The art of extracting the metals from their ores, lying, as it does, at the very foundation of the means by which the useful arts advance, cannot be said to have reached a high point of perfection in Greece, Rome, or the other countries from which they derived their supply. An idea of mining processes can scarcely be better given than by a description of those used in the Attic silver mines at Laurium. The veins of silver were situated in a range of pine-covered hills of no considerable height, affording quarries of good marble, in contact with which substance the silver ore was mostly found. These mines were probably opened at a very early period, but the precise date does not appear. The ore, or “silver earth,” as the Greeks called it, was extremely hard and probably very pure and rich in the yield of metal, as the Greeks, from their defective knowledge of chemical processes, could not extract the silver with profit when united with large proportions of other metals. Contrary to common experience, the ore appears to have assumed the form of layers rather than of veins. The mines were worked, either by perpendicular shafts, or by tunneling the side of the hill. Pillars of the ore were of course left, or the superincumbent mass was supported by props of timber, which was largely imported for the purpose. The noxious vapors exhaling from the mines were carried off by shafts of ventilation. The ore was removed partly by simple machines, partly by unassisted labor. On reaching the mouth of the mine it was broken small with iron pestles in stone mortars. These pieces were then ground down smaller, washed, strained through sieves, and sorted into qualities of different richness. The art of smelting the ore thus obtained was imperfect, when viewed in comparison with the greater skill of the moderns. “Even in the time of Strabo, when considerable improvements had been effected, there was still no profit to be gained by the extraction of silver from lead ore, in which it was present in small proportions.”[2] But that some improvement took place is evident from the fact, that much ore rejected by the earlier operators was at a later period profitably employed. Crucibles have been found in Egypt similar to those in modern use. Similar ones were probably known to the Greeks, and old remains of bell-shaped smelting furnaces have been met with, furnished with a channel for the escape of the molten metal, which renders it probable that such furnaces were employed in Greece and Rome.