Page:Popular Science Monthly Volume 9.djvu/180

160 Place an egg, E, Fig. 11, on its side upon a dry wineglass; bring your excited glass tube, G, within an inch or so of the end of the egg. What is the condition of the egg? Its electricity is decomposed; the negative covering the end a adjacent to the tube, the positive covering the other end b. Remove the glass tube: what occurs? The two electricities flow together and neutrality is restored. Prove this neutrality. Neither a carrier touching the egg, nor the egg itself, has any power to affect your electroscope, or to attract a lath balanced in the manner already described.

Again, bring the excited tube near the egg. Touch its distant part b with your carrier. The carrier now attracts the straw or the balanced lath. It also causes the leaves of your electroscope to diverge. What is the quality of the electricity? It repels and is repelled by rubbed glass; the electricity at b is, therefore, positive. Discharge the carrier by touching it, and bring it into contact with the end a of the egg nearest to the glass tube. The electricity you take away repels and is repelled by gutta-percha. It is, therefore, negative. Test the quality, also, by the electroscope.

While the tube G is near the egg touch the end b with your finger; now try to charge the carrier by touching b: you cannot do so—the positive electricity has disappeared. Has the negative disappeared also. No. Remove the glass tube, and once more touch the egg at b with the carrier. It is charged, not with positive, but with negative electricity. Clearly understand this experiment. The neutral electricity of the egg is first decomposed into negative and positive; the former attracted, the latter repelled by the excited glass. The repelled electricity is free to escape, and it has escaped on your



touching the egg with your finger. But the attracted electricity cannot escape as long as the influencing tube is held near. On removing the tube which holds the negative fluid in bondage, that fluid immediately diffuses itself over the whole egg. An apple, or a turnip, will answer for these experiments at least as well as an egg.