Page 242 - Copper and Bronze in Art: Corrosion, Colorants, Getty Museum Conservation, By David Scott

Northern salt, gum ammoniac, ibex grease, honey, frankincense, celery, calamine (?), onion,
hammering-flakes from copper, grease of sheep, cumin, oil and natron are ground and it is
bandaged therewith. 2
The small amount of copper ions needed for treatment could have been supplied by either cop­
per or copper sulfides. In a recipe to remedy an injury to the eyes, Pliny states that "stibium,
malachite, red ochre, sory and honey are applied to the eye-lids." Sory has been identified by
3
Knoll and colleagues (i985) as referring to the copper sulfides, although other authors regard it
as probably a basic copper sulfate (see CHAPTER 4). Sugars and other organic ingredients in the
honey probably produced copper salts in the mixture. One of the advantages of the copper sul­
fides in medicinal recipes is that their low solubility in aqueous solution allows control over the
amount of copper delivered by the ointment or preparation.
The synthesis of copper sulfides for another medicinal was also recorded by Pliny in the fol­
lowing passage:

Taken with honey it also acts as an emetic, but for this Cyprian copper with an equal weight
of sulphur is roasted in pots of unbaked earthenware, the mouth of the vessels being stopped
with oil; and then left in the furnace till the vessels themselves are completely baked. 4

The Mappae clavicula, a medieval Latin manuscript containing recipes from the Classical
world (Smith and Hawthorne 1974), includes a recipe by Dioscorides for the synthesis of a cop­
per sulfide. The instructions given are similar to those in the Indian recipe from Dutta quoted
earlier. Dioscorides' recipe 139 states that

copper calcine is made in this way. Make leaves out of very clean copper and put these
leaves in an unused pot with some ground natural sulphur; and spread out the leaves
in a cooking-pot; then sprinkle sulphur on top, and again put leaves and sprinkle sul­
phur; do so repfeatedly until you have filled the pot. Then, place the pot in a glasswork-
er's furnace, and cook for 3 days and when it has cooled, break it up very small. (Smith and
Hawthorne 1974:12)

If the pot were well sealed, the product would certainly be a copper sulfide, or a mixture of cop­
per sulfides, depending on the conditions of the reaction and the temperatures reached.
A number of historical records describe the action of sulfur on copper and the formation of
sulfides, including observations by Geber in his Summa perfectionis magisterii (The Sum of Per­
5
fection, or the Perfect Magistery), written in the fourteenth century (Mellor 1928), and those of
the German philosopher and theologian Albertus Magnus (1200-1280), who studied the reac­
tion of sulfur with a variety of metals. It took some time, however, before the diversity of these
copper sulfides was fully appreciated.

C O P P E R S U L F I D E S
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