The Periodic Table

In 1922, the English-born (and New Zealand-educated) chemist J. W. Mellor published the first of 16 volumes which constituted his Comprehensive Treatise on Inorganic and Theoretical Chemistry — perhaps the greatest single-handed effort in the whole of the chemical literature. In explaining the arrangement of his material, he wrote: ‘We now flatter ourselves that the Periodic Law has given inorganic chemistry a scheme of classification which enables the facts to be arranged and grouped in a scientific manner. The appearance of order imparted by that guide is superficial and illusory. Allowing for certain lacunae in the knowledge of the scarcer elements, prior to the appearance of that Law, the arrangements employed by the earlier chemists were just as satisfactory and in some cases, indeed, more satisfactory than those based on the Periodic Law. The arrangement of the subject matter of inorganic chemistry according to the periodic scheme is justified solely by expediency and convention. It has a tendency to make teachers over-emphasise unimportant and remote analogies, and to underestimate important and crucial differences.’

These views were certainly worthy of respect in 1922; Mellor, who was already well known as an author, probably knew as much factual inorganic chemistry as anyone alive.