New Theory of the Confi'Uution of mixed 4eriform Fluids. 643 



pf its own kind : that is, the preflure upon a particle of A will be equal . 30 inches 



OT -f- « 



of mercury ; and that upon a particle of .P n . 30 inches ; thofe preffures arifing 



fokly from the particles of their own kind. 



On the fourth hypothefis, where two elaftic fluids meet, wbofe particles, inftead of re- 

 pelling, attradt one another ; that is, the particles of ^ attra£l thofe oi B : then, two or 

 more particles coalefcing, a compound will be formed pofleffing peculiar properties. Here, 

 if the compound happen to be an elaftic fluid in that temperature, m mcafures of ^and « 

 meafures of B, will occupy a fpace lefs than m ■{- n meafures, and the new fluid be of 

 greater fpecific gravity than the other two: this at leafl would moft probably be the cafe. 



To underftand thefe dedudlions from the preceding hypothefes may perhaps require the 

 aid of mathematical reafoning ; but I think they will be moftly pretty obvious to fuch as ar« 

 in fome degree converfant in thefe fubje<5t3 : I fhall therefore proceed to the application j 

 that is, to confider which of thofe hypothefes will beft explain eftablifhed fa£ts. When two 

 gafesofvery different fpecific gravities arc confined in the fame vefTcl, for inftance ths 

 oxigenous and hidrogenous, they are ever found to be jointly difFufed through the whole 

 capacity of the vefTel, difregarding the laws of hydroftatics. Again, with refpe£t to elaftic 

 vapours from liquids; aqueous vapour under 212°, cannot poffibly fupport a preiTure equal 

 to that of the atmofphere; vapour from alcohol requires 175°, and that from aether 100 or 

 105°, in order to be formed at all under a prefTure of 30 inches of mercury; yet we fee 

 all thefe liquids evaporate daily in the open air, and at low temperatures. It is impofTible 

 to reconcile the firft of thefe fa£ls to either the firft or fecond hypothefis; as for the fecond 

 fa£l:, we attempt to reconcile it to them by another hypothefis; namely^ thac one or all of 

 the gafes conftituting the atmofphere, aft as a general menftruum, and dilTolve liquids in- 

 difcriminately in greater or lefs degiee. But this explanation is not without fome difficul- 

 ties ; for the fpecific gravity of the gafes is dimini/hed by this procefs, inftead of being /'«- 

 creafed, and heat is abforbed by the liquid difTolved, juft the fame as if it were changed into 

 a diftinfl elaftic fluid. 



If we adopt the third hypothefis, the explanation of both thefe fa£ts, and indeed of every 

 other, becomes at once eafy and perfedlly intelligible. The intimate mixture and difTufion 

 of gafes of whatever fpecific gravity, is a necelTary confequence : the vapour of water, and 

 of every other fluid which does not chemically unite to the azotic and oxigenous gafes of 

 the atmofphere, nor to one another, may exift as fo many diftindl fluids in every tempe- 

 rature of the atmofphere, and without any regard to its prefTure on the furface of the earih, 

 being totally uninfluenced by any other prefTure than that arifing from the weight of their 

 own particles : in (hort each vapour, in regard to prefigure, is in the fame circumftances as 

 if it were the only elaftic fluid conftituting the atmofphere. 



Many other fafts which arc difficultly explicable upon any other hypothefis, are readily 

 juiderftood upon this. When a portion of atmofpheric air is fubjcded to a folution of 



I i a fulphurct 



