OF ENERGY IN A SYSTEM OP MATERIAL POINTS. 741 



In order to obtain a similar distribution of the two gases in a vertical 

 tube by the action of gravity the tube would require to be 1720 metres high, 

 and in order to obtain the same degree of approximation to the ultimate 

 distribution we should have to let the experiment go on for 675 years, 

 carefully preserving the tube during that time from all inequalities of tempera- 

 ture, which, by causing convection-currents, would continually mix up the gases 

 and prevent their partial separation. 



