William Nicol (geologist)

[2]) He started out as aide to his uncle, Henry Moyes, an itinerant lecturer in Natural Philosophy whose blindness necessitated assistance for his chemistry and optics demonstrations.

Besides the prism that bears his name, he conducted extensive studies of fluid inclusions in crystals and the microscopic structure of fossil wood.

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.

Nicol prisms greatly facilitated the study of refraction and polarization, and were later used to investigate molecular structures and optical activity of organic compounds.

He took a slice from the specimen to be studied, ground it perfectly flat, polished it, and cemented it by means of Canada balsam to a piece of plate-glass.