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DE NATURA FOSSILIUM
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movement
of the quicksilver ceases. It is then heated over a very hot fire until
it gives off red fumes. It gives off yellow fumes first, then blue and
finally red. When the red fumes appear the vessel is removed from the
tripod or furnace and after it is cool, broken. Some do not mix the
sulphur and quicksilver in a shallow dish first but put them together
in the flask and produce the minium in a single operation. Some use equal parts of sulphur and quicksilver but this produces a very poor grade of minium when compared to that mentioned above. I shall describe vein minium that has a scarlet hue and minium secundarium in the next book.15
I
shall now mention the form of quicksilver the chemists call sublimate.
This is prepared in the following way. Equal parts of quicksilver and atramentum sutorium are
ground in a mortar with vinegar until all the quicksilver is taken up.
When dry the mixture is placed in an earthenware dish, covered with a
similar dish and sealed with mud. After heating for three hours it is
removed from the fire and cooled. Both liquid and solid are then
removed. The mixture is ground a second time in a mortar, sprinkled
with vinegar and heated again. This is repeated until all the
quicksilver has been driven to the cover by the heat and congealed.16 I shall take up the cadmia that the chemists call sublimate in the next book.
There are three kinds of psoricum. They are all made by mixing either two parts of chalcitis with one part of cadmia fornacum; two parts of chalcitis with one of foam of silver; or equal parts of chalcitis and cadmia. After
mixing the first and second varieties are ground with vinegar which is
added a drop at a time. The third variety is ground with wine. Later,
when the dog-star Sirius rises and everything is parched with the heat
of the sun, each is placed in an earthenware vessel, covered with dung
and left for forty days. Afterwards the mixtures are placed in a second
vessel and thoroughly dried over a charcoal fire until they turn red.
All psoricum dries and warms while that made with foam of
silver is the weakest. That made with wine does not bite as much as
that made with vinegar.17
Syricum, which is used by painters, is made by mixing sinopis1B with
15 At
first the mercury sulphide now called cinnabar was called minium. As
the alchemists worked with this and other materials it was discovered
that an oxide of lead could be produced with a red color almost
identical to that of minium. They started adulterating the more
valuable mercury sulphide with this artificial lead oxide until
eventually this red pigment contained no mercury sulphide and today the
name has come to be applied to the adulterant and the original material
is now given a new name, cinnabar. The method mentioned above that used
a coatÂing of lead oxide on the inside of the flask was one form of
adulteration.
16 This would probably be an impure hydrous basic mercury sulphate.
17 A mixture of lead oxide and ferric oxide.
18 The following reference to terra sinopis is found in Bermannus, page 462, Bermannus. "... Now you may mention anything you know concerning sinopis. Naevius. "Dioscorides, as you know, chose as sinopis ocher that which is dense,
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