Voltaic BatterieSf 8fc. 55 



ment, whether simple or compound, whose elements were 

 zinc, copper, and dilute sulphuric acid, appeared to be placed 

 in the best circumstances for the exercise of its full power 

 when under either of these two conditions ; — first, when the 

 extent of the copper surface was sixteen times greater than 

 that of the zinc ; or, secondly, when the surface of the zinc was 

 made the greater of the two in the proportion of about seven 

 to one of copper. 



3. To state these results more definitely, let the zinc plate 

 first used have an area, on each surface, of one square inch, 

 and let its associated copper plate be of the same size. The 

 voltaic action resulting from this arrangement being ascer- 

 tained and taken as unity, and as a standard of comparison, let 

 the zinc and all other conditions remain as at first, but let the 

 copper plate be displaced by others, successively, whose areas 

 increase in a regular progression ; when it will be found that 

 with a copper plate of two square inches on each surface, or 

 twice the size of the first, the action will be equal to 1*3; 

 with one of four square inches, equal to \'Q\ and so on, by a 

 certain progressive rate of increase till we reach to an area of 

 16 square inches, when the action will be found to have ar- 

 rived at its maximum, and to be, in numbers, equal to 4*6. 



4. Beyond this point the action will be augmented by no 

 further addition whatever to the size of the copper plate ; but, 

 on the contrary, such further additions cause as remarkable a 

 progressive decrease. 



5. And, on the other hand, when we retain the copper 

 plate of one square inch first used, but substitute for the small 

 zinc one others of zinc in succession, progressively larger, a 

 corresponding progressive increase of action will likewise fol- 

 low till the zinc plate becomes of an area of about 7 square 

 inches, at which point the greatest amount of voltaic action 

 will be obtained, being in numbers equal to about 3 compared 

 with the standard amount of 1 ; and this amount will suffer 

 neither increase nor diminution by any subsequent addition 

 whatever to the dimensions of the zinc plate. 



6. The relative proportions of the two plates at which the 

 maximum effect took place as thus determined, were obtained 

 when both surfaces of the zinc, as well as both surfaces of the 

 copper plate, were exposed to the action of the exciting acid ; 

 thus making, in the case in which the copper is the larger, a 

 total area of 2 square inches of the zinc and 32 square inches 

 of the copper, and constituting a ratio of 1 to 16. 



7. But subsequent experiment (see section 8th) has deter- 

 mined that this same extent of copper surface is needed as 

 well when only one, as when both surfaces of the zinc are 



