Martin Lister (1639-1712) and fools' gold.

Seventeenth-century physician Martin Lister is best known for his work in natural history and participation in the early Royal Society. However, little attention has been focused upon Lister's work in chemistry, the most salient examples being his analysis of pyrites or "fools' gold" near mineral springs in the De Fonbibus medicatis Angliae Exercitatio of 1684 (Exercises on the healing springs of England), his contributions to the Philosophical Transactions in the 1670s and 1680s, and his unpublished manuscript " A Method for the History of Iron, Imperfect." He defined pyrites more specifically as " ironstone marcasites" which were "nothing else but a body of iron disguised under a vitriolic varnish"; "vitriol" referred to iron (II) sulfate which occurred as a weathering product of pyrites. This paper demonstrates that an understanding of Lister's work on pyrites and vitriol is best attained by placing him in the intellectual context of the seventeenth-century chemical debate about minerallogenesis. Lister believed that the volatile exhalations of pyrites and its vitriol in the air were important in the transformation of matter, and he subscribed to the sixteenth-and seventeenth-century theory of witterung (weathering) or ore exhalations as an explanation for the formation of minerals. Despite his allegiance to the theories of witterung, I will illustrate that Lister made use of his interests in natural history to go one step beyond them, postulating that the sulfurous exhalations from pyrites were responsible for the heating of hot springs, as well as meteorological and geological effects.