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Book IX artificially coloring of metals such as gold, silver, copper

Book IX artificially coloring of metals such as gold, silver, copper Page of 251 Book IX artificially coloring of metals such as gold, silver, copper Text size:minus plus Restore normal size   Mail page  Print this page
200
DE NATURA FOSSILIUM
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 coat­ing 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,
Book IX artificially coloring of metals such as gold, silver, copper Page of 251 Book IX artificially coloring of metals such as gold, silver, copper
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