Black lead is not procured in Gallæcia, although it is so greatly abundant in the neighbouring province of Cantabria; nor is silver procured from white lead, although it is from black.[1706] Pieces of black lead cannot be soldered without the intervention of white lead, nor can this be done without employing oil;[1707] nor can white lead, on the other hand, be united without the aid of black lead. White lead was held in estimation in the days even of the Trojan War, a fact that is attested by Homer, who calls it “cassiteros.”[1708] There are two different sources of black lead: it being procured either from its own native ore, where it is produced without the intermixture of any other substance, or else from an ore which contains it in common with silver, the two metals being fused together. The metal which first becomes liquid in the furnace, is called “stannum;”[1709] the next that melts is silver; and the metal that remains behind is galena,[1710] the third constituent part of the mineral. On this last being again submitted to fusion black lead is produced, with a deduction of two-ninths. CHAP. 48. (17.)—STANNUM. ARGENTARIUM. When copper vessels are coated with stannum,[1711] they produce a less disagreeable flavour, and the formation of verdigris is prevented; it is also remarkable, that the weight of the vessel is not increased. As already mentioned,[1712] the finest mirrors were formerly prepared from it at Brundisium, until everybody, our maid-servants even, began to use silver ones. At the present day a counterfeit stannum is made, by adding one-third of white copper to two-thirds of white lead.[1713] It is also counterfeited in another way, by mixing together equal parts of white lead and black lead; this last being what is called “argentarium.”[1714] There is also a composition called “tertiarium,” a mixture of two parts of black lead and one of white: its price is twenty denarii per pound, and it is used for soldering pipes. Persons still more dishonest mix together[1715] equal parts of tertiarium and white lead, and, calling the compound “argentarium,” coat articles with it melted. This last sells at sixty denarii per ten pounds, the price of the pure unmixed white lead being eighty denarii, and of the black seven.[1716]