Amber; also, the alloy of gold and silver, called electrum.
One of those particles, having about one thousandth the mass of a hydrogen atom, which are projected from the cathode of a vacuum tube as the cathode rays and from radioactive substances as the beta rays; -- called also corpuscle. The electron carries (or is) a natural unit of negative electricity, equal to 3.4 x 10-10 electrostatic units. It has been detected only when in rapid motion; its mass, which is electromagnetic, is practically constant at the lesser speeds, but increases as the velocity approaches that of light. Electrons are all of one kind, so far as known, and probably are the ultimate constituents of all atoms. An atom from which an electron has been detached has a positive charge and is called a coelectron.
We have learnt through experience that when an electrical ray strikes the surface of an atom, an electron, and in some circumstances a second and even a third electron, can be detached. Johannes Stark
The removal of an electron from the surface of an atom - that is, the ionization of the atom - means a fundamental structural change in its surface layer. Johannes Stark
The magnetic cleavage of the spectral lines is dependent on the size of the charge of the electron, or, more accurately, on the ratio between the mass and the charge of the electron. Pieter Zeeman
On the basis of Lorentz's theory, if we limit ourselves to a single spectral line, it suffices to assume that each atom (or molecule) contains a single moving electron. Pieter Zeeman
Now if this electron is displaced from its equilibrium position, a force that is directly proportional to the displacement restores it like a pendulum to its position of rest. Pieter Zeeman
