728.
OF TAKING CASTS OF MEDALS.
A paste of emery mixed with aqua vitae, or iron filings with
vinegar, or ashes of walnut leaves, or ashes of straw very finely
powdered.
[Footnote: The meaning of _scagliuolo_ in this passage is doubtful.]
The diameter is given in the lead enclosed; it is beaten with a
hammer and several times extended; the lead is folded and kept
wrapped up in parchment so that the powder may not be spilt; then
melt the lead, and the powder will be on the top of the melted lead,
which must then be rubbed between two plates of steel till it is
thoroughly pulverised; then wash it with aqua fortis, and the
blackness of the iron will be dissolved leaving the powder clean.
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