BOOK XII.

58i

A — Long wall. B—High walls. C—Low walls. D— Plates. E— Upper pots.

F— Lower pots.

g B

sS%tl§':

mmm

The sulphur from such a mixture can best be extracted if the upper pots areplaced in a vaulted furnace, like those which I described among othermetallurgical subjects in Book VIII., which has no floor, but a grate inside;under this the lower pots are placed in the same manner, but the platesmust have larger holes.

Others bury a pot in the ground, and place over it another pot with ahole at the bottom, in which pyrites or cadmia, or other sulphurous stonesare so enclosed that the sulphur cannot exhale. A fierce fire heats thesulphur, and it drips away and flows down into the lower pot, which cont ainswater. (Illustration p. 582).

Bitumen 14 is made from bituminous waters, from liquid bitumen, andfrom mixtures of bituminous substances. The water, bituminous as well as

14 The substances referred to under the names bitumen, asphalt, maltha, naphtha,petroleum, rock-oil, etc., have been known and used from most ancient times, and much of ourmodern nomenclature is of actual Greek and Roman ancestry. These peoples distinguishedthree related substances,—the Greek asphaltos and Roman bitumen for the hard material,—Greek pissasphaltos and Roman maltha for the viscous, pitchy variety—and occasionally theGreek naphtha and Roman naphtha for petroleum proper, although it is often enough referredto as liquid bitumen or liquid asphaltos. The term petroleum apparently first appears inAgricola’s De Natura Fossilium (p. 222), where he says the “ oil of bitumen . . . now