Craft Recipes: Parting Gold from Silver, Gilding, and Yellow Glass
Crucible work with aqua fortis, tinting gold-work, and coloring glass
A close-written page collects metalworking and craft recipes, headed by a method for refining gold from silver in a crucible, casting it into a bar, beating it thin and separating the metals in parting-water so the gold sinks and the silver dissolves. Several formulas for aqua fortis follow, using vitriol, saltpetre and rock-alum, along with mixtures of verdigris and sal ammoniac for tinting gold-work. Further recipes give a yellow glass made from tuzia, turmeric and borax laid in a crucible between a paste of bean-flour, figs, raisins and honey, and a last aqua fortis that "dissolves the sun." Faint construction lines are also visible at the lower left.
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Parting gold from silver in the crucible
The metal is melted in a covered crucible over a slow fire, cast into a bar and beaten thin, then separated in parting-water so that the gold falls to the bottom and the silver stays in solution, the twelfth part that was added coming out as fine gold. The silver is then recovered from the water at a gentle fire and recast into a bar for the next round.
Recipes for aqua fortis and for tinting gold-work
One aqua fortis takes a pound each of vitriol, saltpetre and rock-alum; another, a pound each of saltpetre and rock-alum. For tinting finished gold-work, vitriol, verdigris and saltpetre are placed in the crucible with the gold to be tinted, a fuller version adding sal ammoniac and virgin wax.
Recipe for yellow glass
Yellow glass is made from an ounce of tuzia, three quarters of turmeric and a quarter of borax, powdered together, then laid in a crucible between a paste of bean-flour, dried fat figs, raisins and honey, with the glass set on the paste and the fire raised until it melts. A final aqua fortis of sal ammoniac, red copper and saltpetre in equal parts is noted to "dissolve the sun."