[204] Mariette, Traité des Pierres gravées. Par. 1750, fol.
[205] The two ancient glasses found at Nismes, and described in Caylus’
Recueil d’Antiquités, ii. p. 363, were probably of this sort.
[206] Natter, Traité de la Méthode antique de graver en Pierres fines,
comparé avec la Méthode moderne. Lond. 1754, fol.
[207] Of this kind were the _calices audaces_ of Martial, xiv. 94, and
those cups which often broke when the artist wished to give them the
finishing touch.
[208] See Sandrart’s Teutsche Akademie, vol. i. part 2, p. 345, where
there is much valuable information respecting the German artists.
Compare also Doppelmayer’s Nachricht von Nürnberg. Künstlern.
[209] Oculus Artificial. iii. p. 79.
[210] Lib. xxxvii.
[211] Cap. 52, p. 59.
[212] Origin. xvi. 8.
[213] De Miner. lib. ii. 2.
[214] Traité des Pierres gravées, i. pp. 90, 156.
[215] Ibid. p. 156.
[216] In the preface, p. 15.
[217] Ueber den Nutzen d. geschnitt. Steine. Altenb. 1768, p. 42.
[218] Le Veil, iii. p. 19. This anecdote however is not mentioned by
Mezeray, Castelnau, or Laboureur; and Bayle must have been unacquainted
with it, or he would have introduced it into his long article on the
Duchesse d’Estampes.
[219] Doppelmayer, p. 232.
[220] Abhandlungen der Schwed. Akad. xxxiii. p. 122.
[221] Halle, Fortgesetzte Magie. Berlin, 1788, 8vo, i. p. 516. This
author says that the invention came from England, where it was kept
very secret; but the honour of the second invention belongs to H.
Klaproth.
[222] Schwanhard, by the acuteness of his genius, proved what was
before considered as impossible, and found out a corrosive so powerful
that the hardest crystal glass, which had hitherto withstood the force
of the strongest spirits, was obliged to yield to it, as well as
metals and stones. By these means he delineated and etched on glass,
figures of men, some naked and some dressed, and all kinds of animals,
flowers, and plants, in a manner perfectly natural; and brought them
into the highest estimation.--Sandrart, Teutsche Akademie, i. 2, p.
346.--Doppelmayer, p. 250, says, “After 1670 he accidentally found out
by the glass of his spectacles, upon which some aquafortis had fallen,
becoming quite soft, the art of etching on glass.”
[223] Breslauer Sammlung zur Natur- und Medicin-Geschichte. 1725,
January, p. 107. “Invention of a powerful acid by which figures of
every kind, according to fancy, can be etched upon glass.--When
_spiritus nitri per distillationem_ has passed into the recipient,
ply it with a strong fire, and when well dephlegmated, pour it, as it
corrodes ordinary glass, into a Waldenburg flask; then throw into it a
pulverised green Bohemian emerald, otherwise called _hesphorus_ (which,
when reduced to powder and heated, emits in the dark a green light),
and place it in warm sand for twenty-four hours. Take a piece of glass
well cleaned and freed from all grease by means of a lye; put a border
of wax round it, about an inch in height, and cover it all equally over
with the above acid. The longer you let it stand the better, and at the
end of some time the glass will be corroded, and the figures, which
have been traced out with sulphur and varnish, will appear as if raised
above the plane of the glass.” This receipt has been inserted by H.
Krunitz in his Œkonomische Encyclopedie, xi. p. 678.
[224] Klindworth covers the glass with the etching ground of the
engravers; but in the Annals of Chemistry for 1790, ii. p. 141, a
solution of isinglass in water, or a turpentine oil varnish, mixed
with a little white lead, is recommended. Complete instructions for
acquiring this art may be found there also.
[225] De Lapidibus, sect. 19.
[226] See Ephemerid. ac Nat. Cur. 1676, Dec. 1, obs. 13, p. 32; and
Elsholtii De Phosphoris Observationes, Berol. 1681, 4to.
[227] G. C. Kirchmaieri De Phosphoris et Natura Lucis, necnon de Igne,
Commentatio Epistolica. Wittebergæ, 1680, 4to.
[228] Miscellanea Berolin. 1710, vol. i. p. 97. The fluor-spar earth,
or phosphoric earth, as it is called, which in later times has been
found in marble quarries, and which some at present consider as an
earth saturated with phosphoric acid, is mentioned by the Swede Hierne,
in Prodromus Hist. Nat. Sueciæ. Henkel had never seen it.
[229] Watson’s Chemical Essays, ii. p. 277.
[230] Descriptive Catalogue of Tassie’s Engraved Gems, Lond. 1791, 2
vols. 4to, i. p. 51.