ions that this dark
alumen was used for purifying gold. He must be referring here to its
quality of giving gold a rich color. The liquid of this iron alumen,
if put upon light-colored gold, and heated over a fire, gives it a
very rich tint; a process practiced still for the same purpose. So
far, however, as the application to dyeing is concerned, it is
unnecessary to prove that the ancients used our double salt alum.
Probably the alumen referred to by Pliny, as exuding from the earth,
was sulphate of alumina, without potash or soda, a salt not easily
crystallized, but as effective, in many cases more effective, in the
operations of dyeing, as alum, which is attested by the preference
given to this salt over alum for many purposes at the present day.
Pliny says that alumen was a product of Spain, Egypt, Armenia,
Macedonia, Pontus, Africa, and the Islands of Sardinia, Melos, Lipara,
and Strangyle, and that the most esteemed is that of Egypt. And
Herodotus mentions that King Amasis of Egypt sent the people of Delphi
a thousand talents of this substance, as his contribution toward the
rebuilding of their temple. Notwithstanding considerable confusion in
Pliny's account of this substance, our belief is, that it refers to
different salts of alumina, and whether or not they were all used in
the processes of dyeing, they were used for manufacturing purposes,
and thus gives us some insight to the advanced state of the arts in
those times.

Respecting the cost and durability of the Tyrian purple, it is related
that Alexander the Great found in the treasury of the Persian monarch
5,000 quintals of Hermione purple of great beauty, and 180 years old,
and that it was worth $125 of our money per pound weight. The price of
dyeing a pound of wool in the time of Augustus is given by Pliny, and
this price is equal to about $160 of our money. It is probable that
his remarks refer to some particular tint or quality of color easily
distinguished, although not at all clearly defined by Pliny. He
mentions a sort of purple, or hyacinth, which was worth, in the time
of Julius Caesar, 100 denarii (about $15 of our money) per pound.

Since, according to our modern researches into this dye, one fish, the
common _Purpura lapillus_, produces only about one drop of the liquor,
then it would take about 10,000 fish to dye 1 lb. of wool, so that
$160 is not extravagant.

Spinning and weaving in ancient times were principally performed by
women; indee