CHAPTER XXXVI. HOW TO MAKE ROYAL CEMENT.
Take the gold you wish to refine and beat it thin, cut it into little pieces of the size and the thickness of a golden scudo. Sometimes the scudi themselves are taken and a twenty-four carat cement refined direct from them; and this simple[202]cement has such virtue that it can draw all the alloy[203]out of the scudo itself without destroying the impression on the coin, but drawing from it only what was of base metal.
The cement is made in this wise: Take tartar and brick dust and make a paste of them; construct a round furnace[204], & into the joints of the furnace between one brick and another spread the paste; put your pieces of gold, or the scudi themselves, if you use them, into the paste, and cover them well up with more of it; then fire for twenty-four hours, at the end of which time they will be refined to twenty-four carats.[205]
Know, gentle reader, that this screed of mine is not writ for the purpose of teaching such as are refiners[206]by profession how to make aquafortis, my only care is to show how & to what end it may serve the art of goldsmithing; for it came about that having made certain golden figures half a cubit high for King Francis, when they were near the ending, during the softening in the fire, it happened they got a film of lead fumes across them, and had I not covered them over with this cement lotion they would have gone brittle as glass.[207]Then I gave them six hours moderate firing, and so in this way freed them from so evil a blemish.
THE END OF THE TREATISE ON GOLDSMITHING.
FOOTNOTES:[202]Cellini may intend a stronger sense to the word‘semplice.’[203]Lega.[204]See above, furnace construction.[205]Cellini appears not to have quite understood the process. Geber, who gives the oldest description of it, ‘Alchemiae Gebri Arabis Philosophi Solertissimi Libri, etc. Joa͠n: Petreius Nuremberge͠n denuo Bernae excudi faciebat,’anno 1545, p. 51, gives the ingredients thus: ‘Vitriol (ferrous sulphate), sal ammoniac, flower of copper (scale of oxide of copper formed by heating the metal with access of air), ground oldearthenpot, sulphur in the smallest quantity or none at all, man’s urine, together with similar sharp and penetrating substances,’ etc. See Percy’s ‘Metallurgy,’ Murray, 1880; Part I., p. 385. Prof. Roberts-Austen adds that ‘usually the “cement,” and the gold to be purified, were placed together into a porous earthen pot, and not between the joints of the brickwork.’[206]Partitore.[207]I am assured that this is a point of considerable scientific interest.
[202]Cellini may intend a stronger sense to the word‘semplice.’
[202]Cellini may intend a stronger sense to the word‘semplice.’
[203]Lega.
[203]Lega.
[204]See above, furnace construction.
[204]See above, furnace construction.
[205]Cellini appears not to have quite understood the process. Geber, who gives the oldest description of it, ‘Alchemiae Gebri Arabis Philosophi Solertissimi Libri, etc. Joa͠n: Petreius Nuremberge͠n denuo Bernae excudi faciebat,’anno 1545, p. 51, gives the ingredients thus: ‘Vitriol (ferrous sulphate), sal ammoniac, flower of copper (scale of oxide of copper formed by heating the metal with access of air), ground oldearthenpot, sulphur in the smallest quantity or none at all, man’s urine, together with similar sharp and penetrating substances,’ etc. See Percy’s ‘Metallurgy,’ Murray, 1880; Part I., p. 385. Prof. Roberts-Austen adds that ‘usually the “cement,” and the gold to be purified, were placed together into a porous earthen pot, and not between the joints of the brickwork.’
[205]Cellini appears not to have quite understood the process. Geber, who gives the oldest description of it, ‘Alchemiae Gebri Arabis Philosophi Solertissimi Libri, etc. Joa͠n: Petreius Nuremberge͠n denuo Bernae excudi faciebat,’anno 1545, p. 51, gives the ingredients thus: ‘Vitriol (ferrous sulphate), sal ammoniac, flower of copper (scale of oxide of copper formed by heating the metal with access of air), ground oldearthenpot, sulphur in the smallest quantity or none at all, man’s urine, together with similar sharp and penetrating substances,’ etc. See Percy’s ‘Metallurgy,’ Murray, 1880; Part I., p. 385. Prof. Roberts-Austen adds that ‘usually the “cement,” and the gold to be purified, were placed together into a porous earthen pot, and not between the joints of the brickwork.’
[206]Partitore.
[206]Partitore.
[207]I am assured that this is a point of considerable scientific interest.
[207]I am assured that this is a point of considerable scientific interest.