MR. DE LA RUE'S BATTERY. 95 



silver and a rod of zinc. At one end of the silver D is a cylinder of 

 chloride of silver cast upon it. In order to prevent contact between 

 the rods of zinc and chloride of silver, the chloride of silver is 

 surrounded with a cylinder A, open at the top and bottom, made of 

 vegetable parchment. B shows the rod of chloride of silver surrounded 

 by the cylinder. 



Figure I. 



Ag.CL 



The cell is a glass tube ; the stopper is a cork, made of paraffin, 

 and a rod of non-amalgamated zinc is inserted through a hole in it ; 

 and then there is a second aperture, closed with a small paraffin 

 plug, to enable one to fill the tube with a solution of twenty-three 

 grammes of chloride of ammonium to one litre of water. I could 

 not send the whole of my battery here ; first of all, it is not easily 

 conveyed ; and, in the next place, it would be difficult to show its 

 effects without special preparation ; but I can show you one of this 



