A—TUNNEL. B—BUCKET. C—PIT.
In hot regions or in summer, it is poured into out-of-door pits which have
been dug to a certain depth, or else it is extracted from shafts by pumps
and poured into launders, through which it flows into the pits, where it is
condensed by the heat of the sun. In cold regions and in winter these vitriol
waters are boiled down with equal parts of fresh water in rectangular leaden
caldrons; then, when cold, the mixture is poured into vats or into tanks,
which Pliny calls wooden fish-tanks. In these tanks light cross-beams are
fixed to the upper part, so that they may be stationary, and from them hang
ropes stretched with little stones; to these the contents of the thickened
solutions congeal and adhere in transparent cubes or seeds of vitriol, like
bunches of grapes.
In hot regions or in summer, it is poured into out-of-door pits which have
been dug to a certain depth, or else it is extracted from shafts by pumps
and poured into launders, through which it flows into the pits, where it is
condensed by the heat of the sun. In cold regions and in winter these vitriol
waters are boiled down with equal parts of fresh water in rectangular leaden
caldrons; then, when cold, the mixture is poured into vats or into tanks,
which Pliny calls wooden fish-tanks. In these tanks light cross-beams are
fixed to the upper part, so that they may be stationary, and from them hang
ropes stretched with little stones; to these the contents of the thickened
solutions congeal and adhere in transparent cubes or seeds of vitriol, like
bunches of grapes.