360 



be, the expansibility is alike in all, and that 

 they all undergo, by the addition of the same 

 quantity of fire, the same relative increase in 

 their bulk. Mr. Dalton found that 100 parta 

 of air, by having its temperature raised from 

 65 to 212, expanded 132-5 parts, which gives aft 

 increase of bulk of 000,207, or ^ parts to 1. 

 Can it, I would ask, be supposed that this won- 

 derful increase of bulk can arise from the in* 

 creased pressure of the air upon it, and that 

 the removal of resistance is the cause from 

 whence this expansive power is derived? A 

 supposition, such as this, is a most erroneous 

 one ; the abstraction of any compressing force, 

 from any expansible body, does not impart to 

 it any expansible power. The expansible 

 power of air existed before the compressing 

 force was applied ; it existed from the instant 

 that the gas was formed, and the substraction 

 of the compressing force, has the effect only of 

 enabling the expansible body to expand with 

 greater freedom than before.* 



* 1 hope to be excused from reverting again to this sub- 

 ject. If any quantity of gas be made under water, the surface 

 of which is not an inch above the vessel in which the gas is 

 received, the gas will possess the same degrees of expansible 

 power, as if it were made in the open air. It will, I know, 

 be said, that the whole incumbent weight of thfe atmosphere 

 still exists. I allow that the atmosphere exists, but I deny it 

 exerts the weight which is ascribed to it. I appeal to the 



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