Notes on analytical chemistry for students in medicine : extracted from the fifth edition of "Notes for students in chemistry" / by Albert J. Bernays.

  • Bernays, Albert James, 1823-1892.
Date:
1889
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Licence: Public Domain Mark

Credit: Notes on analytical chemistry for students in medicine : extracted from the fifth edition of "Notes for students in chemistry" / by Albert J. Bernays. Source: Wellcome Collection.

Provider: This material has been provided by University of Bristol Library. The original may be consulted at University of Bristol Library.

    45/182 (page 33)
    Strontium chloride, SrCL, is soluble in absolute alcohol, and thus separable, quantitatively, from Barium chloride. 27. Calcium, Ca = 40. Yellow lustrous metal. Dyad. From the fused chloride hy electrolysis. Melts at red heat. Decomposes water: Ca + 2H.,0 = CaH„0„ + H„. Sp. gr. 1-57. Sp. heat 0-167. Calcium oxide, CaO, the only basic Oxide. White, infusible ; lime-light. Quicklime is CaO ; by heating Limestone, CaC03, to redness = CaO + CO,. Slakes with water to Calcium hydroxide, CaH202, a white amorphous powder, requiring 723 parts of cold, and 1330 parts of boiling water for solution. Lime-water is such a solution. Milk of lime is Calcium hydroxide largely mixed with lime-water. Lime-water, alkaline, precipitated by C02 from air, and of course by Na2C03; Silver nitrate is precipitated as Silver hydroxide, AgHO, grey-brown. Chief soluble Salts : CaCl2,6H20 ; CaSO„2H20 ; Ca2N03,4H20. (Chloride of lime, 2CaOCl2, dissolves in water as Calcium chloride, CaCl2, and Calcium hypochlorite, Ca2C10, bleaching litmus, and evolving Cl2 on adding an acid.) Tests for Calcium in soluble salts. V. NH4C1 + (NH4)2C03, white precipitate of CaC03. The Test should be used very sparingly, on account of the solubility of Calcium Bi-carbonate, CaC03,H2C03. [Temporarily hard water contains the Bi-carbonate; it is softened by boiling: into CaCO;i + C02 + H,0. Such water is also softened by adding sufficiency of Calcium Hydroxide: CaC03,H2C03 + CaH202 = 2CaC03 + 2H20.] KOH, white precipitate of Hydroxide CaH202. NH4OH, no reaction. CaS04, of course no reaction. Distinction between Ba, Sr, and Ca: Ba immediately precipitated, Sr on heating, Ca not at all. Concentrated solutions of sulphates precipitate the Chloride, Nitrate, &c, as white Calcium sulphate CaS04,2H20. Ammonium oxalate, (NH4)2C20.„ precipitates white Calcium oxalate, insoluble in acetic acid. This test is decisive if Calcium sulphate has given no precipitate. Soluble salts communicate a yellowish-red color to flame. 28. Magnesium, Mg = 24. Silvery lustrous metal. Dyad. Sp. gr. 1-74. Sp. heat 0 25. Melts at a red heat. By the action of Sodium upon the Chloride by heat: MgCl„ + Na2 = 2NaCl + Mg. Dissolves in the three dilute common acids with evolution of hydrogen; not in KOH. Burns brilliantly to Magnesium oxide, or Magnesia, MgO. Magnesium oxide, MgO, the only base of magnesium. White, amorphous powder; when moistened, blues red litmus, but requires 5142 parts of cold water for solution. Practically insoluble in water, and precipitated by Lime-water from its soluble salts. Chief soluble salts: Sulphate MgSO.„7H20 is Epsom salts; Chloride, MgCl3,GH20 ; Nitrato, Mg2NO„GH20. D