364 Mr. Children’s experiments 
considerably increased the power of the battery. From some 
comparative experiments, which I made with a small appa- 
ratus, the increase in quantity of electricity, thus effected, is 
at least one half. The cells of the battery are 21 in number, 
and their united capacities amount to 945 gallons. To each 
pole of the battery a leaden pipe, about •fths of an inch in 
diameter, is attached by solder, and the opposite end of each 
pipe immersed in a basin of mercury, ( a separate basin for 
each pipe), by means of which the circuit is compleated, and 
a perfect contact ensured. The first experiments I shall men- 
tion were made on the comparative facility with which dif- 
ferent metals are ignited when placed in the electrical circuit. 
For this purpose, in each experiment, two wires of dissimilar 
metals were taken, of equal diameter and length ; one end of 
each was in contact with one of the basins of mercury com- 
municating with the poles of the battery, and the other end 
bent to an angle, and the wires connected continuously by 
hooking them together. The length of each wire was 8 
inches, and the diameter ~th of an inch. The battery was 
moderately excited by a charge of 1 part acid diluted with 40 
parts of water. 
Exp. 1 . A platina and a gold wire being thus connected, 
and introduced into the electrical circuit, the platina was 
instantly ignited, the gold remained unaffected. 
Exp. 2. A similar arrangement of gold and silver wires. 
The gold was ignited, the silver not. 
Exp. 3. The same with gold and copper. No perceptible 
difference in the state of ignition ; both metals were heated red. 
Exp. 4. Gold and iron. The iron was ignited ; the gold 
unchanged. 
