54» DOCTRINE OF MIXED GASES. 



A fecond par- If a particle of vapour can pafs freely through the air, ei fe- y 

 ticlc may follow ^^j^^ ^^^^ j^l^^ fuccecd it at any given diftance; becaufe the 

 latter may undoubtedly purfue the track which the former has 

 already traverfed ; confequently, a feries of fuch particles, pof- 

 feffing the denfity of water, might be raifed into each perpen- 

 dicular pore of the atmofphere, by the application of a proper 

 Arr prefles upon force to the furface of a collection of water fupporting fuch an 

 water. atmofphere. Now the exiftence of fuch a force is certain ; 



becaufe when air is inje6ted into either leg of an inverted 

 fyphon containing water, it conftantly diflurbs the equilibrium 

 of this fluid; that is, the gas prefles upon the liquid, notwlth- 

 llanding the fuppofition, that the former is a vacuum to the 

 Air a perforated particles conftituting the latter. If now we combine the pof- 



piftoii, by the tulaies of the hvpothefis with the precedinj? fa6l, a column of 

 bypothefis. . , . , " T , ^ ^ J*. . . 



air, which occupies the upper part or a vefl^l containing water 



in its bottom, becomes a heavy piflon, having its fubflance 

 perforated in every diredion by pores of eafy tranfmiflion, 

 which are, at the fame time, feparated by partitions imper- 

 vious to water. After contemplating this imaginary ftru6ture 

 of the atmofpherical gas, let the reader inveftigate the confe- 

 Airnotavacuum^^^"^^^ ^^ '*> 2"^ compare them with natural events. The 

 tc vapour. impenetrable parts of the gafeous pifton would compel the 



water to afcend along its perpendicular pores ; in which it 

 would be kept duly condenfed by the prefliire of the incum- 

 bent vapour. The fpecific gravity of this column, compound, 

 ed of air and water, would exceed that of the external air ; 

 confequently the upper extremity of it would conflantly glide 

 over the edges of the veflTel into the atmofphere. Thus there 

 would happen a double lofs of water, namely, by evaporation 

 and percolation : but nothing of the kind is obfervable in na- 

 ture ; confequently the air is impenetrable to the conftituent 

 particles of water not heated to the boiling point. 

 Impenetrability The circumftanceof water not being able to penetrate air at 

 noobftacle to Jqw temperatures, is no obflacle to the chemical union of the 

 c emica union. ^^^ fubftances ; for many aqueous folutions of falts occupy 

 lefs fpace, when completed, than the materials formerly did 

 One gas not a of which they are compofed. This fa6l has been eflablithed 

 vacuum to an- by the prefent Bifliop of Llandaif ; and it proves that bodies, 

 y"^^' ^yhich are mutually impenetrable, may be fufceptible of the 



bond of chemical affinity. 



After 



