which issued a noxious vapour, which more than once extinguished the
candles. Since the destruction of the building many subterraneous cells
have been discovered under a piece of ground, which seemed only a bank
of solid earth before the horrid secrets of this prison-house were
disclosed. Some skeletons were found in these recesses with irons still
fastened to their decayed bones." Letters from France, by H.M. Williams,
p. 24.]


395 VII. "GNOMES! YOU then taught volcanic airs to force
Through bubbling Lavas their resistless course,
O'er the broad walls of rifted Granite climb,
And pierce the rent roof of incumbent Lime,
Round sparry caves metallic lustres fling,
400 And bear phlogiston on their tepid wing.


[_And pierce the rent roof_. l. 398. The granite rocks and the limestone
rocks have been cracked to very great depths at the time they were
raised up by subterranean fires; in these cracks are found most of the
metallic ores, except iron and perhaps manganese, the former of which is
generally found in horizontal strata, and the latter generally near the
surface of the earth.

Philosophers possessing so convenient a test for the discovery of iron
by the magnet, have long since found it in all vegetable and animal
matters; and of late Mr. Scheele has discovered the existence of
manganese in vegetable ashes. Scheele, 56 mem. Stock. 1774. Kirwan. Min.
353. Which accounts for the production of it near the surface of earth,
and thence for its calciform appearance, or union with vital air.