TRANSACTIONS OF THE SECTIONS.. 185 
In the case of electricity, however, there is no analogous difficulty, but we have 
instead the difficulty and expense of developing current electricity by the chemical 
actions now requisite. . If carbon could be burnt or oxidized by the air, directly or 
indirectly, so as to produce electricity instead of heat, 1 pound of it would go as far 
as 94 pounds of zinc (in a Daniell’s battery), chiefly because there are as many atoms 
in 1 pound of carbon as there are in 53 pounds of zinc, and partly because the affi- 
nity (for oxygen) of each atom of (incandescent) carbon is greater than that of an 
atom of (cold) zinc, minus the affinity of the hydrogen for the oxygen in the water 
of the battery. Apart, however, from such prospects of improved means of obtain- 
ing electricity, its favourable feature, on the other hand, in comparison with heat, is 
the reasonable expectation that we may obtain from electricity a considerable portion 
of the power which the author has determined as being the dynamic equivalent of 
the electric current. 
Table of the Relative and Absolute Powers of Galvanic Arrangements, 
showing the electric current circulated, after the surfaces of the elements 
have been in continued action for several hours, with continuous supplies of 
liquids, the temperature being 70°. By Wit.1aM PETRIE. 
Column headed Surface for Quantity shows the square inches of acting negative 
surface requisite to circulate one unit of quantity. 
Column headed Intensity shows the permanent electromotive force of the elements 
while in action. 
Surface Hider 
Description of the Electromotor. for si ϊ ᾿ 
Quantity. ys 
Double fluid batteries. 
{ Hard cast iron with nitric acid, and zinc with 4 100 
dilute sulphuric acid; warm, say 80°...... Ξ 
| Grove’s .... Platinum with nitric acid; and ditto. ........ 42 | 102 
Carbon with nitric acid (80° femp.); and un- 
The author’s amalgamated zinc, with a saline solution 42 |112 
(ORME PALENE) wince tern late landis aisle sacs Gait cioness « 
ana Copper with sulphate of copper, and amalga- 
Daniell’s. . . { mated zinc, with dilute sulphuric acid .... } 16 60 
Single fluid batteries. 
5 Platinized silver and dilute sulphuric acid, and 
Smee’s .... { amalgamated zinc.,......... Parone sarge eye 53 36 
—_-—- Plain copper, with amalgamated zinc.......... 52 18 
Plain lead, with amalgamated zinc...... Aces 104 235 
Thermo-electric pairs, bars of bismuth and an- } | section of 
Melloni’s .. timony, 1 inch long, difference of tem perature > leach metal = 
OL (HELE ἘΠΟΒ ΟΣ ὉΠ on 0 fs etna wie ct fe 2 sq. in. 
SS SS ee a a a a ges . 
The intensity of all the single fluid batteries is variable, except that of lead, which 
is remarkably constant though low (18°). That of Smee’s is very variable, from 55° 
to 25° or lower, the cause of which the author explained to the Association. 
These data have been found very useful in determining the best proportions and 
qualities of batteries for practical purposes. 
On the Dynamie Equivalent of Current Electricity, and on a fixed Scale for 
Electromotive Force in Galvanometry. By Wit11AM Pettis. 
The dynamic value of a current of voltaic electricity is represented by the product 
of the rate at which electro-chemical action is taking place at any cross section of 
