Without entering into details, I will give the conclusions I then arrived at in the very words I used:—
‘1. The elements, if arranged according to their atomic weights, exhibit an evident periodicity of properties.
‘2. Elements which are similar as regards their chemical properties have atomic weights which are either of nearly the same value (e.g. platinum, iridium, osmium) or which increase regularly (e.g. potassium, rubidium, cæsium).
‘3. The arrangement of the elements, or of groups of elements, in the order of their atomic weights, corresponds to their so-called valencies as well as, to some extent, to their distinctive chemical properties—as is apparent, among other series, in that of lithium, beryllium, barium, carbon, nitrogen, oxygen, and iron.
‘4. The elements which are the most widely diffused have small atomic weights.
‘5. The magnitude of the atomic weight determines the character of the element, just as the magnitude of the molecule determines the character of a compound.
‘6. We must expect the discovery of many yet unknown elements—for example, elements analogous to aluminium and silicon, whose atomic weight would be between 65 and 75.
‘7. The atomic weight of an element may sometimes be amended by a knowledge of those of the contiguous elements. Thus, the atomic weight of tellurium must lie between 123 and 126, and cannot be 128.
‘8. Certain characteristic properties of the elements can be foretold from their atomic weights.