and on the Construction of Voltaic Batteries, 87 



what proportions should be observed between the two metals 

 when the copper is immersed in a solution of its sulphate. 



The experiments were conducted as in the first investiga- 

 tion. The zinc was immersed in dilute sulphuric acid, formed 

 of 4| acid to 100 water, and confined in a membranous bag, 

 the copper solution surrounding it. 



The zinc plate measured 2 square inches ; it, as well as the 

 acid and solution, was renewed each time of immersion. The 

 first copper plate was equal in size to the zinc, then the copper 

 plates were used of larger sizes in succession, as seen in the 

 table. 



Table No. 14. 

 1st, zinc with copper, equal, in 30 minutes lost... 6*0 grains 



2nd, twice its size do. lost... 7*0 — 



3rd, 4 times do. do. lost... 9*0 — 



4th, — | 8 times do. do. lost... 13*3 — 



5th, 16 times do. do. lost... 11*5 — 



6th, 20 times do. do. lost... 10*0 — 



I am wholly unable to account for the deficiency in action 

 observed in the fifth and sixth instances, when compared with 

 the fourth, since the conditions of the experiments were in 

 each instance precisely alike, save of course the size of the 

 experimental copper plates. 



This table, therefore, indicates that it is when the copper 

 plate is about eight times larger than the zinc one, that the 

 greatest effect ensues in the case in which sulphate of copper 

 surrounds the conducting plate, and the voltaic action is ac- 

 companied by the deposition of metallic copper and the refor- 

 mation of water. 



These trials were varied twice ; first by using a stronger 

 acid solution to act upon the zinc ; and secondly, by using 

 merely water for the same purpose, when the results exhibited 

 the operation of the same law, namely, that the maximum ef- 

 fect followed upon the employment of the copper plate about 

 eight times larger than the zinc. 



For reasons already sufficiently adverted to, I have con- 

 fined my examinations to some of the cases most commonly 

 met with in the ordinary employment of the battery. But 

 were this kind of examination extended into every case of 

 voltaic action in which different bodies, that is, bodies physic- 

 ally different from one another, are the result of the opera- 

 tions within the cells of the battery, I have no doubt that a 

 specific and different proportion between the sizes of the two 

 constituent metals would be found to be needed for each case, 

 in order to obtain the maximum effect ; and that the relations 

 which would be thus discovered would be at once curious 



