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Certain characteristic properties of elements can be foretold from their atomic weights.

The elements, if arranged according to their atomic weights, exhibit an apparent periodicity of properties.

The elements which are the most widely diffused have small atomic weights.

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 body.

The body tends to treat elements in the same column of the periodic table as equivalents.

Experimental work of great refinement is necessary in order to determine atomic weights. No relationships between them have yet been certainly found which make it possible for us to compute by any sort of calculation exactly the value of any one atomic weight from any other.

The most common and most important result of them is that the nature and size of the effect on corresponding series of different elements are largely an expression of the peculiarity of their atomic structure - or, at least, of the structure of the surface.

We must expect the discovery of many as yet unknown elements-for example, elements analogous to aluminum and silicon- whose atomic weight would be between 65 and 75.

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.

In chemical terms, radium differs little from barium; the salts of these two elements are isomorphic, while those of radium are usually less soluble than the barium salts.