Experiments with the Elementary Voltaic Battery. 37 
7. The first experiments on what we may conventionally call the 
character of surface, were made with two zinc plates, which had 
been previously used. 
Zinc No. 1. 85° permanent deflection. 
74 66 2, 84 (<9 c¢ 
The surface of zinc No. 1. after being filed and brightly polished, 
gave 75° repeated 74° permanent deflection. 
Zinc No. 2. after exposure 2’, to the action of a strong solution 
of sulphuric acid and water, gave 
85° repeated 78° 
It appears from these and other observations, which we have 
thought it unnecsssary to detail, that the deflectory power of the 
zinc is but little altered by changing the character of surface. 
But the most interesting observations connected with this part of 
our subject, have relation to the changes induced in the copper sur- 
face. These we deem it proper to detail somewhat in extenso, for 
if corroborated by other experimenters, they are likely to exert an 
important influence upon the practical as well as theoretical consid- 
erations of voltaic electricity. 
8. In the following experiments, we varied the relative propor- 
tions of zinc and copper so as to keep constantly in view the impor- 
tant point which engaged our attention in the commencement of this 
paper, viz. the greater importance which belonged to an increase of 
copper over asimilar increase of zinc surface. 
On character of surface. Copper constant at 3 sq. inches. 
zinc 2 in. zinc 4 in. 
No. 1 copper, 2 60° 2/ 58° 
af 1CA"58 Be Pan 
Die a zZ. 4. 
No: 2 copper;’ 2/ 55° ay Ne 
3! 53 3/ 70 
No. 1 copper was now immersed 5/ in a hot solution of nitric 
acid and water, and allowed 8’ exposure, without wiping, and gave 
“MTEL LION 7, 2°10 z. 4 in. Ze Qin. Zz. 4 in. 
Diet 771° A109 ola a ee 200° 
Gina Fee 208 ST ay isl Fel 190 
Ain 15 206 «fj A’ 176 190 
No 2 copper, immersed in a boiling solution of muriatic acid and 
water 5/ and allowed 8’ exposure without wiping, gave 
