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]
White lead is naturally more dry; while the black, on the contrary, is always moist; consequently the white, without being mixed with another metal, is of no use[1717] for anything. Silver too, cannot be soldered with it, because the silver becomes fused before the white lead. It is confidently stated, also, that if too small a proportion of black lead is mixed with the white, this last will corrode the silver. It was in the Gallic provinces that the method was discovered of coating articles of copper with white lead, so as to be scarcely distinguishable from silver: articles thus plated are known as “incoctilia.”[1718] At a later period, the people of the town of Alesia[1719] began to use a similar process for plating articles with silver, more particularly ornaments for horses, beasts of burden, and yokes of oxen: the merit, however, of this invention belongs to the Bituriges.[1720] After this, they began to ornament their esseda, colisata, and petorita[1721] in a similar manner; and luxury has at last arrived at such a pitch, that not only are their decorations made of silver, but of gold even, and what was formerly a marvel to behold on a cup, is now subjected to the wear and tear of a carriage, and this in obedience to what they call fashion!
White lead is tested, by pouring it, melted,[1722] upon paper, which ought to have the appearance of being torn rather by the weight than by the heat of the metal. India has neither copper nor lead,[1723] but she procures them in exchange for her precious stones and pearls.
CHAP. 49.—BLACK LEAD.
Black lead[1724] is used in the form of pipes and sheets: it is extracted with great labour in Spain, and throughout all the Gallic provinces; but in Britannia[1725] it is found in the upper stratum of the earth, in such abundance, that a law has been spontaneously made, prohibiting any one from working more than a certain quantity of it. The various kinds of black lead are known by the following names—the Ovetanian,[1726] the Caprariensian,[1727] and the Oleastrensian.[1728] There is no difference whatever in them, when the scoria has been carefully removed by calcination. It is a marvellous fact, that these mines, and these only, when they have been abandoned for some time, become replenished, and are more prolific than before. This would appear to be effected by the air, infusing itself at liberty through the open orifices, just as some women become more prolific after abortion. This was lately found to be the case with the Santarensian mine in Bætica;[1729] which, after being farmed at an annual rental of two hundred thousand denarii, and then abandoned, is now rented at two hundred and fifty-five thousand per annum. In the same manner, the Antonian mine in the same province has had the rent raised to four hundred thousand sesterces per annum.
It is a remarkable fact, that if we pour water into a vessel of lead, it will not melt; but that if we throw into the water a pebble or a copper quadrans,[1730] the vessel will be penetrated by the fire.
CHAP. 50. (18.)—FIFTEEN REMEDIES DERIVED FROM LEAD.
Lead is used in medicine, without any addition, for the removal of scars; if it is applied, too, in plates, to the region of the loins and kidneys, in consequence of its cold nature it will restrain the venereal passions, and put an end to libidinous dreams at night, attended with spontaneous emissions, and assuming all the form of a disease. The orator Calvus, it is said, effected a cure for himself by means of these plates, and so preserved his bodily energies for labour and study. The Emperor Nero—for so the gods willed it—could never sing to the full pitch of his voice, unless he had a plate of lead upon his chest; thus showing us one method of preserving the voice.[1731] For medicinal purposes the lead is melted in earthen vessels; a layer of finely powdered sulphur being placed beneath, very thin plates of lead are laid upon it, and are then covered with a mixture of sulphur and iron. While it is being melted, all the apertures in the vessel should be closed, otherwise a noxious vapour is discharged from the furnace, of a deadly nature, to dogs in particular. Indeed, the vapours from all metals destroy flies and gnats; and hence it is that in mines there are none of those annoyances.[1732] Some persons, during the process, mix lead-filings with the sulphur, while others substitute ceruse for sulphur. By washing, a preparation is made from lead, that is much employed in medicine: for this purpose, a leaden mortar, containing rain water, is beaten with a pestle of lead, until the water has assumed a thick consistency; which done, the water that floats on the surface is removed with a sponge, and the thicker part of the sediment is left to dry, and is then divided into tablets. Some persons triturate lead-filings in this way, and some mix with it lead ore, or else vinegar, wine, grease, or rose-leaves. Others, again, prefer triturating the lead in a stone mortar, one of Thebaic stone more particularly, with a pestle of lead; by which process a whiter preparation is obtained.
As to calcined lead, it is washed, like stibi[1733] and cadmia. Its action is astringent and repressive, and it is promotive of cicatrization. The same substance is also employed in preparations for the eyes, cases of procidence[1734] of those organs more particularly; also for filling up the cavities left by ulcers, and for removing excrescences and fissures of the anus, as well as hæmorrhoidal and condylomatous tumours. For all these purposes the lotion of lead is particularly useful; but for serpiginous or sordid ulcers it is the ashes of calcined lead that are used, these producing the same advantageous effects as ashes of burnt papyrus.[1735]