VII. Colours in metal glasses, in metallic films, and in metallic solutions.—II

Abstract This paper is an extension of a previous memoir on the “Colours in Metal Glasses and in Metallic Films”; it is concerned with the application of mathematical analysis, akin to that already there developed, to the explanation and coordination of the colours which certain metals are, under a great variety of circumstances, capable of causing. From observations on gold and copper ruby glasses, it has been shown that the first stage in the formation of a crystal of those metals is the small sphere; and from observations on the growth of sulphur crystals in CS2, Vogelsang arrived at the conclusion that the small sphere is always the first stage in the formation of a crystal. He remarked, however, that it is by no means necessary that each of the small spheres, formed as crystallisation commences, should give rise to a separate crystal: the small spheres tend to coagulate, forming first rows and then groups of other and more complicated shapes, until the crystal is ultimately formed. To the intermediate bodies he gives the name of crystallites.