A Manual of Blowpipe-analysis, and Determinative Mineralogy

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T. E. Zell, 1861 - Blowpipe - 176 pages
 

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Page 13 - A mouth-piece, a, of box-wood, horn or ivory is convenient, though not necessary. (Fig. 1.) 2. Any kind of flame may be used for the blow-pipe, provided it be not too small. Some of the older chemists used common candles in preference, and it must be confessed that, in the majority of cases, the heat produced by the flame of a good sperm candle is quite sufficient. Berzelius recommended an oil lamp with a flat wick, which is now in general use as " Berzelius's Blow-pipe Lamp...
Page 28 - The experiment with borax is generally made on platinum wire, where the color of the bead is more readily observed ; Ch. is used only in such cases where the substance under examination contains metallic oxides which are easily reduced. It is not sufficient to observe the color of the bead after cooling ; but all changes of color which take place during the action of the flame, and through all the various stages of cooling, should be carefully noticed. Some substances possess the property of forming...
Page 48 - ... bead is then taken from the charcoal, enveloped in a piece of paper, and struck lightly with a hammer, by which means the phosphuret of iron is separated from the surrounding flux. It exists as a metallic-looking button, attractable by the magnet, frangible on the anvil, the fracture having the colour of iron. If the substance under assay contained no phosphoric acid, the iron wire will keep its form and metallic lustre, excepting at the ends, where it will be oxidated and burnt. The substance...
Page 35 - ... open glass tube, evolve sulphurous acid and yield a sublimate of arsenous oxide. To show in a very decisive manner the presence of arsenic in any of its combinations with sulphur, the powdered assay [No. 80] is mixed with four volumes of neutral oxalate of potassa and a little charcoal powder, or with six parts of a mixture of equal parts of cyanide of potassium and carbonate of soda, the mass introduced into a tube sealed at one end, and heat applied, at first very gently but gradually raised...
Page 56 - Breithaupt, is as follows: 1. Talc; common laminated light-green variety. 2. Gypsum ; crystalline variety. 3. Calcite; transparent variety. 4. Fluorite; crystalline variety. 5. Apatite; transparent variety. 6. Orthoclase; white cleavable variety. 7. Quartz; transparent. 8. Topaz; transparent. 9. Corundum; cleavable varieties. 10. Diamond.
Page 55 - Chapman: 1. Yields easily to the nail. 2. Yields with difficulty to the nail, or merely receives an impression from it. Does not scratch a copper coin. 3. Scratches a copper coin; but is also scratched by it, being of about the same degree of hardness. 4. Not scratched by a copper coin; does not scratch glass. 5. Scratches glass, though rather with difficulty, leaving its powder on it.
Page 125 - Scolecite, on being heated, curls up like a worm, and finally melts to a bulky, shining slag, which in the inner flame becomes a vesicular, slightly translucent bead; hardness, 5.5.
Page 56 - Scratches glass, though rather with difficulty, leaving its powder on it. Yields readily to the knife. 6. Scratches glass easily. Yields with difficulty to the knife. 7. Does not yield to the knife. Yields to the edge of a file, though with difficulty. 8. 9. 10. Harder than flint.
Page 56 - ... scratch a smooth surface of the successive members of the scale with a sharp corner of the substance to be examined ; thus, if it scratches fluor-spar and is scratched by apatite, the hardness is between 4 and 5. Or again, the relative hardness of a mineral may be determined by abrading one of its edges with a file. If the file abrades the mineral under trial with the same ease as fluor-spar, and produces an equal depth of abrasion with the same force, the hardness is said to be 4. If the mineral...
Page 51 - ... oxidized, and the button assumes a rotary motion; at this period the blast is discontinued, the assay is allowed to cool, and when perfectly cold the lead button is separated from the glass by some slight strokes with a hammer. It is now placed on a cupel of bone-ash and treated with the O Fl until it again assumes a rotatory motion. If much copper or nickel is present, the globule becomes covered with a thick infusible crust, which prevents the aimed-at oxidation; in this case another small...

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