Conversations on Mineralogy, Volume 2

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Longmans, Hurst, Rees, Orme, and Brown, 1822 - Mineralogy - 541 pages
 

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Page 226 - ... originates like amber from the consolidation of, perhaps, vegetable matter, which gradually acquires a crystalline form by the influence of time, and the slow action of corpuscular forces.
Page 224 - Jlat or even tints with them ; such as the azure parts of skies, large architectural subjects, and the sea in maps; but the diamond, being turned to a conical point, or otherwise cut to a proper form, is not worn away by the friction of the copper, and, consequently, the lines drawn by it are all of equal thickness. The diamond etching points of Mr. Lowry are turned in a lathe, by holding a thin splinter of diamond against them, as a chisel. DIAMOND DISTRICT, in Brazil. That part of Brazil where...
Page 223 - Glaziers cut glass with them ; glass-cutters' lookingglasses, and other articles of window and plate glass. The glazier's diamond is set in a steel socket, and attached to a wooden handle about the size of a thick pencil. It is very remarkable, that only the point of a natural crystal can be used ; cut or split diamonds scratch, but the glass will not break along the scratch, as it does when a natural crystal is used. An application of the diamond...
Page 222 - Jirst water. — The following are some of the most extraordinary diamonds known : - — one in the possession of the rajah of Mattan, in the island of Borneo, where it was found about a century ago : it is shaped like an egg, and is of the finest water : its weight is 367 carats, or 2 oz. 169 grs. Troy. Another is the celebrated...
Page 222 - Batavia tried to purchase it, and offered in exchange one hundred and fifty thousand dollars, two large brigs of war, with their guns and ammunition, and other cannon, with powder and shot. But the rajah refused to part with a jewel, to which the Malays attach miraculous powers, and which they imagine to be connected with the fate of his family. This...
Page 222 - Borneo, where it was found ulxmt eighty years since. It weighs three hundred" and sixty-seven carats. It is described as having the shape of an egg, with an indentation near the smaller end. Many years ago, the governor of Batavia tried to purchase it, and offered in exchange one hundred and fifty thousand dollars, two large brigs of war, with their guns and ammunition, and other cannon, with powder and shot. But the rajah refused to part with a jewel, to which the Malays attach miraculous...
Page 224 - ... skies, large architectural subjects, and the sea in maps; but the diamond, being turned to a conical point, or otherwise cut to a proper form, is not worn away by the friction of the copper, and, consequently, the lines drawn by it are all of equal thickness. The diamond etching points of Mr. Lowry are turned in a lathe, by holding a thin splinter of diamond against them, as a chisel. DIAMOND DISTRICT, in Brazil. That part of Brazil where the government collects diamonds is not far from Villa...
Page 35 - Yes ; it must be one of the most beautiful places in the world, from the description.
Page 224 - ... the late Wilson Lowry, the eminent engraver, and first inventor of the mechanical methods now used in that part of the process called etching. He applied them to the purpose of drawing or ruling lines, which are afterwards to be deepened by aqua-fortis. Formerly steel points, called etching-needles, were used for that purpose, but they soon became blunt by the friction against the copper.

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