This historic book may have numerous typos and missing text
Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1922 Excerpt: ...made, crush the resulting beads to a fine powder and boil with a few cc. of hydrochloric acid. If this solution, which will usually be clear, is now boiled with a piece of tin, a persistant blue color, due to the reduction of the niobium by the tin. will be obtained. If considerable titanium is present it will also be reduced, but will show a violet color (see titanium, p. 69) before the blue, due to niobium, appears. To distinguish tungstates, which also give a blue color when treated as above, see under tungsten, p. 71. Nitrogen, N--14 The few natural nitrates of the heavy metals are readily decomposed with the evolution of nitrogen dioxide gas, NO2, by heating alone in the closed tube. This gas is easily recognized by its odor and brown color. NOg is given off by nitrates of the lighter elements when they are heated in the closed tube with potassium bisulphate. Oxygen, O--16 1. Oxygen is rarely tested for directly in minerals, but its presence or absence is inferred from the character of the other component elements and their behavior. A few higher oxides, notably those of manganese, give off oxygen when heated in the dosed tube. In making this test the substance is placed in a closed tube in which, a short way above the assay, is also placed a splinter of charcoal. The splinter is heated to redness at the same time, or just before, the substance is ignited. The oxygen, which will be given off if a higher oxide is present, will cause the splinter to burn. To illustrate, the dioxide of manganese, pyrolusite, reacts as follows: 3MnO2 = MnsO4 2O. 2. When some of the higher oxides are dissolved in hydrochloric acid, an amount of chlorine is liberated equivalent to the oxygen which is in excess over that demanded by the lower valence of the metal. The higher ...