68. Corrosion of Crystal.
A
special corrosion of crystal. It is put in sulphur, quicklime, and alum
together with vinegar, three or four times. However, leave it to absorb
therefrom 3 or 4 days and then apply the following recipe.
69. Corrosion of All Kinds of Stones.
The
plant heliotrope, which produces clusters, serves for the general
opening up and corrosion of every stone. Extract the juice from it,
open up the stones therein, and you will have good luck with the
coloring of every stone.
70. The Kinds of Stones to Color.
The
suitable stones for coloring are crystal and topaz. Pyrites has the
tendency to become gradually red. Boil (the stones), however, whilst
you exclude everything, in a small protected house which stands
opposite to any adverse 'wind.
The
pyrites mentioned here is certainly not the mineral that we call by
that name. Great uncertainty exists as to just what the Ancients did
mean by their term pyrites. Compare Pliny, Book XXXVII, 189, and Book
XXXVI, 137, with Dioscorides V, 84, to see the confusion concerning
this word.
71. Preparation of Emerald.
Mix
copper green, the urine of a boy, and calves' bile in a new pot. Lute
the cover with clay, but previously put the crystals in the pot, and
cook it for 5 hours with a gentle fire of olive wood. You will suddenly
see by the cover when it is to be heated no more. Cool and take them
out. The cover of the pot should, however, be unbaked.
72. Another (Preparation).
Preparation
for another rough emerald. Stick the stone in natron for 5 days. Then
stick it in a lump of ground "garlic" for 7 days. But after the lapse
of this time draw the juice from a leek and mix along with it an equal
quantity of oil. Put this in a new pot and boil it 3 days until the
stones absorb it. The cover should be unbaked.
73. Another (Recipe).
Rub
with vinegar: 1 part of very fine verdigris; an equal amount of alum;
roasted copper, a quantity equal to both the other materials; and bring
it to a pasty thickness. Put the small stones therein and let them be
baked for 7 days.
74. Preparation of Verdigris for Emerald.
Clean
a well-made sheet of Cyprian copper by means of pumice stone and water,
dry, and smear it very lightly with a very little oil. Spread it out
and tie a cord around it. Then hang it in cask with sharp vinegar so
that it does not touch the vinegar, and carefully close the cask so
that no evaporation takes place. Now if you put it in in the morning,
then scrape off the verdigris carefully in the evening, but if you put
it in in the evening, then scrape it off in the morning, and suspend it
again until the sheet becomes used up. However, as often as you scrape
it off again smear the sheet with oil as explained previously. The
vinegar is (thus rendered) unfit for use.
75. Preparation of Beryl.
Tie
crystal around with a hair and hang it in a pot along with the urine of
a she-ass for 3 days, but the crystal is not permitted to touch the
urine. The pot should be closed, however. Then place the pot over a
gentle fire and you will find a very good beryl.
76. Preparation of Emerald.
Take
pure pyrites or rock crystal and make the composition in the following
way: Verdigris, 2 drachmas; celandine, 1 drachma; Scythian black, 3
drachmas; liquid resin,
