ON THE ENERGY OF STORMS — -MARGULES 579 



In the case of motion without friction we have for air 



(V) = V 2 C V T (1 - 2-°- 41 ) = 0.7034 V C V T. 



For the temperature T = 273 this equation gives (V) = ^ojm./sec. 

 If we assume that the kinetic energy is confined to that half oi 

 the mass that flows out of the first chamber into the second, we 

 find the velocity 435 m./sec. These values are of the same magni- 

 tude as the molecular velocities. In small vessels the kinetic 

 energy is very soon converted (by friction) into heat and is added 

 to the internal energy of the system This added heat that we 

 fail to notice in our atmospheric movements is decisive for the 

 result of the laboratory experiment. Probably the experiment of 

 Joule would have given a very different conclusion if he could have 

 performed it in vessels of very large horizontal extent. In that 

 case one should have observed a diminution of the internal energy 

 at whose cost arose the kinetic energy of the systematic motion 

 appropriate to the extent of the vessel. The previous portion of 

 this article has been suggested by the relation of our problem to 

 Joule's experiment but the following suggestion which has perhaps 

 already been made elsewhere may be added. In the case when the 

 volumes of the gas chamber and the vacuum chamber are unequal 

 and with the assumptions that the motion is frictionless and that 

 the change of condition is adiabatic and that at certain moments 

 the pressure p' is uniform throughout the whole space, we have 



*■ p ' 



M (V) 2 

 -dl= { } = MC V T 



k 



If the vacuum chamber is very large relatively to the gas chamber 

 so that k 1 /k = approximately and since 7-— i>o therefore this 

 equation gives 



On the other hand, from the kinetic theory of gases, if (u 2 ) is the 

 mean of the squares of the velocities of the molecules of gas in the 

 non-systematic free motions of molecules [or (w 2 ) is the square of 

 the mean free path] we have 



1 3 



