Elementary Treatise on Natural Philosophy, Vol. 3 of 4 (Classic Reprint)

to that produced by the contact of a cobweb. If the knuckle be held near the tube, a pecliar crackling noise is heard, and a bright spark passes between the tube and knuckle. The tube then has acquired peculiar properties by the application of friction. It is said to be electrified, and the flame of eleciricity is given to the agent in which the various phenomena just described are attributed. Glass is not the only substance which can be electrified by friction; the same property is possessed also by resin, sulphur, precious stones, amber, &c. The Greek name of this last substance is the root from which the word electricity is derived. At first sight it appears that this property of becoming electrificd by friction is not common to all bodies; for if a bar of metal be held in the hand and rubbed with wool, it does not acquire the properties

Table of Contents

Fundamental phenomena of frictionol electricity, 555 Conductors anll non