Mass defect curve and nuclear constitution

In the discussion before the Royal Society on the constitution of the atomic nucleus held on February 7, 1929,* I proposed a simple model of a nucleus built from α-particles in a way very similar to a water-drop held together by surface tension. A certain number of protons (not more than three) and electrons can be bound to such an α-aggregate without forming a new α-particle. † Such additional units of nuclear constitution, usually bound less strongly than those involved in the α-particles, we shall term free nuclear protons and electrons. Their presence will, of course, affect the form of the nuclear energy curve (mass defect curve), not changing, however, its general shape. In the present paper I shall attempt to treat the problem more closely, analysing from the theoretical point of view the experimental facts concerning the nuclear energy.