A History of Inventions, Discoveries, and Origins (Vol. 1&2). Johann Beckmann

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СКАЧАТЬ href="#ulink_935232c6-d866-5116-87f7-d2da55b6242f">330 See Peter le Vieil’s Kunst auf Glas zu malen, Nuremberg, 1779, 4to, ii. p. 25. This singular performance must, in regard to history, particularly that of the ancients, be read with precaution. Seldom has the author perused the works which he quotes; sometimes one cannot find in them what he assures us he found, and very often he misrepresents their words.

331 In what the art of Abraham Helmback, a Nuremberg artist, consisted, I do not know. Doppelmayer, in his Account of the Mathematicians and Artists of Nuremberg, printed in 1730, says that he fortunately revived, in 1717, according to experiments made in a glass-house, the old red glass; the proper method of preparing which had been long lost.

332 Ferber’s Briefe aus Welschland. Prague, 1773, 8vo, p. 114.

333 The devastations to which the productions of this beautiful art have been subjected are deeply to be regretted. It appears from the interesting Account of Durham Cathedral, published by the Rev. James Raine, that there was much fine stained glass in the fifteen windows of the Nine Altars which

      “shed their many-colour’d light

       Through the rich robes of eremites and saints;”

      until the year 1795, when “their richly painted glass and mullions were swept away, and the present plain windows inserted in their place. The glass lay for a long time afterwards in baskets on the floor; and when the greater part of it had been purloined the remainder was locked up in the Galilee.” And in 1802 a beautiful ancient structure, the Great Vestry, “was, for no apparent reason, demolished, and the richly painted glass which decorated its windows was either destroyed by the workmen or afterwards purloined.” The exquisite Galilee itself had been condemned, but was saved by a happy chance.

334 In 1774 the French Academy published Le Vieil’s treatise on Glass-painting. He possessed no colour approaching to red, except the brick-red or rather rust-coloured enamel subsequently mentioned in the text, derived from iron.

335 It appears by a boast of Suger, abbot of St. Denis, which has been preserved, that the ancient glass-painters pretended to employ sapphires among their materials; hence, perhaps, the origin of the term Zaffres, under which the oxide of cobalt is still known in commerce.

336 Oxide of chromium is now substituted for the copper.

337 That such was the method in use, an attentive examination of old specimens affords sufficient evidence. One piece that I possess exhibits large bubbles in the midst of the red stratum; another consists of a stratum of red inclosed between two colourless strata: both circumstances plainly point out the only means by which such an arrangement could be produced.

338 In 1793, the French government actually collected a quantity of old red glass, with the view of extracting the gold by which it was supposed to be coloured! Le Vieil was himself a glass-painter employed in the repair of ancient windows, and the descendant of glass-painters, yet so little was he aware of the true nature of the glass, that he even fancied he could detect the marks of the brush with which he imagined the red stratum had been laid on!

339 [M. Langlois names the following writers: “Neri en 1612, Handicquer de Blancourt en 1667, Kunkel en 1679, Le Vieil en 1774, et plusieurs autres écrivains à diverses époques, decrivaient ces procédés.” (p. 192.) He fixes the restoration of the art in France at about the year 1800, when Brongniart, who had the direction of the Sèvres porcelain manufacture, worked with Méraud at the preparation of vitrifiable colours, p. 194. Among modern artists he particularly mentions Dihl, Schilt, Mortelègue, Robert, Leclair, Collins, and Willement.]

340 Bulletin de la Société d’Encouragement pour l’Industrie Nationale, 1826.

341 Though it is difficult to produce the copper-glass uniformly coloured, it is easy to obtain streaks and patches of a fine transparent red. For this purpose it is sufficient to fuse together 100 parts of crown-glass with one of oxide of copper, putting a lump of tin into the bottom of the crucible. Metallic iron employed in the same way as the tin throws out a bright scarlet, but perfectly opake.

342 “Dr. Lewis states that he once produced a potfull of glass of beautiful colour, yet was never able to succeed a second time, though he took infinite pains, and tried a multitude of experiments with that view.” Commerce of Arts, p. 177.

343 [At the recent meeting of the British Association for the Advancement of Science, held at Cambridge (June 1845), M. Splittgerber exhibited specimens of glass into the composition of which gold entered as a chloride. These specimens were white, but upon gently heating them in the flame of a spirit-lamp, they became a deep-red. If again the same reddened glass is exposed to the heat of an oxygen blowpipe, it loses nearly all its colours, a slight pinkiness only remaining.]

      SEALING-WAX.

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Writers on diplomatics mention, besides metals, five other substances on which impressions were made, or with which letters and public acts were sealed, viz. terra sigillaris, cement, paste, common wax, and sealing-wax344. The terra sigillaris was used by the Egyptians, and appears to have been the first substance employed for sealing345. The Egyptian priests bound to the horns of the cattle fit for sacrifice a piece of paper; stuck upon it some sealing-earth, on which they made an impression with their seal; and such cattle only could be offered up as victims346.

Lucian speaks of a fortune-teller who ordered those who came to consult him to write down on a bit of paper the questions they wished to ask, to fold it up, and to seal it with clay, or any other substance of the like kind347. Such earth seems to have been employed in sealing by the Byzantine emperors: for we are told that at the second council of Nice, a certain person defended the worship of images by saying, no one believed that those who received written orders from the emperor and venerated the seal, worshiped on that account the sealing-earth, the paper, or the lead348.

Cicero relates that Verres having seen in the hands of one of his servants a letter written to him from Agrigentum, and having observed on it an impression in sealing-earth (cretula), he was so pleased with it that he caused the seal-ring with which it was made to be taken from the possessor349. The same orator, in his defence of Flaccus, produced an attestation sent from Asia, and proved its authenticity by its being sealed with Asiatic sealing-earth; with which, said he to the auditors, as you daily see, СКАЧАТЬ