Kermes is the Arabic name for this insect.
It should be remembered that a large number of the mediaeval receipts and processes were not based on any reasonable principle, and endless complications were often introduced quite needlessly; this is well shown in a very interesting paper by Prof. John Ferguson of Glasgow on Some Early Treatises on Technological Chemistry, read before the Philos. Soc. Glasgow, Jan. 6, 1886.
The use of litharge as a drier was one of the most important improvements made in the technique of oil painting by the Van Eycks of Bruges in the first half of the fifteenth century. Before then, oil paintings on walls had often been laboriously dried by holding charcoal braziers close to the surface of the picture. Among the accounts of the expenses of painting the Royal Palace of Westminster in the thirteenth century (see above, page [110]) charcoal for this purpose is an important item in the cost. Paintings on panel, being moveable, were usually dried by being placed in the sun; but, in every way, a good drier like litharge answers better than heat, either of the fire or of sunshine.
See Theophilus, I. 39.
See Vitruvius, VII. 10; and Pliny, Hist. Nat. XXXV. 41; and Dioscorides, V. 183.