﻿430 Photographic Measurements of Pendent Drops* 

 redaction 



T f 2.v 



coj 



8 



where tan 



dy_ 



in £-5 J = ^gpxy 2 , 



This equation affords a means for 



estimating T by measurements made on the drop alone, a 

 method which may prove useful in certain cases (e. g. a 

 pendent drop of a molten metal) where it is experimentally 

 impracticable to make measurements of h. It is to be re- 

 membered, however, that the coefficient of T is small, and is 

 obtained as a difference, so that reliable results would 

 require somewhat close measurement and a high percentage 

 accuracy in the experimental observations. 



To sum up. The above results would seem to point to the 

 following conclusions : — 



(1) Over a definite portion of the drop near the vertex, 

 the outline may be represented by a parabolic or biquadratic 

 equation. 



(2) The constants of this equation can be readily deter- 

 mined, thns allowing of an evaluation of the surface-tension 

 independently of any knowledge of the angle of contact. 



(3) [By forming the pendent 

 drop in a rectangular glass tank 

 or cell filled with [mother fluid, 

 inter facial tensions can be mea- 

 sured in a similar manner. 



(4) By turning up the end of 

 the siphon-tube in the manner 

 shown, the phenomena attendant 

 on the formation of sessile drops 

 can be similarly studied. 



(5) Granted sufficient ex- 

 perimental accuracy, determina- 

 tions of T can be made from 

 measurements carried out on the 

 drop alone. 



The writer trusts, in a subsequent communication, to 

 detail results dealing with the aboye points. 



University College of Xortli Wales. 

 Bangor. 



Oct., 1911. 



