Page:Proceedings of the Royal Society of London Vol 60.djvu/29

Rh race, proceeded westw ard from its early home in the east is a fair subject for speculation. B ut, under any circum stances, this discovery aids in bridging over the interval betw een palaeolithic m an in Britain and in India, and adds another link to the chain of evidence by which the original cradle of the hum an fam ily m ay eventually be identified, and tends to prove th e unity of race between the inhabitants of Asia, Africa, and Europe, in Palaeolithic tim es.

The molecular distribution of th e m etals in alloys of gold and of metals of the platinum group has been described by me a t some length, in a series of papers w hich have already been published by the Royal Society.* New interest in the subject has, however, arisen in connexion w ith the extraordinary development in various parts of the world especially in South Africa, of certain processes w hich are now employed for extracting gold from its ores. T heir use has been attended w ith the introduction into this country of a series of alloys of gold and the base m etals w hich have hitherto rarely been m et with in m etallurgical industry. The base m etals associated w ith the gold in these cases are usually the very ordinary ones lead aijd zinc, but their presence in the gold has given rise to unexpected difficulties, as the distribution of the precious m etal in the ingots which reach this country is so peculiar, th at it is not possible to estim ate the value of the ingots by taking th e pieces of m etal required for the assay, by any of the well-known m ethods now in use.

The grouping of the m etal in these ingots presents m uch scientific as well as industrial interest, and the following is a brief statement of the facts which have been observed.

A. An ingot of gold weighing 3'545 kilogram s was assayed w ith a view to subjecting it to the ordinary operation of refining. A piece of metal was, therefore, cut from the base of the ingot at the point marked A, and the following are the results of four assays made on this piece of m e ta l:—

Gold 1 ................ 665-8 2 ................ 663-6 3 ................ 662-4 4 ................ 658-0 Average .... 662-45


 * ‘ Phil. Trans.,’ A, vol. 183, p. 629,1892. ‘ Roy. Soc. Proc.,’ vol. 47, p. 180, 1890.