36 Experiments with the Elementary Voltaic Battery. 
6. Similar experiments with another set of metals, that had also 
been used before. 
Copper and Zinc B. 
after 5’ interval. 
1. 65° 60° 
2. 62 60 
3. 60 ot 
4, 59 56 
New zinc with copper B. New copper with zinc B. 
1. 46° 1. 145° 
2. 43 2. 100 
3. 40 3. 93 
Above copper and zinc, named new. 
My 908 
2! 87 
3! 85 
From these results, we think it is clearly shown that the decline 
is to be attributed principally to the copper. Indeed, in none of our 
experiments have we observed an increase of effect from substituting 
anew zinc in place of one that has been previously used, but on the 
contrary, as above, a sensible decline. But on the other hand, when 
a new copper was introduced, there was always a great increase of 
effect. 
While engaged in these experiments, we discovered that metals 
of the same size, differed in the amount of their deflecting power, 
and accordingly we became desirous of ascertaining to what cir- 
cumstance this might be attributed. As it could not escape notice 
that there existed a diversity of surface in plates, even if taken from 
the same mass, it occurred to us to try what effect would be produ- 
ced by altering the surface mechanically, and by the action of chem- 
ical agents. ‘The results now obtained were remarkably striking, 
and show in a very interesting manner the importance which be- 
longs to the surface in the developement of Voltaic electricity. 
They also seem to teach us that the estimate which we had hereto- 
fore attached to new and clean metallic surfaces in voltaic plates 
arose from the want of a sufficiently minute attention to the circum- 
stances under which the surfaces were contemplated, as well as in 
confining our observations too exclusively to the zine. 
