A handbook of chemical analysis : (adapted to the unitary notation) / based on the fourth edition of H. Will's Anleitung zur chemischen Analyse by F.T. Conington.

  • Will, Heinrich, 1812-1890.
Date:
1858
Catalogue details

Licence: Public Domain Mark

Credit: A handbook of chemical analysis : (adapted to the unitary notation) / based on the fourth edition of H. Will's Anleitung zur chemischen Analyse by F.T. Conington. Source: Wellcome Collection.

    42/348 (page 18)
    c. SulpJluinc Acid, SO'il-.—An oily colourless heavy liqind, powerfully corrosive, boiling at 327°. It is soluble in water in all proportions: the combination is attended with great heat. It is so hygroscopic (i. e. has so strong a tendency to take up water) that it is employed to dry substances Avhich will not bear an elevation of temperature. It is the most powerful acid with Avhich we are acquainted, and in the wet way will displace all other acids from their salts. It is bibasic; and therefore forms acid as well as normal salts (p. 6). All normal and acid sulphates (with the few following excep- tions) are soluble in water: basic sulphates are insoluble in water, soluble in dilute acids. Sulphate of barium is entirely insoluble in water or dilute acids: sulphate of calcium is difficultly soluble in water (in 500 parts); sulphate of strontium still less soluble (in 9000 parts); and sulphate of lead still less (in 22,000 parts), (c) The best reagent for the detection and estimation of sul- phuric acid in solutions is chloride, or nitrate of barium, either of which gives a white, finely divided pi'ccipitate of sulphate of barium (SO^^Ba^), which is very slightly soluble in concentrated nitric or hydrochloric acids. The solution of the sulphate should first be acidulated with hydrochloric acid. Care must be taken not to have too much free nitric or hydrochloric acid present; for, as chloride and nitrate of barium are much less soluble in strong acids than they are in water, their addition to a strongly acid solution might cause a precipitate, even if no sulphuric acid were present. When, therefore, eitlier of these reagents causes a pi-ecipitate, excess of water should be added, which will at once dissolve any chloride or nitrate of barium that may be precipitated, but will not dissolve the sulphate. If the amount of sulphate present be very minute, the solution (especially if it contains nitric acid) should be allowed to stand some time after the addition of the barium-salt. If sulphate of barium be preci- pitated from a solution containing a nitrate, it generally cai'ries doAvn with it some nitrate of barium, which cannot be entirely removed by washing with water. In such cases, therefore, in quantitative analysis, the precipitate must be ignited (in order to decompose the nitrate), moistened with hydrochloric acid, and