William Nicol (geologist)
He was born in Humbie (East Lothian) in 1770 and his baptism is recorded in the parish register; many sources give an incorrect date of birth. For example, the Royal Society of Edinburgh gives a date of birth of 1768, and his gravestone gave a date of birth of 1766.
He started out as aide to his uncle, Henry Moyes, an itinerent lecturer in Natural Philosophy whose blindness necessitated assistance for his chemistry and optics demonstrations. Nicol, having himself become a popular lecturer on that subject at the University of Edinburgh, settled in Edinburgh to live a very retired life. He conducted extensive studies of fluid inclusions in crystals and the microscopic structure of fossil wood. He did not publish any of his research findings until 1826.
Nicol made his prism by bisecting a parallelepiped of Iceland spar (a naturally occurring, transparent crystalline form of calcium carbonate) along its shortest diagonal, then cementing the two halves together with Canada balsam. Light entering the prism is refracted into two rays, one of which emerges as plane-polarized light. Nicol prisms greatly facilitated the study of refraction and polarization, and were later used to investigate molecular structures and optical activity of organic compounds.
In 1815, Nicol developed a method of preparing extremely thin sections of crystals and rocks for microscopical study. His technique (which involved cementing the specimen to a glass slide and then carefully grinding until it was extremely thin) made it possible to view mineral samples by transmitted rather than reflected light and therefore enabled the minerals' internal structures to be seen.
Death and legacy
- Joseph Priestley to Joseph Banks, 6 Feb 1783, NHM, Dawson Turner MS 3, fol. 17
- p122 Albert Edward Musson, Eric Robinson Science and technology in the Industrial Revolution, Manchester University Press, 1969, ISBN 0-7190-0370-9
- This article incorporates text from a publication now in the public domain: Chisholm, Hugh, ed. (1911). Encyclopædia Britannica (11th ed.). Cambridge University Press