Pieces of lava from Mount Vesuvius, c 1770.
© Science Museum / Science & Society Picture Library
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). Specimens of lava taken from the crater of Vesuvius, showing (1) lava covered with sulphur, (2) lava from the the platform within the crater, (3) fistular salts, (4) pumice stones impregnated with sulphur and (5,6) lava impregnated with salt and sulphur. Hamilton's book is a seminal work on the nature and effects of volcanic activity.