68 Mr. C. Binks on Electricity^ 



by continued immersion upon the zinc plate might be com- 

 pensated for by the retarded action occurring upon its asso- 

 ciated copper plate. But the rates at which the one is acce- 

 lerated and the other diminished are different, as this table 

 serves to show, and consecjuently any method of correcting 

 such irregularities of action founded upon these opposite 

 properties of the two plates would be futile. 



46. VII. The kind of polish also of the copper plate, and 

 the cleanliness of its surface, have likewise a material influence 

 upon its action, and consequently upon the results of experi- 

 ments conducted with any measure of accuracy. The plate 

 becomes soiled by frequent handling, and particles of the wax 

 from the adjacent wires are liable to be transferred to its sur- 

 face, and in the end, by their accumulation, almost .totally to 

 obstruct its further action. 



47. VIII. Again, the action of any voltaic arrangement is 

 greatly affected by the condition of the surface of the zinc 

 plate, as regards its roughness or smoothness. An irregular 

 rough surface of zinc will give a greater amount of action in 

 a given time than one which has a fine polish. 



48. IX. And, on the other hand, an exceedingly irregular 

 or rough surface of zinc, over which a profusion of mercury 

 has been spread, will exhibit a less amount of action than 

 another surface which is perfectly smooth, and over which 

 only so much mercury has adhered as has been required to 

 produce a perfect amalgam. These apparently contrary 

 effects under like circumstances are easily explained : — the 

 plate of zinc which is rough and full of cavities, on being suf- 

 fused with mercury, presents but here and there a point of 

 zinc amalgam to the action of the acid, the other parts of its 

 surface being pure mercury ; whereas, in the other case, in ' 

 which the surface is smoother and its cavities consequently of 

 less extent, a greater number of amalgamated zinc points are 

 exposed to the action of the acid, and the effect of the plate 

 is consequently greater in proportion to the evenness of its 

 surface. 



49. These different conditions of the zinc surface, however, 

 are very different in their effects if the zinc be not amalga- 

 mated; for in that case an entirely different principle of action 

 is introduced ; but as it is amalgamated zinc alone which is 

 used in these experiments, this particular need not be further 

 alluded to. 



50. X. The insoluble impurities contained in common zinc 

 accumulate upon the surface of a plate which has been long 

 used, and unless removed from time to time will also serve in 

 the end, and in addition to those causes already mentioned, 



