On an improved Form of the Voltaic Battery. 115 
tion when the extremities are in communication; and in the 
perfect one, which I have described (1001.), ad/ the chemical 
power circulates and becomes electricity. By referring to the 
quantity of zinc dissolved from the plates (865.* 1126.), and 
the quantity of decomposition effected in the volta-electrometer 
(711. 1126.) or elsewhere, the proportions of the local and 
transferred actions under any particular circumstances can be 
ascertained, and the efficacy of the voltaic arrangement, or the 
waste of chemical power at its zinc plates, be accurately deter- 
mined. 
1121. Ifa voltaic battery were constructed of zine and pla- 
tina, the latter metal surrounding the former, as in the double 
copper arrangement, and the whole being excited by dilute 
sulphuric acid, then no insulating divisions of glass, porcelain, 
or air would be required between the contiguous platina sur- 
faces ; and, provided these did not touch metallically, the same 
acid which, being between the zinc and platina, would excite 
the battery into powerful action, would, between the two sur- 
faces of platina, produce no discharge of the electricity, nor 
cause any diminution of the power of the trough. ‘This is a 
necessary consequence of the resistance to the passage of the 
current which I have shown occurs at the place of decompo- 
sition (1007. 1011.); for that resistance is fully able to stop the 
current, and therefore act as insulation to the electricity of the 
contiguous plates, in as much as the current which tends to pass 
between them never has a higher intensity than that due to the 
action of a single pair. 
1122. If the metal surrounding the zinc be copper (1045.), 
and if the acid be nitrosulphuric acid (1020.), then a slight 
discharge between the two contiguous coppers does take place, 
provided there be no other channel open by which the forces 
may circulate: but when such a channel is permitted, the re- 
turn discharge of which I speak is exceedingly diminished, in 
accordance with the principles laid down in the eighth series of 
these Researches. 
1123. Guided by these principles I was led to the construc- 
tion of a voltaic trough, in which the coppers, passing round 
both surfaces of the zincs, as in Wollaston’s construction, 
should not be separated from each other except by an inter- 
vening thickness of paper, or in some other way, so as to pre- 
vent metallic contact, and should thus constitute an instrument 
compact, powerful, economical, and easy of use. On examin- 
ing, however, what had been done before, I found that the 
(* The paragraphs referred to from 661 to 874 will be found in Mr. Fa- 
raday’s Seventh Series, reprinted in Lond. and Edinb. Phil. Mag., vol. y. 
p- 161, et seq.—En1r. | 
