^ On the Antiquity of Etching on Qlajs. 3 



receipt for that purpofe was made public, for the firft time, in January, 1725*, by the before 

 mentioned M. Pauli. How he came to know it, I have not been able to learn. 



That the inventor employed his corrofive to a purpofe different from that for which it is 

 ufed at prefent, is obvious from the effcdl it produced upon the glafs. At prefent the glafs. 

 is covered either with wax, ifinglafs, or a varnilh, and thofe figures which are intended to 

 be etched, are traced through this covering, by means of a pointed inftrument; but our 

 ancient artift covered his figures, when traced, with a varnifli and fulphur, and then applied 

 the acid to corrode the glafs around them, fo that the figures which remained fmooth and 

 clear appeared, when the varnifli was removed, as if raifed from a dim or dark ground. He 

 adopted this method probably in order to render his invention more palpably different from 

 the art of cutting the figures on the glafs, as if engraven, long known and praftifed before 

 this difcovery was made. 



That the Bohemian emerald, or hefphorus, made ufe of in this receipt, was our fluate of 

 lime, can hardly be doubted. In old German authors who treat on the working of mines, 

 this ftone is claffed amongft the fluffe (fluxes) becaufe it was an ufual fubftitute to accelerate 

 the fufion of certain ores. Agrico/a, who changed the German names of quartz, zinc, 

 bifmuth, cobald, &c. into quartzum, zincum, &c. changed flufs into fluor, which became 

 afterwards very common +. If a paffage of the ancients can be quoted that feems to allude 

 to fluate of lime, it is that of Theophraftus, where he fays, that there are certain ftones 

 which, when added to filver, copper, and iron ores, become fluid. For Cronftadt was the 

 firft fyllematic writer (if I am not miftaken) who mentioned fluate of lime as a particular 

 genus. 



That the ftone called emerald, or hefphorus, was really our fluor fpar, becomes obvious 

 from what Kirchmair, profeffor at Wittemberg, in Germany, remarks, who was probably 

 the firft who made known what kind of ftone it was, which had the peculiar property of 

 fhining in the dark after having been heated f, and which by tlie ancients was fought for 



* Breflawei's Colleftions, 1. c. 



f Lapides funt gemmarura fimiles, fed minus duri, fluores liceat mihi verbum an e verbo exprimere, 

 noftri raetalllci appellant, nee meo judicio, inepte; fiquidem ignis calore, ut glacies iblis, liquefcuut et 

 fluunt. Varii autemet jucundi colores eis infident. 



Bergmannii Opuscul, p. 4.66. 



% Ante annos pacuos admodum invefttus mineralis alicujus vifu et propiietatibus in quibufdam firailis 

 fmaragdo, ab artificibus duobus miUi per amice notis ufus eft. Conficiendi phofphori et repraefentandi 

 modus ievls atque brevis ille. Recipe q. v. mineralis viridis fmaragdum pene referentis; contare in 

 pulverem, aqua madefac communi, pulvis inftar ut fiat. Pencillo psftea in lamina cuprea, magnitudine 

 Yel majoris plan! alicujus manubrio inftrufta literas, quafcunque voles, in lamina defciibe cralTIufculas, 

 Ardentibus fuper impone prunis vafculo exceptis. Phoenomenon fpe£labis in obfcuro amseniffimum fine 

 fume et odore lucens. Sed ut verum fatear, nee ufum, nifi curiofi animi explendi, artificium hoc, neque 

 diuturnitatem habet. Peflus ergo avidum fcieudi meliora fatiari nequit Cvfe Hefph«rus vocetur five 

 Vefperugo. 



G. C. Kirchmaieri De Phofphoris at natura lucis, nee noB de igne, commentatio epiHoIica. Wittem- 

 btrgae, 16S0, p. 7. 



B 2 with 



