BOOK IX.

427

with moss, are placed upside down in the openings of the lower pots, where theyare joined with lute, lest the quicksilver which takes refuge in them shouldbe exhaled. There are some who, after the pots have been buried, do not fearto leave them uncemented, and who boast that they are able to produce noless weight of quicksilver than those who do cement them, but neverthelesscementing with lute is the greatest protection against exhalation. In thismanner seven hundred pairs of pots are set together in the ground or on ahearth. They must be surrounded on all sides with a mixture consisting ofcrushed earth and charcoal, in such a way that the upper pots protrude to aheight of a palm above it. On both sides of the hearth rocks are first laid,and upon them poles, across which the workmen place other poles transversely ;these poles do not touch the pots, nevertheless the fire heats the quick-silver, which fleeing from the heat is forced to run down through the mossinto the lower pots. If the ore is being reduced in the upper pots, it fleesfrom them, wherever there is an exit, into the lower pots, but if the ore onthe contrary is put in the lower pots the quicksilver rises into the upper potor into the operculum, which, together with the gourd-shaped vessels, arecemented to the upper pots.

A Hearth. B—Poles. C —Hearth without fire in which the pots are placed.R Rocks. E — Rows of pots. F —Upper pots. G —Lower pots.

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