The theory of valency thus founded has dominated the subsequent development of chemical doctrine, and forms the groundwork upon which the fabric of modern structural chemistry reposes.

When multiplied by the valency it gives the atomic weight.

Faraday's Law.—Faraday found that the quantity of electricity required to liberate one gramme-molecule of any radical is 96.537 coulombs for each valency of the radical.

The effectiveness of the various electrolytes in bringing about this change is proportional to their valency; bivalent ions are from 70 to 80 times, and trivalent ions about 600 times as effective as monovalent ions.

A general classification of elements, however, was not realized by Frankland, nor even by Odling, who had also investigated the question from the valency standpoint.