8S-± Mr. Wilson Taylor on the Coalescence of 



possess potential energy and consequently are affected by 

 surface tension. 



Hence, if we take L = 498, which is the average of the 

 values given in the tables corrected for external work 

 amounting to 41 calories, 



pQ — p277 z= l) m = 18, and T wl =133'6, 

 the formula, 



gives by calculation 



n = 6*05xl0 23 . 



Millikan's value for this number, obtained by his balanced 

 drop method, is 6 0o5 x 10 23 ; while Perrin's value, obtained 

 by studying the motion of a colloidal sphere in water, is 

 6'86 Xl0 23 . 



The result obtained above would seem to furnish an argu- 

 ment in favour of the view that the properties of surface 

 tension can be considered as not depending upon the mutual 

 attraction of molecules. For, if the free molecule has about 

 it this elastic envelope, it is plain that the envelope cannot 

 be material at all. It is simply a force and nothing more. 



Since the force of gravity in its relation to potential 



energy is denoted by -=— , where x is the distance between 

 ° " ax 



the centres of the masses attracting each other, this force 



will be denoted by — , where A is the area of the mass 



about which it acts. Also, because of the curvature of this 

 area the force acts to compress the interior of the sphere to 

 a smaller volume ; but the action is prevented by anoth< r 

 force in the interior which mast, therefore, be denoted b\ 



— y } where Y is the volume within the enveloping force. 



It may be that all physical phenomena may be explained in 

 terms of these three fundamental physical forces, of which 

 beyond these distinguishing characteristics we know but 

 little. What these forces are per se we have no^idea. 



The formula obtained above appears to hold for all 

 spherical masses of liquids, whatever be their size. For, 

 since it gives a value of N practically identical with those 

 we already know, it suggests that the law of coalescence of 

 water spheres does not break down at any point from the 



