Licence: Public Domain Mark
Credit: Qualitative chemical analysis / by C. Remigius Fresenius. Source: Wellcome Collection.
Provider: This material has been provided by the Royal College of Physicians of Edinburgh. The original may be consulted at the Royal College of Physicians of Edinburgh.
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![9 Chromate of potassa, ami dichvoinate of potassa, produce a bright yellow precipitate of chromate of baryta, BaO,Cr03 [BaCrO,], even in very dilute solutions of salts of baryta. Ihe precipitate dis- solves readily in hydrochloric or nitric acid to a yellowish red solution, from which it is thrown down again by ammonia; it is insoluble m acetic acid and chromic acid. i ^ , -^i, n 4. 10 If soluble salts of baryta in powder are heated with dilute spirit of wine, they impart to the flame a greenish-yellow colour. 11 If salts of baryta are held on the loop of a platinum wire in the fusing zone of the Bunsen gas flame, the part of the flame above the sample is coloured yellowish green; or if the baryta salts are held in the inner spirit blowpipe flame, the same coloration is im- parted to the part of the flame before the sample. With soluble baryta salts, and also Avith carbonate and sulphate of baryta, the reaction takes place immediately or very quickly; but the phosphate must be pre- viously moistened with sulphuric acid or hydrochloric acid; by similar treatment, baryta may be detected by the flame coloration also in siUcates decomposable by acids. Silicates which are not decomposed by hydrochloric acid must be fused with carbonate of soda, when the car- bonate of baryta produced will show the reaction. It is characteristic of the yeUowish-green baryta coloration of the flame that it appears bluish-green when viewed through the green glass. If the sulphates are used for the experiment, the presence of Hme and strontia will not interfere with the reaction. The baryta spectrum is shown in the coloured plate. The green Hues, a and /3 are the most intense; y is less marked, but still characteristic. Platinum wire sometimes contains barium (Kraut), so that it is well to see first whether it wiU give a barium spectrum by itself. 12. Cold solutions of bicarbonates of the alkalies or of carbonate of ammonia do not decompose sulphate of baryta, or more accurately, they decompose that salt only to an almost imperceptible extent; the .same applies to a boiling solution of 1 part of carbonate and 3 parts of sulphate of potassa. The repeated action of boiling solutions of monocarbonates of the alkalies on sulphate of baryta, however, at last completely decomposes that salt, and it is also readily decomposed by fusion with carbonates of the alkalies; a sulphate of the alkali, solvible dn water is formed, together with carbonate of baryta, insoluble in that menstruum. §9G. 5. Strontia, SrO [SrO]. 1. Strontia, its hydrate and its salts have nearly the same general properties and reactions as baryta and its corresponding com- pounds. Hydrate of strontia is more sparingly soluble in water than hydrate of baryta. Chloride of strontium dissolves in absolute alcohol and deliquesces in moist air. Nitrate of strontia is insoluble in absolute alcohol and does not deliquesce in the air. 2. With ammonia, potassa, and soda, and also with the car- Taonates of the alkalies and with phosphate of soda, the salts of strontia give nearly the same I'eactions as the salts of baryta. Car- lionate of strontia, however, is somewhat less soluble in chloride of am- monium than carbonate of iDaryta.](https://iiif.wellcomecollection.org/image/b21966953_0119.jp2/full/800%2C/0/default.jpg)
