Note 4 — Chapter VI · TRACHYTE AND BASALT.—DISTRIBUTION OF VOLCANIC ISLES.

A full and interesting account of this discovery, by Mr. Pattinson, was read before the British Association in September 1838. In some alloys, according to Turner (“Chemistry,” p. 210), the heaviest metal sinks, and it appears that this takes place whilst both metals are fluid. Where there is a considerable difference in gravity, as between iron and the slag formed during the fusion of the ore, we need not be surprised at the atoms separating, without either substance being granulated.