Among the remaining colours which, as already stated,[1910] owing to their dearness are furnished by the employer, purpurissum holds the highest rank. For the purpose of preparing it, argentaria or silver chalk[1911] is dyed along with purple[1912] cloth, it imbibing the colour more speedily than the wool. The best of all is that which, being thrown the very first into the boiling cauldron, becomes saturated with the dye in its primitive state. The next best in quality is that which has been put into the same liquor, after the first has been removed. Each time that this is done, the quality becomes proportionally deteriorated, owing, of course, to the comparative thinness of the liquid. The reason that the purpurissum of Puteoli is more highly esteemed than that of Tyre, Gætulia, or Laconia, places which produce the most precious kinds of purple, is the fact that it combines more readily with hysginum,[1913] and that it is made to absorb the colouring liquid of madder. The worst purpurissum is that of Lanuvium.[1914]
The price of purpurissum is from one to thirty denarii per pound. Persons who use it in painting, place a coat of sandyx beneath; a layer on which of purpurissum with glair of egg, produces all the brilliant tints of minium. If, on the other hand, it is their object to make a purple, they lay a coat of cæruleum[1915] beneath, and purpurissum, with egg,[1916] upon it.
CHAP. 27.—INDICUM.
Next in esteem to this is indicum,[1917] a production of India, being a slime[1918] which adheres to the scum upon the reeds there. When powdered, it is black in appearance, but when diluted in water it yields a marvellous combination of purple and cæruleum. There is another[1919] kind, also, which floats upon the surface of the pans in the purple dye-houses, being the scum which rises upon the purple dye. Persons who adulterate it, stain pigeons’ dung with genuine indicum, or else colour Selinusian[1920] earth, or anularian[1921] chalk with woad.
The proper way of testing indicum is by laying it on hot coals, that which is genuine producing a fine purple flame, and emitting a smell like that of sea-water while it smokes: hence it is that some are of opinion that it is gathered from the rocks on the sea-shore. The price of indicum is twenty denarii per pound. Used medicinally, it alleviates cold shiverings and defluxions, and acts as a desiccative upon sores.
CHAP. 28.—ARMENIUM; ONE REMEDY.
Armenia sends us the colouring substance which is known to us by its name.[1922] This also is a mineral, which admits of being dyed, like chrysocolla,[1923] and is best when it most closely resembles that substance, the colour being pretty much that of cæruleum. In former times it was sold at thirty sesterces per pound; but there has been found of late in the Spanish provinces a sand which admits of a similar preparation, and consequently armenium has come to be sold so low as at six denarii per pound. It differs from cæruleum in a certain degree of whiteness, which causes the colour it yields to be thinner in comparison. The only use made of it in medicine is for the purpose of giving nourishment to the hair, that of the eyelids in particular.
CHAP. 29.—APPIANUM.
There are also two colours of very inferior quality, which have been recently discovered. One of these is the green known as “appianum,”[1924] a fair imitation of chrysocolla; just as though, we had not had to mention sufficient of these counterfeits already. This colour, too, is prepared from a green chalk, the usual price of it being one sesterce per pound.