Volcanic matter from the Solfaterra, southern Italy, c 1770.

Hand-coloured etching by Peter Fabris (active 1768-1779). Illustrated plate from William Hamilton's study of Italian volcanoes, 'Campi Phlegraei' (published in Naples, 1776). Fragments of volcanic matter collected by Hamilton from the Solfaterra, showing calcined stone, virgin sulphur, cinnabar, pumice stones, lava and crystals of alum. Based on letters to the Royal Society. Hamilton's book is a seminal study of the nature and effects of volcanic activity.