The discovery of various phenomena has led to a recognition of the fact that the chemical atom is an individual which again is itself made up of several units into a selfcontained whole.

The discovery of various phenomena has led to a recognition of the fact that the chemical atom is an individual which again is itself made up of several units into a selfcontained whole.

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.

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.

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.

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.