Mr Kemp on a New Kind of Galvanic Pile. 71 



doubt, prevented, in some measure, the various interesting 

 phenomena which galvanism presents, the laws which govern 

 its action, and its connection with magnetism and electricity, 

 from being more fully investigated. 



In performing many of the more important experiments in 

 the science, different sets of batteries are necessary, according as 

 the substances to be acted upon are more or less perfect con- 

 ductors ; and the cost of these batteries being very considerable, 

 few private individuals are possessed of an apparatus sufficiently 

 varied, for investigating the different branches of the subject. 



Independendy, however, of the expence in procuring the re- 

 quisite apparatus, another point is to be taken into considera- 

 tion, and that of the utmost importance, viz. the rapidity with 

 which zinc plates become oxidated, rendering them completely 

 useless for exciting the galvanic fluid, before the batteries are 

 lialf worn oul ; and even in conducting experiments where much 

 time is required for observing the results, the quantity of oxide 

 formed on the surface of the zinc plates first retards the action, 

 and finally prevents the motion of the fluid. 



A battery, therefore, which might beprocured at little expence, 

 (the principal material being in the possession of every chemist), 

 where little or almost no oxide is formed on the surface of the 

 metal, and where the action is much more continuous, would be 

 a very great desideratum, to supply which is the intention of the 

 following paper. 



It had frequently occurred to me that mercury might be used 

 as one of the metals for forming galvanic apparatus ; and, from 

 the difficulty with which it is acted upon by most of the acids, 

 would answer the purpose of a negative metal better than any 

 other, gold and platinum excepted ; unless, indeed, its fluidity 

 destroyed the capability it otherwise possessed for exciting gal- 

 vanic energy. 



After several attempts to obviate this seeming difficulty, I at 

 last succeeded in producing the following apparatus : 



AB, CD, Fig. 1. Plate II. represents a circular wooden cup, about half an 

 inch deep, and about three inches in diameter, having a projecting rim AB. 

 EF is a circular convex plate of zinc, attached to the cup, and about an eighth 

 of an inch from it, by a wire either of copper or zinc, the extremity of which 

 passes through, and projects within, the bottom of the cup, about the one- 



