This historic book may have numerous typos and missing text. Purchasers can usually download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1913 edition. Excerpt: ... of Paris plates by adding a mixture of 40 per cent, iodine and 60 per cent, sulphur.1 The addition of von Kobell's mixture of potassium iodide and sulphur in equal parts to the substance treated serves to distinguish the lead sublimate from that of bismuth, lead iodide beingmore intensely yellow than ...
Read More
This historic book may have numerous typos and missing text. Purchasers can usually download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1913 edition. Excerpt: ... of Paris plates by adding a mixture of 40 per cent, iodine and 60 per cent, sulphur.1 The addition of von Kobell's mixture of potassium iodide and sulphur in equal parts to the substance treated serves to distinguish the lead sublimate from that of bismuth, lead iodide beingmore intensely yellow than the oxide, while bismuth iodide is a brilliant red. If the sublimate or the substance is white after the oxidising flame has been employed, allow it to cool, add cobalt nitrate in solution, and reheat as strongly as possible in the oxidising flame. When cool, look for any colour imparted to the sublimate or the residue. A splinter of the mineral may often be conveniently treated with cobalt nitrate. 8. Treat the powdered mineral, with or without the addition of sodium carbonate, on charcoal in the reducing flame. Press out the residue on an anvil or in an agate mortar if metallic beads are not readily apparent. Even if no bead arises, test the powdered residue to see if it has become magnetic, iron, cobalt, or nickel being thus indicated. In such cases, test the material taken up by the bar magnet by treating it in beads of borax and microcosmic salt. In all cases where metallic beads are found, rub the surface of the bead, which usually becomes oxidised as it cools, and flatten out the bead on an anvil to observe its properties. Tin, lead, and silver are easily distinguished by treatment of the bead on charcoal in the oxidising flame. Tin oxidises throughout to a white powder; lead becomes crusted over with orange oxide; both these beads give a streak of oxide beyond them on the charcoal. Silver may darken on cooling, but otherwise remains unchanged. 9. Sulphur is often present, as in sulphates, without giving 1 Wheeler and Luedeking, ..
Read Less
