[505] One instance of its being used for this purpose is found in Ammianus Marcellinus, lib. xx. c. 12.
[506] [This cannot be correct; for Geber, who is supposed to have lived in the eighth century, was acquainted with three kinds of it, and describes the method of preparing burnt alum.]
[507] Joh. Serapionis Arabis de simplicibus medicinis opus, cap. 410.
[508] Reisebeschreibung, ii. p. 408, 409.
[509] This singular appellation occurs in Valentini Historia Simplicium, and several other works.
[510] Jul. Cæs. Scaligeri Exot. exercitat. Franc. 1612, 8vo, p. 325.
[511] I shall here take occasion to remark, that schist seems to have been employed for making alum in the time of Agricola, as appears by his book De Ortu et Causis Subterraneorum, p. 47.
[512] Mercati, Metallotheca, p. 54.
[513] Pyrotechnia. Ven. 1559, 4to.
[514] Leibnitii Protogæa, p. 47.