1generally is; I have written elsewhere of its
nature38.
First the gold is
rubbed on the touchstone, whether it contains silver or whether it is obtained
from the mines or from the smelting; silver also is rubbed in the same
way. Then one of the needles, that we judge by its colour to be of similar
composition, is rubbed on the touchstone; if this proves too pale, another
needle which has a stronger colour is rubbed on the touchstone; and if this
proves too deep in colour, a third which has a little paler colour is used. For
this will show us how great a proportion of silver or copper, or silver and
copper together, is in the gold, or else how great a proportion of copper is in
silver.
rubbed on the touchstone, whether it contains silver or whether it is obtained
from the mines or from the smelting; silver also is rubbed in the same
way. Then one of the needles, that we judge by its colour to be of similar
composition, is rubbed on the touchstone; if this proves too pale, another
needle which has a stronger colour is rubbed on the touchstone; and if this
proves too deep in colour, a third which has a little paler colour is used. For
this will show us how great a proportion of silver or copper, or silver and
copper together, is in the gold, or else how great a proportion of copper is in
silver.
These needles are of four kinds.39
The first kind are made of gold and
silver, the second of gold and copper, the third of gold, silver, and copper,
and the fourth of silver and copper. The first three kinds of needles are
used principally for testing gold, and the fourth for silver. Needles of this
kind are prepared in the following ways. The lesser weights correspond
proportionately to the larger weights, and both of them are used, not
only by mining people, but by coiners also. The needles are made in
accordance with the lesser weights, and each set corresponds to a bes,
which, in our own vocabulary, is called a mark. The bes, which is employed
by those who coin gold, is divided into twenty-four double sextulae, which
silver, the second of gold and copper, the third of gold, silver, and copper,
and the fourth of silver and copper. The first three kinds of needles are
used principally for testing gold, and the fourth for silver. Needles of this
kind are prepared in the following ways. The lesser weights correspond
proportionately to the larger weights, and both of them are used, not
only by mining people, but by coiners also. The needles are made in
accordance with the lesser weights, and each set corresponds to a bes,
which, in our own vocabulary, is called a mark. The bes, which is employed
by those who coin gold, is divided into twenty-four double sextulae, which
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