 | Charles William King - 1860 - 582 Seiten
...black and white layers. These colours are produced artificially by boiling the stone, a kind of flint, for several days in honey and water, and then soaking...in sulphuric acid to bring out the black and white, and in nitric to give the red and white layers. They all come from Germany, where the secret was cither... | |
 | Henry William Bristow - 1861 - 478 Seiten
...for their rarity only, but for their beauty as works cf art. See ONICOLO, also SARD. The tints of the Onyx may be heightened by boiling it for several days in honey ard water, and then soaking it in sulphuric acid to bring out the black and white layers; or in nitric... | |
 | Hodder Michael Westropp - 1867 - 508 Seiten
...imported from Germany, but their coloxirs are produced artificially by boiling the stone, a kind of flint, for several days in honey and water, and then soaking...in sulphuric acid to bring out the black and white, arid in nitric to give the red and white layers. They are, however, considered of little value. •... | |
 | David Page - 1874 - 402 Seiten
...white, are the most frequent alternations of colour ; but these can be intensified by boiling the stone for several days in honey and water, and then soaking it in sulphuric acid. Opals. . "TheOflals, or Opaline varieties, are, as already stated, hydrous silicas, consisting of from... | |
 | Hodder Michael Westropp - 1878 - 640 Seiten
...imported from Germany, but their colours are produced artificially by boiling the Btone, a kind of flint, for several days in honey and water, and then soaking...in sulphuric acid to bring out the black and white, and in nitric to give the red and white layers. They are, however, considered of little value. ACHATES... | |
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... valuable stones are from India. Some of the pieces of sardonyx used by the ancient engravers for their most important works were of enormous dimensions. At the present day onyxes and sardonyxes are imported from Germany, but their colours are produced,... 