Demonstrations. - Hold a warm, dry glass rod over a handful of cork filings, pith balls, bits of paper, etc., and the rod will not affect them. Rub the rod briskly a few times with a piece of silk or flannel, and the light bodies will begin at once to fly to the rod, will remain there for an instant, and will then fly back to the table.
by a book at each end. No effect will be noticed until the glass is rubbed with the silk, when the bits of paper will at once begin to jump to the glass and back again.
Using a flannel pad for a rubber, repeat the first demonstration with (1) a stick of sealing wax, (2) a rod of ebonite, and (3) a hard rubber comb.
FIG.1
The above demonstrations show that when glass is rubbed with silk, or sealing wax with flannel, there is imparted the property of attracting light bodies. The first record of such a phenomenon was made by the Greeks about 600 B.C. Because they noticed it in amber, which they called elektron, the name electricity has been given to the cause of these phenomena, and a body that is capable of attracting others in this way is said to be electrified.
Demonstration. - Make a wire stirrup, as in Fig. 2 and suspend in it a wooden rod two or three feet long. Suspend this by a silk thread from a support and present, near one end, an electrified glass rod. The wooden rod will be at once attracted. Take out the wooden rod, suspend the glass rod, and present the end of the wooden rod; and now the glass rod moves. Suspend both rods, and they move toward each other until they touch.
This shows that the action that takes place between an electrified and an unelectrified body is mutual.
