CRYSTALLUS.                                    173
	The Crystal (Pure Silica) is reckoned by Theophrastus (30) amongst the stones used in rings, where he speaks of it with the Amethyst, adding "both are transparent." This joint mention shows his knowledge of the true nature of the latter, as being merely an accidentally coloured Crystal. It is curious that, in spite of this inclusion in his list, intagli of the Greek, or indeed of the Roman period, upon Crystal, are unknown to collectors. Herodotus (iii. 24) mentions a stone by the name of ϋαλος, which, if there be any truth at tho bottom of his story, must have been Rock-salt, judging from its magnitude and facility in working. "The corpse (of the defunct Ethiopian amongst the Macrobii), after having been dried, whether in the Egyptian or some other manner, is coated with plaster, and painted so as to imitate life, and then put inside of a hollow pillar of hyalus, which is dug up there in large quantities, and easily worked ; and the corpse, being enclosed within the pillar, shows through it, without producing a stench or anything unpleasant, and wearing all the clothes he used in life." The Crystal, however, was in enormous request amongst the luxurious Romans under the Empire for the purpose of making drinking-cups, valued as highly as the Murrhina, with which they are generally associated in the allusions of the satirists. An equal mania possessed the fashionable Romans for the acqui­sition of each sort, the Crystal being appropriated to iced, the other to boiling liquors. Thus Pliny instances a lady, and she not a wealthy one, who had then lately bought a Crystal trulla (flat bowl) for a sum equivalent to 1500 l. of our money. Nero, to revenge himself upon mankind by preventing any one else from drinking out of them, when informed that all was lost,