Principles of Electricity by Maynard Shipley

The science of electricity is based upon observation of those phenomena of attraction and repulsion which are comprehended under the term _electrostatics_. Statical electricity, so named from a Greek word (statikos), which means "causing to stand (or stay),"-also called _frictional electricity_-is the electricity of stationary charges caused by rubbing together unlike bodies, such as glass and silk (noted in Chapter II). In such cases equal and opposite charges of electricity are always produced. The term _statical electricity_ applies properly, however, to the electricity of all stationary charges, however produced.

The electricity upon the surface of glass is called positive electricity; that upon rubber, negative electricity. When silk is rubbed upon glass it receives a negative charge from the glass and confers a positive charge upon the silk. Wool or fur rubbed on wax or rubber receives a positive charge in exchange for a negative charge; "equal and opposite charges of electricity are always produced. " A piece of glass and a piece of silk attract one another; two pieces of silk or two pieces of glass or wax repel one another, because a body which is positively charged is attracted by one negatively charged and repelled by one negatively charged, and vice versa. A piece of glass rubbed by a piece of silk, under suitable conditions, attracts any other body with which it has not been in contact. The piece of silk will do likewise. In all these cases, the attraction or repulsion becomes weaker with increase of distance between the attracting and repelling bodies.