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ONYX.
237
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way with the prices quoted repeatedly by the same author (xxx. 35) as paid for silver chasings by the old and eminent cœlatores. Similarly
Apuleius, in describing the banquet given by the wealthy Byrrhena,
enumerates " ampli calices varias quidem gratiœ, sed pretiositatis
unius. Hic, vitrum fabre sigillatum, ibi crystallum impunctum,
argen-tum alibi clarum atque aurum fulgurans, et succinum mire cavatum
in capides ut bibas." Here it will bo observed he makes the glass
vessels to be adorned with figures in relief, the crystal with such in intaglio—a distinction confirmed by all the specimens extant in either kind.
De
Boot states that the species composed of black and white layers was
commonly forged in his times in order to be sold for a real cameo, in
the following curious manner (ii. 94) :—" Take the little sea-shells
used by the Italian women for paint (pearl-powder?), grind them fine;
then steep the powder in lemon-juice, frequently passed through a
filter, so that the juice be three or four fingers deep over it. Let
the mixture stand thus, well covered over, for ten days in a warm place
; then pour off the juice ; wash the residuum in water ; grind it up in
a porphyry mortar with white of egg well beaten up beforehand ; then
cast the cement in moulds of the required design, made in wax. Next
polish with great nicety the rough back of these casts, so that they
may be applied skilfully and neatly upon a black ground, that the
deception may not be readily detected. In rubbing down the shells,
other colours can be added in fine powder, so that the Sardonyx may be
imitated in this way as well as the other precious stones."
Georgius
Agricola (who died in 1485) has a passage interesting as showing how
rapidly the newly-revived art of gem-engraving had found its way into
Germany :— " Nowadays, in the opaque white crust of the German Onyx
(Agathe-onyx), engravers cut the ooats-of-arms on which
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