d the Westo?i Normal Cell. 



253 



other limbs; in the remaining limb, mercury and a depolarizer 

 consisting of a paste of mercurous sulphate and cadmium 



Fiff. 1. 



r^\ 



r\ r 



/ v 



u 



1 



sulphate crystals and solution were introduced. Cadmium 

 sulphate crystals were added so as to form a deep layer over 

 the amalgams and paste, and afterwards the vessel was nearly 

 filled with a neutral saturated solution of cadmium sulphate. 

 The vessel was then hermetically sealed. 



Such a cell will be seen to consist of one positive element 

 and three negative ones, one of which consists of a 10 per 



1. amalgam. 



The advantages of such a cell are : — 



(1) All of the constituents of the Weston normal cell are 



present. 



(2) The electromotive force of any combination having the 



mercury as the positive element and one of the 

 amalgams as the negative element, may be directly 

 compared with the electromotive force of any 

 standard cell. 



