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Outlines of the course of qualitative analysis followed in the Giessen laboratory / By Henry Will ; With a preface by Baron Liebig.

  • Heinrich Will
Date:
1846
Catalogue details

Licence: Public Domain Mark

Credit: Outlines of the course of qualitative analysis followed in the Giessen laboratory / By Henry Will ; With a preface by Baron Liebig. Source: Wellcome Collection.

    69/152 page 53
    SELENIC ACID, SULPHUROUS ACID. TD) The white precipitate which forms on addition of these acids to a soluble baryta salt, is however easily dissolved by water. The compounds of sulphuric acid with the fixed alkalies, with the alkaline earths and oxide of lead, are not decomposed on being ignited alone; all the other sulphates are destroyed by ignition, sulphuric acid and sulphurous acid or oxygen, accord- ing to the nature of the base, being disengaged. All the sulphates are decomposed on being ignited with charcoal ; if in this decomposition an alkali (carbonate of soda, cyanide of potassium) be present, an alkaline sulphide is pro- duced which disengages hydrosulphuric acid, when treated with an acid, and blackens a bright silver surface on bemg moistened with water. The same behaviour is exhibited by the compounds of sulphurous acid, and in general all the acids of sulphur (detection of sulphates before the blowpipe). The sulphates soluble in water and acids, are completely decomposed by fusion with an alkaline carbonate, but only partially on boiling with a solution of the alkali in water ; in the filtered liquid saturated with hydrochloric acid a preci- pitate of sulphate of baryta is produced on addition of a soluble baryta salt. [SELENIC ACID.] HO, SeO,. Selenic acid and seleniates very much resemble sulphuric acid and sulphates, m their chemical deportment ; seleniates however are decomposed on boiling with hydrochloric acid, selenious acid bemg formed with disengagement of chlorine ; the decomposed seleniate now possesses the property of deco- lorising sulphindigotic acid ; it 1s precipitated by sulphurous acid, or hydrosulphuric acid (v. p. 52), but no longer by chloride of barium. On being exposed to the inner flame of the blow- pipe with phosphorus salt or carbonate of soda, all compounds of selenium disengage a characteristic horseradish-lke odour. SULPHUROUS ACID. Soe. Sulphurous acid is formed on burning sulphur in contact with the air; at the common temperature it 1s a transparent
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