418 On the Theory of Mixed Gases, 



to create any doubt or misconception ; in the 

 present instance, however, he accuses several 

 of his readers of misunderstanding his fourth 

 proposition ; and the nature of the mistake is 

 clearly stated in the foregoing quotation. My 

 essay will shew, that the charge does not reach 

 me y because the impossibility of two gases 

 mixing instantaneously is demonstrated, imme- 

 diately preceding the refutation of that pro- 

 position. 



Thus much may be said in relation to the 

 notion of gaseous flu ids penetrating each other : — 

 As for the application of ,the general idea to the 

 particular case of vapour, Mr. Dalton^s readers 

 have an indisputable right to vindicate their 

 understandings, by quoting such passages of 

 his essays as they may think proper : the passage 

 alluded to in particular by me, is this. *' The 

 •' obstruction, however, cannot arise from 

 *^! the weight of the atmosphere, as has till now 

 ** been supposed ; for then it would effectually 

 •* prevent any vapour from arising under 212°; 

 •' but it is caused by the vis iriertiw of the par- 

 ** tides of air ; and is similar to that which a 

 •* stream of water meets with in descending 

 " amongst pebbles."* 



The preceding illustration of the passage of 



« Manchester Memoirs, Vol. 5. p. 580. 



