Eretria takes its name from the territory[1894] which produces it. Nicomachus[1895] and Parrhasius made use of it. In a medicinal point of view, it is cooling and emollient. In a calcined state, it promotes the cicatrization of wounds, is very useful as a desiccative, and is particularly good for pains in the head, and for the detection of internal suppurations. If the earth, when applied[1896] with water, does not dry with rapidity, the presence of purulent matter is apprehended. CHAP. 22.—SANDARACH. According to Juba, sandarach and ochra are both of them productions of the island of Topazus,[1897] in the Red Sea; but neither of them are imported to us from that place. The mode of preparing sandarach we have described[1898] already: there is a spurious kind also, prepared by calcining ceruse in the furnace. This substance, to be good, ought to be of a flame colour; the price of it is five asses per pound. CHAP. 23.—SANDYX. Calcined with an equal proportion of rubrica, sandarach forms sandyx;[1899] although I perceive that Virgil, in the following line,[1900] has taken sandyx to be a plant— “Sandyx itself shall clothe the feeding lambs.” The price of sandyx[1901] is one half that of sandarach; these two colours being the heaviest of all in weight. CHAP. 24.—SYRICUM. Among the artificial colours, too, is syricum, which is used as an under-coating for minium, as already[1902] stated. It is prepared from a combination of sinopis with sandyx. CHAP. 25.—ATRAMENTUM. Atramentum,[1903] too, must be reckoned among the artificial colours, although it is also derived in two ways from the earth. For sometimes it is found exuding from the earth like the brine of salt-pits, while at other times an earth itself of a sulphurous colour is sought for the purpose. Painters, too, have been known to go so far as to dig up half-charred bones[1904] from the sepulchres for this purpose. All these plans, however, are new-fangled and troublesome; for this substance may be prepared, in numerous ways, from the soot that is yielded by the combustion of resin or pitch; so much so, indeed, that manufactories have been built on the principle of not allowing an escape for the smoke evolved by the process. The most esteemed black,[1905] however, that is made in this way, is prepared from the wood of the torch-pine. It is adulterated by mixing it with the ordinary soot from furnaces and baths, a substance which is also employed for the purpose of writing. Others, again, calcine dried wine-lees, and assure us that if the wine was originally of good quality from which the colour is made, it will bear comparison with that of indicum.[1906] Polygnotus and Micon, the most celebrated painters of Athens, made their black from grape-husks, and called it “tryginon.”[1907] Apelles invented a method of preparing it from burnt ivory, the name given to it being “elephantinon.”