Scanned text contains errors.
to Cydtas, a contemporary of Euphranor (Theophr., I.e. 53). Another mineral supplying a red, sometimes a yellow, pigment, was sandarach (Gr. sanddrdche"; Lat. sanddrdca'), found in Paphlagoma, probably disulphide of arsenic (" realgar"). As this mineral is poisonous, the mortality in the mines was very high. An artificial substitute, called cerussa usta, or usta alone, was therefore generally preferred. This was obtained by burning white lead, a discovery attributed to the painter Niclas (Pliny, xxxv 38). The result is " red lead," i.e. red oxide of lead. There was besides a colour compounded of equal parts of ruddle and sandarach, called sandyv (Pliny, xxxv 40), which is also the designation of a natural pigment of which little is known (Vergil, Eel. iv 45). Of greater importance than these is cinnabar (Gr. originally kinndbdrl, afterwards ammton / Lat. minium}, found in Spain, especially at Sisfipo (Pliny, xxxiii 121). An artificial kind was made at Ephesus from the red sand of the agri CilbidnT. This discovery is assigned to Calllas (ib. 113). The name cinnabari was often erroneously given to a red resin, now called dragon's blood, and produced from the cdlamus draco, a kind of palm growing in the Sunda Islands and elsewhere. The ancients probably imported it from the island of Socotra, as it is a product of the Somali coast on the adjacent mainland of Africa.—A purple pigment (Gr. ostreiOn ; Lat. ostrum, purpurissum} was prepared by mixing cretd argentdrld with the purple secretion of the murex (see purple) ; the best kind was made at PuteSli (Pliny xxxv 45). Slue. The pigment used from the earliest times was called in Greek kydnSs, in Latin ccerulium, a blue silicate of copper, generally mixed with carbonate of lime (chalk). It is not to be confounded with the modern cwruleuvi, which is stan-nate of cobalt. Kydnds was found in small ! quantities in copper mines, and artificial kinds were made in Scythia, Cyprus, and Egypt (Theophr., I.e. 51, 55). Vitruvius mentions only the artificial cieruleum of : Alexandria and PuteSli. The method of | manufacturing it was brought from Egypt by Vestorius. It was prepared by heating strongly together sand,_/Zfls nitri (carbonate of soda), and filings of copper. This " Egyptian azure" was reproduced by Sir Humphry Davy, by taking fifteen parts by weight of carbonate of soda, twenty of powdered opaque flints, and three of copper filings, and heating them strongly for two i
hours. The product, when pulverized, supplied a fine deep sky blue. The " Alexandrian frit " is in part a species of artificial lapis lazuli, the colouring matter of which is naturally inherent in a hard siliceous stone (Phil. Trans. Royal Society, 1815, p. 121). It was not available for fresco-painting, but could be used for painting in tempera (Pliny, xxxiii 162). The name kydnos was given to a blue mineral, which is to be identified as lapis lazuli, a silicate of sodium, calcium, and aluminium, with a sulphur compound of sodium. This was pounded into a pigment, now known as ultramarine. Kyanos was also the name of the blue carbonate of copper from the copper mines of Cyprus, where lapis lazuli i is not to be found. Artificial blue pigments were produced by colouring pulverized glass with carbonate of copper. "Armenian blue " (Gr. Armenian) is described by Pliny (xxxv 47) as made from a mineral like chrysocolla (malachite ?) in colour, the best kinds being almost as good as cceruleum. It is probably a kind of ultramarine.—Indigo (indictim) was also used. The way in which it is mentioned in Vitruvius (vii 9, 6, and 10, 4) implies that it had been recently introduced. It could not be used for frescoes. Modern experiment has proved that the colouring basis of the blue found in ancient mural paintings is oxide of copper. Cobalt has also been discovered in ancient specimens of transparent blue glass. Green. Several pigments were in use : (1) chrysOcolla (or malachite ?, hydrated dicarbonate of copper), pounded and sifted, and mixed with alum and woad (luium, Pliny, xxxiii 87). Malachite green, sometimes called mountain, or Hungary, green, is also a modern pigment. (2) Cretd vlrldls, the best kind of which came from Smyrna (Vitruv., vii 7, 4). It is a species of ochre containing silica, oxide of iron, magnesia, potash, and water; and is still used under the names of terra verte, verdetta, green earth, Verona green, green bice, or holly green. (3) Verdigris (Gr. Ids ; Lat. cerugo, ceruca, Vitruv., vii 12, 1). This is an acetate of copper (sometimes crystallized), i.e. a compound of acetic acid and oxide of copper. Malachite green and Verona green have both been traced in ancient paintings. Verdigris has not been found ; hence it has been conjectured by Sir H. Davy, that what was originally a diacetate of copper has in the course of centuries changed into carbonate of copper (I.e., p. 112). It is described as " the least durable of copper greens; light