Continuity 41 



One very valid excuse for this preva- 

 lent attitude is the astonishing progress 

 that has been made in actually seeing or 

 almost seeing the molecules, and study- 

 ing their arrangement and distribution. 



The laws of gases have been found to 

 apply to emulsions and to fine powders in 

 suspension, of which the Brownian move- 

 ment has long been known. This move- 

 ment is caused by the orthodox molecular 

 bombardment, and its average amplitude 

 exactly represents the theoretical mean 

 free path calculated from the "molecular 

 weight" of the relatively gigantic particles. 

 The behaviour of these microscopically 

 visible masses corresponds closely and 

 quantitatively with what could be pre- 

 dicted for them as fearfully heavy atoms, 

 on the kinetic theory of gases; they may 

 indeed be said to constitute a gas with a 

 gram-molecule as high as 200,000 tons; 

 and, what is rather important as well as 

 interesting, they tend visibly to verify 

 the law of equipartition of energy even 

 in so extreme a case, when that law 

 is properly stated and applied. 



