What Painting Is: How to Think about Oil Painting ... - Victoria Vesna

178 WHAT PAINTING IS
is possible to see that as the silver floats through the light it is
transmuted miraculously into minuscule flakes of gold.
Another experiment is a recipe for the famous Mosaic gold
(aurum musivum), one of the mysterious gold-substitutes that the
alchemists devised. 4 To give the flavor of the old texts I
reproduce it here the way it might have been printed in an old
alchemical text—except that I have made it readable by spelling
out the names of the symbols. (In the original books, the symbols
stood alone and it was up to the neophyte to figure out what they
stood for.) It takes 2 days and requires tin powder ,
mercury , sulfur powder , and sal ammoniac , as well as
a breakable round-bottomed flask or crucible , a mortar and
pestle, and a towel and hammer. You begin by heating two parts
of in the , using a gentle flame . As soon as the has
melted fully, remove the heat, add one part of and stir the
mixture with a glass rod until it has cooled into a granular mass.
Grind this amalgam in a mortar with a little more than one
part of and one part of .
When a homogeneous has been obtained, place the mixture
into a glass flask with a round belly and a long neck, and heat it
gradually on a sand bath until white fumes and yellow
droplets arise into the neck of the flask.
Keep the heat constant at that degree (250–300° C) for three
hours , after which time the white and yellow colors will
have been replaced by black and red sublimate . Then
gradually increase the heat over the course of another until
the very bottom of the flask approaches a very dull red heat
(400–500° C). Turn off the heat, and allow to cool.
When it is cool, remove the flask from the and (having
wrapped it in a cloth) break the bulb of the with a hammer
blow. The mosaic gold rests as a hemispherical lump at the
bottom of the , often accompanied by a few fine black or grey
fuzzy particles which can be separated and discarded. A black
or very dark red ring of sublimed cinnabar (Vermilion) is
sometimes found in the throat. 5
This experiment results in a scintillating crystalline gold, with
speckles of red and green mixed in (COLOR PLATE 12).
According to modern chemistry, the “gold” is stannic sulfide,
SnS 2, but in alchemical terms it is almost more beautiful than
gold itself. It was exotic results like this that kept the alchemists
going: if three of the most basic ingredients of alchemical work—