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Perrhæbeans, and many other Places; but theſe are of a peculiar Kind, and are rather of a ſtony, than of an earthy Texture.
CXII. The Stone from which Gypſum is made, by burning, is like [1]Alabaſter; it is not dug, however, in ſuch large Maſſes, but in ſeparate Lumps. Its Viſcidity and Heat, when moiſtened, are very wonderful.
- ↑ Pliny ſays, the Stones burnt to make Gypſum ought to be of the Marble or Alabaſter Kind; and that in Syria they choſe the hardeſt they can get; lib. 36. c. 24. Qui coquitur Lapis non diſſimilis Alabaſtritæ eſſe debet aut marmoroſo; in Syria duriſſimos ad id eligunt, &c. His Commentators ſay he took this from our Author; hæc ex Theophraſti, lib. Περὶ λίθων, Dal. If he did, he has been very careleſs in tranſlating him; a Fault I have been obliged
the beſt and fineſt in the World, is burnt to a proper State in about two Hours. Ours of Derbyſhire takes but little more Time, if properly managed; and that of Yorkſhire, which is generally redder and coarſer, a little more than that. We have no Opportunities of trying the Lapis Specularis of the Antients now; but by the general Conſent of the Writers of Antiquity, the Gypſum made of it exceeded all the other Kinds: The Subſtance itſelf from this obtained a Name, by which it became afterwards generally known, which was Gypſinum Metallum. The Want of knowing this, however, among the Commentators on ſome of the Works of the Writers ſince, has occaſioned much blundering; for finding Accounts, in the moſt expreſs Words, of Windows and Reflecting Mirrors, made of the Metallum Gypſinum; and not conceiving that this was only another Name for the Lapis Specularis, which it had obtained from being the Matter of which Gypſum was made, they made no Scruple of blotting out the Word Gypſinum, becauſe they did not underſtand it; a Thing too cuſtomary among this ſet of People; and ſupplied its Place with Cyprinum, leaving a Paſſge which they imagined very dark, much darker than they found it.
