The movement of the emitters of the spectral lines may be deduced on the basis of the Doppler principle.

Many scientists will have to contribute to the solution of the great problem; they will have to follow up and measure all those phenomena in which the atomic structure is directly expressed.

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.

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.

Moreover, the abundance of chemical compounds and their importance in daily life hindered the chemist from investigating the question, in what does the individuality of the atoms of different elements consist.

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.