This point could only be reached by the use of the bellows.

When it was reached, the impurities which floated on the top of the molten metal were skimmed off, or the metal itself allowed, by the turning of a cock, to flow from an upper crucible into a lower one.

For greater purity the melting and skimming process was sometimes repeated; and, in the case of gold, the skimmings were themselves broken up, pounded, and again submitted to the melting pot.[1039] The use of quicksilver, however, being unknown, the gold was never wholly freed from the alloy of silver always found in it, nor was the silver ever wholly freed from an alloy of lead.[1040] The Romans and Carthaginians worked their mines almost wholly by slave labour; and very painful pictures are drawn of the sufferings undergone by the unhappy victims of a barbarous and wasteful system.[1041] The gangs of slaves, we are told, remained in the mines night and day, never seeing the sun, but living and dying in the murky and foetid atmosphere of the deep excavations.

It can scarcely be hoped that the Phoenicians were wiser or more merciful.

They had a large command of slave labour, and would naturally employ it where the work to be done was exceptionally hard and disagreeable.