The emitters of the spectral series are without exception single atoms, not compounds of atoms.
The movement of the emitters of the spectral lines may be deduced on the basis of the Doppler principle.
The question of the composition of perceptible objects is one which already occupied the mind of the ancient Greeks.
It is more likely that more than a century will pass before we know the structure of the chemical atoms as thoroughly as we do our solar system.
Thus at the beginning of 1906 it seemed to be established that the emitters of the spectral series of chemical elements are their positive atomic ions.
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.
A beam of luminous hydrogen canal rays has, owing to its velocity, exactly the same direction as that of the electric field in which it may be made to move.
We can in fact first place the beam of rays of moving positive atomic ions in a plane perpendicular to the axis in which we see the spectral lines emitted by them.
By recognizing that the chemical atom is composed of single separable electric quanta, humanity has taken a great step forward in the investigation of the natural world.
By allowing the positive ions to pass through an electric field and thus giving them a certain velocity, it is possible to distinguish them from the neutral, stationary atoms.