IsATTERLY] SURFACE TENSION, ETC. 91 



ciently known to make it worth while bothering with the method as 

 a means of calculating Avogadro's number. 



Again using his formulae for the potential surface energy Taylor 

 deduces that if d is the diameter of a molecule 



\tvpN/ 

 but this can be obtained more simply from the mass equation 



(f)- 



N l"!^ 



m 



without bringing in surface tension at all. 



I find it difîhcult to follow Taylor's reasoning when he says: 



"The result obtained above (i.e. the deduction of iV= 6.05X10-^) 

 would seem to furnish an argument in favour of the view that the 

 properties of surface tension can be considered as not depending 

 upon the mutual attractions 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." 



Again, in Nature, Jan. 5, 1922, he says that the coalescence of 

 gaseous and liquid spheres is not due to molecular attraction. "The 

 alternative is that it is an elemental force acting, not in lines, but 

 over areas." 



Also in the Physical Review, April, 1922, he says "Cohesion 

 and adhesion are simply surface tension forces which exist about 

 all free masses, molecular or larger, attaching themselves to each 

 other in the periphery of the contact area and binding the two masses 

 together in one enveloping surface tension force." 



The connection between forces and binding envelopes is vague, 

 and forces acting not in lines are beyond my comprehension. 



It is interesting to see how nearly 5' remains constant as the 

 temperature is changed. From 



dd 

 dT _ dS dT d-T 



Id ~ dd ^ do ~^ ^ dd- 

 , dS d^T 



" dd^~^ dd' 



dT . d-'T 



If ~ is constant -777 =0 and .'. 5 does not vary with temperature. 

 du do'' 



