CHEMICAL HISTORY OP A CANDLE 153 



afterward exhausted] you see what happens. Why is my 

 hand fastened to this place, and why am I able to pull this 



FIG. 8 1 



pump about ? And see ! how is it that I can hardly get my 

 hand away? Why is this? It is the weight of the air 

 the weight of the air that is above. I have another experi- 

 ment here, which I think will explain to you more about it. 

 When the air is pumped from underneath the bladder which 

 is stretched over this glass, you will see the effect in another 

 shape : the top is quite flat at present, but I will make a very 

 little motion with the pump, and now look at it ; see how it 

 has gone down; see how it is bent in; you will see the 

 bladder go in more and more, until, at last, I expect it will 

 be driven in and broken by the force 

 of the atmosphere pressing upon it 

 [the bladder, at last, broke with a 

 loud report]. Now that was done 

 entirely by the weight of the air 

 pressing on it, and you can easily 

 understand how that is. The par- 

 ticles that are piled up in the at- 

 mosphere stand upon each other, as 

 these five cubes do; you can easily 

 conceive that four of these five cubes 

 are resting upon the bottom one, and 

 if I take that away the others will 

 all sink down. So it is with the "* ' FlG g2 

 atmosphere; the air that is above is 

 sustained by the air that is beneath, and when the air is 

 pumped away from beneath them, the change occurs which 

 you saw when I placed my hand on the air-pump, and which 



