Volltext Seite (XML)
TESTING. 99 salt of phosphorus in the outer flame, yield a clear yellow glass, and in the inner flame, a beautiful green glass. The reaction with borax is the same as that of iron. Molybdenum, Tungsten, Tantalum, Pelopiwm, Niobium, Titanium. Molybdenum, in the inner flame, with salt of phosphorus, produces a green glass, hut with borax, a brown glass. Tungsten occurs only as tungstic acid, which, in some cases, may be known by its forming, with salt of phosphorus in the outer flame, a colourless, or yellow glass, and in the inner flame a beautiful blue glass, which, as long as it is warm, appears green. When iron is present, however, the glass is blood-red. More generally, tungstic acid may be discovered by melting the assay with five times its weight of soda in a platinum capsule, dissolving in water, filtering, and. adding hydrochloric acid, which throws down the tungstic acid. The precipitate is white when cold, and citron yellow when heated. Tantalum, as tantalic acid, is not readily distinguishable before the blow-pipe: in salt of phosphorus it is soluble readily, and in largo quantities, forming a clear glass, which does not become opaque on cooling, and is not turned blue by solution of cobalt. Tins process serves to distinguish tantalic acid from glucine, yttrin, zirconia, and alumina. Its actual recognition may be best effected in the following mannerThe assay is melted with twice its weight of nitre and three times its weight of soda, in a platinum capsule, dissolved in water, filtered, and hydrochloric acid added; the tantalic acid is precipitated as a white powder which does not become yellow when heated. 1‘elopic acid forms a colourless glass with borax. With salt of phosphorus it yields a clear colourless glass in the outer flame, and in the inner flame, on charcoal, a clear brown glass inclining sometimes to violet. The glass becomes blood-red on the addition of iron. Niobic acid with borax in the outer flame forms a colourless glass; in the inner flame a violet glass. With salt of phos phorus it forms a transparent colourless glass in the outer flame, and a violet or blue glass, when the proportion of the acid is not too small, in the inner flame. The glass becomes blood-red on the addition of iron. Titanium.—In anataso, rutile, brookito, and sphene, the pre sence of titanic acid is shown by the fonnation of glass with salt of phosphorus, which is, and remains, colourless in the outer flame, but in the inner flame is yellow, when hot, and, while cooling, becomes first red and then violet. When iron F 2
