Ou (he Theory of Mixed Gase€. 4i21 



repulsive force of the p;irticle that .sustains flip 

 superior column. 



I'hc truth of the niaxan I'^iiiy, thus esta- 

 blished, upon the axioms of Mechanics, it 

 must be used in the next, place tp dis^pver the 

 least adventitious fprcc, which i j^^n enlarge 

 the porx^s of a gas,, by increasing the distance 

 of the contiguous particles. 



It is evident, that during the mutual scj)a- 

 ration of the corpuscles, each superior particfle 

 must jr^cedc more qr less from the particle, 

 whicb-.Jiess .immediately under, it; that is, it 

 must ascend in opposition to its natural pro- 

 pensity to descend. Now the power, which 

 urges a corpuscle upwards, exceeds its original 

 bias downwards j;- because when a body is 

 actuated by t wo ,^<;x)ntrary forces^,; it always 

 moves in the direction, of the stronger., , Con- 

 sequently the least adventitious force, that can 

 enlarge the pores of a gas, must somewhat 

 ^Ujpass the pressure, which urges the particles 

 of rttjt, downwards: but-lhis pressure on any 

 particular particle consists o^ t^e, collective 

 yve:ights of all the incumbent particli?s. Hence 

 it appears, that vapour, which enters a gas, 

 has something to contend with besides the vis 

 inertix of a number of minute. atoms : it must 

 overcome the forC|e, of gravity, upon the whole 

 iiuid j that is, it .nfj^i^ acquirp- ii; bj^^jling^J^oari 

 3 o2 



