out MIXED GASaS* ^ 



Memoirs, with this resen'ation, that the concession is made. Examination of 

 merely for the purpose of shewing such a combination to be Mr. Dalton's 

 imompatib'e with the usal coarse of things, for a moment ; g/ga^^ *"^^* 

 which being demonstrated, the inutihty of the fundamental 

 iypothe>is Will follow, as a necessary consequence.—^To give 

 a concise view of Mr. Dalton's general notion of the subject, 

 we are to suppose a number of distinct gases to be confined 

 in a space comnvon to them all; which space may be circum- 

 scribed by the concave surface of a vessel, or the compressing 

 power of an exiernal fluid : besides this, we must imagine the 

 constituent pariitles of each individuel gas to be actuated by 

 a mutual repulsion, while, at the same time, they remain per- 

 fectly indifferent to the particles which compose the other fluids 

 that are confined in the common space ; in short, we are to 

 conceive, that the particles of each gas act upf n those of their 

 own kind in the manner of elastic bodies; but that they obey 

 the laws of inelastic bodies, as often as they interfere with 

 corpuscles of a different denomination. After premising the 

 preceding particulars, we may conceive a certain arrangement 

 of the elementary parts of a fluid mixture, in which the ad- 

 justement of the whole shall be of^ description which wiU 

 form, from particles of any one denomination, a homogeneous 

 fluid, possessing its own separateequilibrium ; consequently, 

 €8ch gas will exist as an independant being, and exercise the 

 functions of its elasticity, just as if all the other fluids were 

 withdrawn fi-om the commoh space. This systematic arran- 

 gement in an assemblage of gaseous substances cannot be 

 maintained, unless one particuUr method of disposing its com- 

 ponent parts be observed ; with consists in that distribution of 

 the elements which will produce a separate equ'librium in the 

 fluid composed by the elementary corpuscles of each denomi- 

 nation , consequently, the equilibrium in question cannot take 

 place unles the necessary disposition of the heterogeneous 

 particles be first established ; so that the formeV requisite of the 

 theory is entirely depended on the latter. — After having ac- 

 quired a distinct idea of a fluid mixture, composed of gases 

 possessing separate equilibria, v/e come in the next place to 

 investigate the mechanical properties of such a compound ; in 

 ihe prosecution of which enquiry, the comparative densities 

 of the constituent fluids must be first determined in a horizon- 

 tal plane, the situation of which is given in the cowimon space, 



B3 



