118. We are grieved to interrupt our reader's voyage among the constellations; but the next page crystallizes us again like ants in amber, or worse, in gum-sandarach. It appears, from conclusive and abundant evidence, that the greater cheapness of sandarach, and its easier solubility in oil rendered it the usual substitute for amber, and that the word Vernice, when it occurs alone, is the common synonym for dry sandarach resin. This, dissolved by heat in linseed oil, three parts oil to one of resin, was the Vernice liquida of the Italians, sold in Cennini's time ready prepared, and the customary varnish of tempera pictures. Concrete turpentine ("oyle of fir-tree," "Pece Greca," "Pegola"), previously prepared over a slow fire until it ceased to swell, was added to assist the liquefaction of the sandarach, first in Venice, where the material could easily be procured, and afterwards in Florence. The varnish so prepared, especially when it was long boiled to render it more drying, was of a dark color, materially affecting the tints over which it was passed.[15] * * * "It is not impossible that the lighter style of coloring introduced by Giotto may have been intended by him to counteract the effects of this varnish, the appearance of which in the Greek pictures he could not fail to observe. Another peculiarity in the works of the painters of the time referred to, particularly those of the Florentine and Sienese schools, is the greenish tone of their coloring in the flesh; produced by the mode in which they often prepared their works, viz. by a green under-painting. The appearance was neutralized by the red sandarac varnish, and pictures executed in the manner described must have looked better before it was removed."--_Ib._ p. 252. * * * Farther on, this remark is thus followed out:-- * * *