CHAP. 43.—TOUCHSTONES FOR TESTING GOLD.
A description of gold and silver is necessarily accompanied
by that of the stone known as "coticula." [Note] In former times,
according to Theophrastus, this stone was nowhere to be
found, except in the river Tmolus, [Note] but at the present day it is
found in numerous places. By some persons it is known as
the "Heraclian," and by others as the "Lydian" stone. It
is found in pieces of moderate size, and never exceeding four
inches in length by two in breadth. The side that has lain
facing the sun is superior [Note] to that which has lain next to the
ground. Persons of experience in these matters, when they
have scraped a particle off the ore with this stone, as with a
file, can tell in a moment the proportion of gold there is in it,
how much silver, or how much copper; and this to a scruple,
their accuracy being so marvellous that they are never mistaken.
