Then trace a cross on the electrophorus bed with the knob, making the cross inside of the circle.
Fig. 51.—Lichtenberg's Figures.
Shake a mixture of red lead and sulphur through a muslin bag from a height of several inches over the electrophorus.
The red lead will accumulate around the cross and the sulphur around the circle.
CHAPTER IV CELLS AND BATTERIES
In order that the young experimenter may obtain electricity for driving his various electrical devices it is necessary to resort to batteries, a small dynamo, or the house-lighting current.
All houses are not supplied with electric current. Furthermore, many boys have no source of power from which to drive a small dynamo. Batteries must therefore be resorted to in the majority of cases.
A number of different cells and batteries are described in this chapter. All of them are practical, but after buying zinc, chemicals, etc., for any length of time, figure out what your batteries cost you to make. The real value is not their cost in dollars and cents but in what you have learned in making them. If you have a continuous use for electrical current for running small electrical devices it is cheaper to buy dry cells, or what is better, a storage battery, and have it recharged when necessary.