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.

With this in mind, for some twenty years I have set myself as my particular task the experimental investigation of the connexion between change in the structure and change in the spectra of chemical atoms.

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.

The question of the composition of perceptible objects is one which already occupied the mind of the ancient Greeks.

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.

The emitters of the spectral series are without exception single atoms, not compounds of atoms.

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.