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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![soluble salts do not affect vegetable colours; they are decomposed when ignited in a glass tube, with the exception of the chloride, bromide, and iodide of barium. The insoluble salts dissolve in dilute hydrochloric acid, except sulphate of baryta and silicofluoiide of bai^ium. Niti-ate of baryta and chloride of barium are insoluble in alcohol, and do not deliquesce in the air. Concentrated solutions of baryta are precipitated by concentrated hydrochloric or nitric acid if the acid is added in large proportion, chloride of barium and nitrate of baryta being insoluble in the concentrated aqueous solutions of the said acids. 3. Ammonia produces no precipitate in aqueous solutions of salts of baryta; potassa or soda (free from carbonic acid) only in higlily concentrated solutions. Water redissolves the bulky precipitate of crystals of hydrate of baryta, BaO,HO + 8aq [BaH„0,,,8H,,0], pro- duced by potassa or soda. 4. Carbonates of the alkalies throw down carbonate of barytii, BaO,CO„ [BaCOs], in the form of a white precipitate. If the solution was pi'eviously acid, complete precipitation takes place only after ]ie;it- ing the liquid. The precipitate is soluble in chloride of ammonium to a trifling yet clearly perceptible extent; carbonate of ammonia there- fore produces no precipitate in very dilute solutions of baryta containing much chloride of ammonium. 5. Sulphtiric acid and all the soluble sulphates, more paiticularly also solution of sulphate of lime, produce, even in very dilute solutions, a heavy, finely pulverulent, white precipitate of sulphate of baryta, BaOjSOj [BaSOj], which is insoluble in alkalies, nearly so in dilute acids, but perceptibly soluble in boiling concentrated hydrochloric and nitric acids, as well as in concentrated solutions of ammonia salts; in the latter, however, only if there is no excess of sulphuric acid or a sulphate present. This precipitate is generally formed immediately the reagent is added ; from highly dilute solutions, however, especially when strongly acid, it separates only after some time. 6. Hydrofluosilicic acid throws down silicofluoride of barium, BaF,SiF2 [BaSiFJ, in the form of a colotirless crystalline quickly subsiding precipitate. In dilute solutions, this precipitate is formed only after the lapse of some time : it is perceptibly soluble in hydrochloric and nitric acids. The addition of an equal volume of alcohol hastens the precipitation, and makes it so complete that the filtrate remains clear on the addition of sulphuric acid. 7. Phosphate of soda in neutral or alkaline solutions of baiyta salts prod\ices a white precipitate of phosphate of baryta, 2BaO,B[0,PO. [BaHPOJ, which is soluble in free acids. Addition of ammonia only slightly increases the quantity of this precipitate, ii portion of which is converted into basic phosphate of baryta, oBaOjPOj [BajlPOJ.J, by this reagent. Chloride of ammonium dis- solves the precipitate to a clearly perceptible extent. 8. Oxalate of ammonia in moderately dilute solutions produces m Avhite pulverulent precipitate of oxalate of baryta, 2BaO,Cp„ + 2aq [BaCA,H,0], which is soluble in hydrochloric and nitric acids. When recently thrown down, this precipitate dissolves also in oxalic and acetic acids; but the solutions speedily deposit acid oxalate of baryta, BaO,HO,Cp, + 2aq [BaH,C,0„.2H,0], in the form of a cryst.illine powder.](https://iiif.wellcomecollection.org/image/b21966953_0118.jp2/full/800%2C/0/default.jpg)
