in possession of any 

 process by which it may be done. It is pretty evident that, in this respect, 

 nature actually does what we are not able to do. 



Further, that the doctrine of the decomposition of water being set aside, that 

 of phlogiston (which, in consequence of the late experiments on water, has 

 been almost universally abandoned) will much better stand its ground, as all the 

 newly discovered facts are more easily explained by the help of it. If water be 

 not decomposed, both metals and sulphur do certainly yield inflammable air, 

 when steam is made to pass over them in a red heat. They cannot therefore be 

 simple substances, as the antiphlogistic theory makes them to be. Also, the 

 same thing that they have parted with, viz. inflammable air (or rather some- 

 thing that is left of inflammable air when the water is taken from it, and which 

 may as well be called phlogiston as any thing else) may be transferred to other 

 substances, and thus contribute to form any of the metals, sulphur, phosphorus, 

 or any thing else that has been deemed to contain phlogiston. This phlogiston 

 also, no doubt, having weight, it perfectly corresponds to the definition of a 

 substance, having certain affinities, by means of which it is transferred from one 

 body to another, as much as the different acids. The discovery that the greatest 

 part of the weight of inflammable air, as well as of other kinds of air, is water, 

 does not make the use of the term phlogiston less proper: for it may be still 

 given to that principle, or thing, which, when added to water, makes it to be 

 inflammable air; as the term oxygenous principle may be given to that thing which, 

 when it is incorporated with water, makes dephlogisticated air. As there is some- 

 thing in dephlogisticated air that seems to be the principle of universal acidity, 

 so I am still inclined to think, as I observed in my last volume of experiments, 

 that phlogiston is the principle of alkalinity, if such a term may be used ; espe- 

 cially as alkaline air may be converted into inflammable air. 



In the course of experiments recited in this paper, I discovered more completely 

 than before the source of my former mistake, in supposing that fixed air was a 

 necessary part of the produce of red lead, and also of manganese. Both these 

 substances, I find, give of themselves only dephlogisticated air, and that of the 

 purest kind; and all the fixed air they yielded in my former experiments must 

 have come from the gun-barrel I then made use of, which would yield inflamma- 

 bleair, which, withdephlogisticatedair,formsfixedair. For though the dephlogisti- 

 cated air from red lead was so pure that, mixed with 1, measures of nitrous air, 

 the 3 measures were reduced to 500th parts of a measure, and the substance 

 gave no fixed air at all when it was heated in an earthen tube or retort; yet by 

 mixing iron filings with it, or with manganese, as I had formerly done with red 

 precipitate, I got more or less fixed air at pleasure, and sometimes no dephlogisti- 

 cated air at all. 



