‹‹‹ Vitr. 7.14.1 | Table of Contents | Vitr. 7.14.3 ›››
2In the same way an excellent purple is obtained by preparing vaccinium, and mixing it with milk. So also, those who cannot afford the use of chrysocolla, mix blue with the herb weld, and thus obtain a brilliant green. These are called factitious colours. On account of the dearness of indigo, Selinusian chalk, or that used for making rings, is mixed with glass, which the Greeks call ὑαλος; and thus they imitate indigo.
2They make a fine purple colour by treating bilberry in the same way and mixing it with milk. Those who cannot use malachite green on account of its dearness, dye blue with the plant called dyer’s weed, and thus obtain a most vivid green. This is called dyer’s malachite green. Again, for want of indigo, they dye Selinusian or anularian chalk with woad, which the Greeks call ἱσἁτις, and make an imitation of indigo.