JOURNAL 



O F 



NATURAL PHILOSOPHY, CHEMISTRY,. 



AN D,- 



THE ARTS. 



OCTOBER, 1801. 



ARTICLE L 



, New. Theory of the. Conjl'itution of mixed Aeriform Fluids, and particularly of the Aimofphet'fi' 



By Mr. JoHsD ALTOS. 



To Mr. NICHOLSON; 

 SIR,, 



Ai 



bT the period when the mechanicalproperties of the air were firft afcertained, by the 

 invention of the air-pump, ^r. the atmofphere wao undcrflood to be a homogeneous fluidj ■ 

 exclufively poffeffing the property of permanent elafticiiy. Experiment determined that 

 the elaftic force of air. was accurately as its denfity, in a given temperature. This fait 

 afforded a datum from which the law of repulfion of the corpufcles of air could be calcu- 

 lated. Accordingly Newton demonftrated, ( Principia Prop. 2^, B. 2,) that an homogt' 

 7ieous elaflic fluid pojfejjlng. a force in proportion ta its denftty. is . conjiituted of particles repelling 

 each other by a force decreaftng dire£l!y as the diflimce of the centres of the particles from each 

 other. This refult is, I believe, univerfally allowed as unqueftionable. Modern chemiftry 

 however, demonftrates that the atmofphere is not zw homogeneous fluid; it is conftituted ^ 

 of _/^xii'»fl/ elaftic fluid's, pofl"efling diftmft properties ; but as they all agree in elafticity, . 

 Xhit \s, .m their particles repelling each other by a force decteafing as their diftance, it feems ^ 

 to have been tacitly. admitted by modern phllofophers, that the fame. law. of repulfion takes 

 place between two particles of different fluids, as does between two particles of the fame 

 fluid. This admiflTion, T conceive, has been a moft unfortunate one, and liie caufe of 

 Vol. v.— October 1801. . li. much 



