Aquafortis for parting[198] is made thus. You take 8 lbs. of burnt
rock alum[199] & an equal quantity of the best saltpetre, and 4
lbs. of Roman vitriol, & put them altogether into the alembic,[200]
add to these things a little aquafortis that has already been used,
exercising your discretion as to the quantity. And in order to give
a good luting[201] to your alembic take horse-dung, iron filings &
brick dust in equal proportions, and mix them up with the yolk of
a hen’s egg, then smear the mixture over the alembic as far as the
furnace will allow. Then for the rest put it to a moderate fire, as
the wont is.
FOOTNOTES:
[198] _Partire._
[199] _Allume di rôcca arso._ _Prof. Church tells me that this is
probably sulphate of alumina, from alum shale._
[200] _Boccia._ _Biringoccio in the fourth book of his
‘Pirotechnica,’ Venice, 1540, Chap. I., gives an illustrated
description both of such an alembic and of how aquafortis for parting
is distilled. See also the French edition of the same book translated
by ‘Jaques Vincent.’ Rouen, 1627._
[201] _Loto_: _the closing of the joints_.