CHAP. 56.—SIL: THE PERSONS WHO FIRST USED IT IN PAINTING, AND THE METHOD THEY ADOPTED.
In the mines of gold and silver there are some other pigments also found, sil1152 and cæruleum. Sil is, properly speaking, a sort of slime.1153 The best kind is that known as Attic sil; the price of which is two denarii per pound. The next best kind is the marbled1154 sil, the price of which is half that of the Attic kind. A third sort is the compressed sil, known to some persons as Scyric sil, it coming from the Isle of Scyros. Then, too, there is the sil of Achaia, which painters make use of for shadow-painting, and the price of which is two sesterces per pound. At a price of two asses less per pound, is sold the clear1155 sil, which comes from Gaul. This last kind, as well as the Attic sil, is used for painting strong lights: but the marbled sil only is employed for colouring compartitions,1156 the marble in it offering a resistance to the natural acridity of the lime. This last kind is extracted also from some mountains twenty miles distant from the City. When thus extracted, it is submitted to the action of fire; in which form it is adulterated by some, and sold for compressed sil. That it has been burnt, however, and adulterated, may be very easily detected by its acridity, and the fact that it very soon crumbles into dust.
Polygnotus1157 and Micon1158 were the first to employ sil in painting, but that of Attica solely. The succeeding age used this last kind for strong lights only, and employed the Scyric and Lydian kinds for shadow painting. The Lydian sil used to be bought at Sardes; but at the present day we hear nothing of it.