The
"nitron" of the Greeks referred to the natural deposits of alkaline
salts from various sources. The uses to which it was put shows it to
have been essentially sodium carbonate so that the term natron as used
here is not thought inappropriate as an inclusive term for all such
alkaline deposits. Cimolian earth was perhaps a kind of a clay.
13. Another (Recipe).
First
take and etch the pearls in the urine of an uncorrupted youth; coat
them with alum, and let dry on them what remains of the corrosive. Then
take and put mercury and fresh bitch's milk into a clay vessel, heat
all together and in doing so regulate what takes place. Use only
foreign coals and a gentle fire.
14. Preparation of Carnelian.
Dissolve
alkanet in oil. After that, put in the blood of a pigeon, and fine
Sinopian earth and a little vinegar in order that the blood does not
coagulate. Place selenite in it, close the vessel and place it amidst
the dew for ten days. If you wish to make the stone very brilliant,
arrange it so as to wrap it in horse hair, tie this on, and put it in
the dye bath.
It
is not certain whether what we term as selenite was used here, but at
any rate it was some kind of a transparent stone capable of absorbing
color, and it appears very probable that our selenite was used.
15. Preparation of Lapis Lazuli.
The
lapis lazuli employed is first dipped in the bile of a tortoise and
then placed in the dye bath for amethyst for just as many days as for
this and so forth.
16. Purification of Crystal.
The
purification of a smoky crystal. Put it in a willow basket, place the
basket in the boiler of the bath and leave the crystal there 7 days.
Take it out when it is purified, and mix warm lime with vinegar. Stick
the stone therein and let it be etched. Finally, color it as you wish.
17. Preparation of Emerald.
Take
and put so-called topaz stone in liquid alum and leave it there 3 days.
Then remove it from this and put it in a small copper vessel in which
you have placed pure unadulterated verdigris along with sharp vinegar.
Put the cover upon the vessel, close up the cover, and gently keep a
fire under the vessel with olive wood for 6 hours, otherwise the longer
you maintain the fire, the better and deeper will the stone be—only,
as I say, with a gentle fire. Cool and lift the stone out. Its
condition will show whether it has become emerald. That is to say, you
will observe that a green film has formed upon it. Let it become slowly
cooled, however; if not, it soon breaks. Put oil in a small box-tree
vessel many days beforehand so that the oil is purified and the
product from it can be taken off. Put in the stone and leave it under
cover 7 days. On taking out you will have an emerald which resembles
the natural ones.
18. Manufacture of a Pearl.
Take
and grind an easily pulverized stone such as window mica. Take gum
tragacanth and let it soften for ten days in cow's milk. When it has
become soft, dissolve it until it becomes as thick as glue. Melt Tyrian
wax; add to this, in addition, the white of egg. The mercury should
amount to 2 parts and the stone 3 parts, but all remaining substances 1
part apiece. Mix (the ground mica and the molten wax) and knead the
mixture with mercury. Soften the paste in the gum solution and the
contents of the hen's egg. Mix all of the liquids in this way with the
paste. Then make the pearl that you intend to, according to a pattern.
The paste very shortly turns to stone. Make deep round impressions and
bore through it while it is moist. Let the pearl thus solidify and
polish it highly. If managed properly it will excell the natural.
