Fifteenth Experiment.
A dry wig or bunch of horse-hair when combed becomes electrical, and likewise affects the leaves of the electroscope.
Sixteenth Experiment.
Two dry silk ribbons, the one white and the other black, passed rapidly together through the fingers, exhibit sparks and flashes of light when drawn asunder, and also cause the gold leaves to repel each other.
Seventeenth Experiment.
Much instructive amusement is afforded by testing the gold leaves when separated from each other during either of the former experiments, with an excited piece of sealing-wax. If the electricity produced is negative, they repel each other further when the excited wax is approached; if positive, they fall when the excited wax is brought near them.
Eighteenth Experiment.
When fresh, dry, ground coffee is received on to the disc of the electroscope, as it falls from the mill, powerful electrical excitation is displayed, and this is sometimes so apparent, that the particles cling around the lower part of the mill or to the sides of the cup or basin held to catch it.
Nineteenth Experiment.
After playing a tune on a violin, hold the bow (well rosined) to the electroscope, when the usual divergence of the leaves will be apparent.