Mr. Dalton on the constitution of the atmosphere, 183 



The arguments in support of this notion may be derived 

 from the following facts : 



1st. When two gases, not having a manifest chemical 

 action upon each other, are put into a vessel of small limited 

 capacity, they are found in a short time to be uniformly 

 diffused through the capacity of the vessel, whatever be their 

 proportions. 



2d. Let a bottle, having its air exhausted, be half filled 

 with water, and the other half with a mixture of equal 

 volumes of two gases, suppose hydrogen and carbonic acid ; 

 then let an air-tight stopper be applied, and the contents of 

 the bottle be duly agitated. The carbonic acid will be found 

 equally diffused through the whole capacity of the bottle, the 

 same in the water as out of it ; but the hydrogen in the 

 water will only be ■— or /^ of the density of that above 

 the water. In this case each gas will be arranged, both 

 within and without the water, precisely the same as if it was 

 the only gas present. And if a third gas could afterwards 

 be introduced into the bottle in hke manner, it would take 

 its place in and out of the water independently of the other 

 two ; and so on with any number. No pressure of any one 

 gas on the surface of the water can confine another gas in 

 the water ; it must be a pressure arising from the same gas. 



3d. If a portion of ether, alcohol, &c. be put into a bottle, 

 and it be close corked, the vapour will ascend and fill the 

 bottle, whatever air be present ; its quantity and force will 

 be the same whether there be any air, or none, being entirely 

 regulated by the temperature. 



From these three facts, but more especially from the two 

 last, it appears to me as completely demonstrated as any 



