ON THE CONSTITUTION OF MIXED GASES, ifC, 257 



6n the firfl opportunity, and fliall then either confirm or 

 modify in a future notice, as my own obfervation fliall dire6l, 

 thefe particulars of information, which upon good grounds I 

 have thought myfelf juftified in now laying before my readers. 



W. N. 



XIII. 



Experimental EJfays on the Confiitutlon of mixed Gafes; on the 

 Force of Steam or Vapour fro?n Water and other Liquids in 

 different Temperatures, both in ti Torricellian Vacuum and in 

 Air ; on Evaporation ; and on the Expanfion of Gdfes by Heat. 

 By John Dalton *. 



Jl HE progrefs of philofophical knowledge is advanced by The difcovery 

 the difcovery of new and important facts; but much n^ore is o^f high vTue 

 when thofe fafts lead to the eftablirtiment of general laws. It in the advance- 

 is of importance to underftand tliat the defcent of falling "'<^'^'°^^'=''"" 

 bodies is the fame every where on the furface of the earth; 

 bat from that and forae other particular fads to infer the law 

 of gravitation, or that all matter attracts with a force decreaf- 

 ing as the fquare of the diftance, is a much higher attainment 

 in fcience. In the train of experiments lately engaging my 

 attention fome new fads have been afcertained, which with 

 others, feem to authorize the dedudion of general laws., and 

 fuch as will have influence in various departments of natural 

 philofophy and chemiftry. 



* Thefe interefting treatifes were read before the literary and 

 philofophical Society at Mancbefter, in 0£tober, 1801, and are 

 piibliihed in the fifth volume of their memoirs. The firft, on mixed 

 gafes, was communicated in the fame month, in a fomewhat different 

 form, by the author to our Journal, and publifhed in the quarto 

 feries, vol. V. p. 241. — -and, a further communication from him 

 oil thefr^me fubjeft appeared in Vol. HI. p. 267 of our prefent feries. 

 I have not, thsrefore, reprinted that eflay of the prefent colleftion. 

 The laft effhy in the title, viz. on the expanfion of gafts, isinferted 

 in the laft mentioned volume, p. 130. — Coiifequently though the 

 title and introduftion refer to thev/aole four; yet the prefent article 

 contains only what was wanting to complete the readers poffeilion 

 of this valuable mafs of experimental knowledge j that is to fay, 

 the effays upon fleam and upon evaporation. 



Vol.. VI.— December, 1803. S A« 



