Note 2261 — BOOK XXXV. AN ACCOUNT OF PAINTINGS AND COLOURS. (continued 2)

Beckmann is of opinion that our alum was not known to the Greeks or Romans, and that what the latter called “alumen” was green vitriol, or sulphate of the protoxide of iron, in an impure state. Hist. Inv. Vol. I. p. 180. Bohn’s Edition. Dr. Pereira remarks, however, that “there can be little doubt that Pliny was acquainted with our alum, but did not distinguish it from sulphate of iron, for he informs us that one kind of alum was white, and was used for dyeing wool of bright colours.” Materia Medica, Vol. I, Delafosse identifies the “alumen” of Pliny with double sulphate of alum and iron.