KINETIC THEORY OF GASES 



cease then to be a gas, but would become liquid or 

 solid ; or the effect of gravitation upon the diffused 

 molecules may overcome their dispersive motion, which 

 may be inherent in themselves or more probably be 

 caused by contact with the ever-moving ether atoms. 

 It should be noticed that the normal pressure ; that 

 is, the actual weight of nearly fifteen pounds per 

 square inch of the aerial molecules of the atmosphere 

 pressing upon our bodies, is absolutely outside of and 

 beyond our consciousness, even though the molecules, 

 independent of their pressure, actually are striking 

 us with the velocity of nearly 1500 feet per second. 

 The pressure is uniform inside and outside through- 

 out our frame, and, being alike in all directions, is 

 unfelt by us. It is only when the pressure is with- 

 drawn from one side of our hand or other portion of 

 our body, by means of removing the air with an air- 

 pump or other similar device, that we can realize that 

 the weight or pressure of upwards of 30,000 to 40,000 

 pounds is actually distributed over our body. 



In all such objective phenomena the testimony of 

 our senses is fallacious. The revolution of the earth 

 on its axis, when first announced, seemed opposed to 

 our common sense, was absurd and heretical. Lord 

 Bacon so considered it. The lapse of time has recon- 

 ciled us to the thought, and it has ceased to seem 

 strange to us; yet each true new theory goes to some ex- 



