Eretria was named from the place where it was found. Pliny gives its medical properties, but does not inform us of its colour. It is impossible to say what it was.
Auripigmentum was yellow sulphuret of arsenic. It was probably but little used as a pigment by the ancient painters.
Cerussa usta was red lead.
Sandaracha was red sulphuret of arsenic. The pound of sandaracha cost 5 as.: it was imitated by red lead. Both it and ochra were found in the island Topazos in the Red Sea.
Sandyx was made by torrefying equal parts of true sandaracha and sinopis. It cost half the price of sandaracha. Virgil mistook this pigment for a plant, as is obvious from the following line:
Sponte sua sandix, pascentes vestiet agnos.[70]
Siricum is made by mixing sinopis and sandyx.
Atramentum was obviously from Pliny’s account of it lamp-black. He mentions ivory-black as an invention of Apelles: it was called elephantinum. There was a native atramentum, which had the colour of sulphur, and got a black colour artificially. It is not unlikely that it contained sulphate of iron, and that it got its black colour from the admixture of some astringent substance.
The ink of the ancients was lamp-black mixed with water, containing gum or glue dissolved in it. Atramentum indicum was the same as our China ink.
The purpurissum was a high-priced pigment. It was made by putting creta argentaria (a species of white clay) into the caldrons containing the ingredients for dying purple. The creta imbibed the purple colour and became purpurissum. The first portion of creta put in constituted the finest and highest-priced pigment. The portions put in afterwards became successively worse, and were, of consequence lower priced. We see, from this description, that it was a lake similar to our modern cochineal lakes.[71]