metallic substances as conductors of electricity. 21 
The electrical machine employed to charge this battery 
consisted of a circular plate of glass, three feet in diameter, 
mounted between two horizontal supports of mahogany, the 
rubbers being insulated on glass pillars at each side of the 
plate, and joined together behind it by means of a curvilinear 
tube of brass, which formed the negative conductor; whilst 
the. prime conductor projected vertically from the front of the 
frame. 
The following table exhibits the results deduced from an 
extensive series of experiments on the different metallic sub¬ 
stances above-named, in which the effect of the explosion is 
placed opposite the corresponding metal. 
Metals. 
Effects. 
Metals. 
Effects. 
Copper . 
6 
Copper I part, silver i part 
6 
Silver . 
6 
Copper I part, silver 3 parts 
6 
Gold . 
9 
Copper 3 parts, silver 1 part 
6 
Zinc. 
18 
Gold I part, silver i part . . 
20 
Platinum . 
30 
-2 
Gold 1 part, silver 3 parts . 
15 
Iron .. . 
30 
C 
^ Gold 3 parts, silver i part . 
25 
Tin. 
36 
^ Tin I part, lead i part .... 
5 + 
Lead. 
72 
Tin 3 parts, lead i part. .. . 
45 
Brass .. 
18 
< 
Tin I part, lead 3 parts . .. 
63 
« r Gold I part, copper i part 
20 
xn 
( Tin I part, zinc i part .,.. 
27 
<{ Gold 3 parts, copper i part 
25 
< 
( Tin 3 parts, zinc i part ... 
32 
^ L Gold I part, copper 3 parts 
Copper 8 parts, tin i part ..., 
i8 
There are some interesting circumstances observable by 
reference to this table. If we consider the heat to be in the 
inverse ratio to the conducting power, it appears ; 1st. That 
the heats evolved from silver and copper are alike, as also 
those of iron and platinum, and likewise zinc and brass; 
whilst the heats evolved from lead and tin, compared with 
each other are as 2:1; the same may be said of zinc and 
gold, or brass and gold. 
