This is rendered in the Latin edition ‘_inque illarum exaltatione ad magnum ascendit gradum_.’ It should, perhaps, be translated ‘to a high pitch of excellence.’ Footnote 214: There is an exquisitely engraved covered beaker of this period at South Kensington bearing the arms of the Elector of Trèves (Plate XLII.). Footnote 215: Especially by Doppelmayr in his _Historische Nachricht von der Nürnbergischen Mathematicis und Künstlern_, Nürnberg, 1730. A pretentious work, written in the Frenchified German of the day, and very inferior as an authority to Sandrart. Footnote 216: It was here that was first developed that hybrid type of drinking-glass which passed over to England early in the eighteenth century. In these glasses the engraved bowl carries us back to Germany, and the air or opaque twisted stem to the _vetro di trina_ of Venice. Footnote 217: Quite early in the eighteenth century we find an account of a process by which a gas possessing the property of attacking glass may be made by steeping the ‘hesphorus’ or ‘Bohemian emerald’ in spirits of nitre. As we are told that this ‘hesphorus’ when heated emits a green light, we may safely identify it with fluor-spar (fluoride of calcium). Footnote 218: A circular plaque of this character, with a pious inscription, in the Germanic Museum at Nuremberg, has been ascribed to Henry Schwanhart. It is dated 1686 (reproduced by Gerspach, p. 266). Footnote 219: We must remember that at this time little distinction was drawn between the researches of the chemist and the alchemist. Footnote 220: The ruby glass of our old Gothic churches was, however, without exception obtained from copper. But the belief that it contained gold led in France to the destruction of much of this glass at the time of the Revolution. Footnote 221: This book may be best consulted in the French translation, said to be by the Baron D’Holbach (Paris, 1752). Here we have in its final form the little book of Neri, which has passed through the translator’s crucible as many as four times—from Italian to English, then to Latin, to German, and finally to French. For there was, too, an Amsterdam edition in Latin (1668) which came between the English and Kunckel’s version. But, unlike the gold of the alchemist, the work really increased in value during these transformations. Several curious treatises, in the manner of the time, half alchemistic, half scientific, are to be found at the end of the French translation, including a rendering into French of Orschall’s _Sol sine Veste_. Footnote 222: The somewhat obscure relations of these two men, Kunckel and Orschall, with Cassius, the reputed discoverer of the purple that goes by his name (as well as with the son of the latter), is explained by Beckmann (_History of Inventions_, vol. i. p. 126). Footnote 223: