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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.

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    Ammonia precipitates them only partially as hydrate, a soluble double salt being formed at the same time. Soluble magnesia-salts are not precipitated in the cold by bicarbonate of ammonia, and only partially and slowly by carbonate and sesqui-carbonate of ammonia; the precipitate obtained by the latter reagents, appears quicker and more completely on ebullition. All these precipitates are redissolved on the addition of a sufii- cient quantity of chloride of ammonium. But, as already mentioned, the precipitate, which in the presence of ammonia is produced by phosphate of soda, (this precipitate is a tribasic phosphate, 2 MgO, NH ,O, PO, +12 aq), remains insoluble even in a very great excess of chloride of ammonium. When magnesia-salts are heated upon charcoal before the blowpipe, moistened with a drop of solution of mtrate of cobalt, CoO, NO, and ignited again powerfully, for a short time, the salt assumes a pale red colour. But this is not always perceptible, when other oxides are present. , Magnesia may, therefore, be separated from baryta, strontia, and lime, simply by carbonate of ammonia, in the presence of chloride of ammonium and ammonia. Magnesia: remains in solution, while the three other earths are completely precipitated (especially on a slight increase of temperature and addition of some ammonia.) ‘The filtrate may then be tested for magnesia with phosphate of soda. In order to detect the fixed alkalies when in conjunction with magnesia, it is necessary to get rid of the magnesia and all the ammoniacal salts. This is effected by evaporating the solution and igniting. The residue is then heated with water, a solution of baryta (or, what is equally good, sulphide of barium, Ba 8), added to the liquid as long as a precipitate is formed. The excess of baryta, after filtration, is then separated either by sulphuric acid, or carbonate of ammonia, and. the residue obtained by evaporating the filtrate, ignited. This residue must now be tested for potassa, soda [and lithia], as above explained. When, however, the solution to be
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