There is another product of these furnaces, which is easily
distinguished from smegma, and which the Greeks call "diphryx,"1
from its being twice calcined. This substance is prepared
from three different sources. It is prepared, they say,
from a mineral pyrites, which is heated in the furnace until
it is converted by calcination into a red earth. It is also
made in Cyprus, from a slimy substance extracted from a certain
cavern there, which is first dried and then gradually heated,
by a fire made of twigs. A third way of making it, is from
the residue in the copper-furnaces that falls to the bottom.
The difference between the component parts of the ore is this;
the copper itself runs into the receivers, the scoriæ make their
escape from the furnace, the flower becomes sublimated, and
the diphryx remains behind.
Some say that there are certain globules in the ore, while
being smelted, which become soldered together; and that the
rest of the metal is fused around it, the mass itself not becoming
liquefied, unless it is transferred to another furnace, and forming
a sort of knot, as it were, in the metal. That which remains
after the fusion, they say, is called "diphryx." Its use in medicine
is similar to that of the substances mentioned above;2
is desiccative, removes morbid excrescenses, and acts as a detergent.
It is tested by placing it on the tongue, which ought to
be instantly parched by it, a coppery flavour being perceptible.