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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
BOOK IX
193
the flame comes out and since it has been completely burnt it has the same lightness as glowing ashes. The foregoing is a description of the cadmia produced from copper ores or from pyrite that contains silver and the plumbum metals. The cadmia found in gold and silver furnaces is usually whiter and lighter since they are cleaned more often.
All cadmia produced in furnaces dries and is moderately astringent. If it is washed first it will not cause pain. That obtained from gold, silver, and plumbum ores is less efficacious than that from copper ores.
Pompholyx, after cadmia, adheres to the upper Avails of furnaces and is associated with the latter. It is the ash of either copper or cadmia fornacum or both. It forms when copper is smelted from cakes of the roasted ores or when, having been parted from silver, it is refined in a copper furnace. It is here that the ash is carried to the upper part of the furnace where it adheres to the walls and back. It first collects in small balls like drops of water and then swells, whence the name. It grows by addition of other material until it has the appearance of a woolen brush. It forms spon­taneously in a furnace. When the copper is smelted from roasted ore the pompholyx is sometimes of a copper color and when the copper is refined, of a grayish white color, both being somewhat unctuous. That obtained from the pyrite from Goslar is white.
By exercising care and diligence furnace workers produce pompholyx from cadmia in three ways. First, by sprinkling cadmia fornacum on cop­per that is being refined. Pure pompholyx is produced when alternate layers of copper and native cadmia (cadmia fossilis) are put in retorts to make brass. The ash of the molten copper is carried up to the hollow in the cover of the retort. If there is no cover on the retort this ash together with the ash of the burning wood is carried upward and adheres to the Avails of the furnace producing spodos. A third method is to heat furnace cadmia with a bellows until it glows. By these methods first quality ma­terial is obtained, that is, the whitest and lightest. Today furnace workers produce it by another method and at one time it was produced by two other methods that Dioscorides describes in a manuscript. All three meth­ods produce a white and light material but the one used today produces the whitest.
According to Galen the most tenuous portion of pompholyx, after being washed, is the best remedy known to stop the bite of pain. For that reason it is used on malignant ulcers and tumors. It is added to eye salves to stop watering of the eyes and to cure ulcers of the eyes as well as the pustules the Greeks call φλύκταινα (phyctena). It is also used to cure ulcers of the rectum.
Spodos, that some understand to mean ash, does not differ from pom­pholyx in origin since both are ashes that are produced in the same way although they are different genera. Pompholyx is white and light, spodos, gray and heavy. Some of it adheres to the outside of a furnace while some falls into the lowest part. It is scraped from the walls and swept into
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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