50 



LIBERATION OF ENERGY 



Capillary Electrometer. — Lippmaii made use of the electrical 

 alteration of surface tension in his capillary electrometer which 



M 



(A) 



(B) 



Fig. 12.— Diasraui of Capillary Electrometor (Crocker and Matthews). 

 12A.—T. the reservoir of mercury containing the insulated electrode E, communicates by t/ 

 with the caiiillarv A. Above the mercury in A. and tilling the upper part of B, is dilute 

 sulphuric acid. F, the other electrode, passes into the mercury at the bottom ot -o and 

 F is kept out of contact with the acid. When not in use F and E are short circuited 

 by a key. 

 B represents the surface of the mercury M in contact with the acid S. 



consists essentially of a capillary tube containing mercury and 

 dipping into dilute sulphuric acid (Part II., p. 520 and Fig., 12). 

 The mercury contains one leading in wire from a source of potential 

 difference, while the other lead is taken to a small amount of 



