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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![•§ IQL] ^issolvins the melt in dilute hydroclilonc acid. The fluoride of potassium ^d titanium is sparingly soluble in water, 1 part requiring 96 parts at 14 . Hydrate of titanic acid whether moist or dried without the aid ot heat dissolves in dilute acids, especially in hydrochloric and sulphuric acids; when a hi^^hly dilute solution of titanic acid m hydrochloric or sulphuric acid but more particularly in the latter, also the one obtained by fusion ■with bisulphate is boiled for a long time, titanic acid is deposited as a white powder (hydrated metatitanic acid) insoluble in dilute acids ; the presence •of much free acid retards the separation and diminishes the quantity of the precipitate. The precipitate which separates from a hydrochloric acid iolution may, indeed, be filtered, but on washing it will pass milky through the filter, unless chloride of ammonium or an acid be added to the washing •water. Solution of potassa throws down titanic acid from its solutions in hydrochloric or sulphuric acid as a bulky white hydrate, which is in- soluble in excess of the precipitant; ammonia, sulphide of ammonium, and carbonate of baryta act in the same way. The precipitate, if thrown ■down cold and washed with cold water, is soluble in hydrochloric acid and in dilute sulphuric acid ; the presence of tartaric acid prevents its formation. Perroeyanide of potassium produces a dark-brown precipitate in acid solutions of titanic acid; infusion of galls gives a brownish precipitate, which speedily turns orange-red. On boiling a solution of titanic acid with hyposulphite of soda, the whole of the titanic acid is thrown down. Phosphate of soda throws down the titanic acid almost completely as phosphate of titanic acid even from solutions containing much hydrochloric acid; the washed precipitate consists of STiOo.POs [Ti,,P„OJ (Merz). Per- oxide of hydrogen colours a solution of titanic acid orange-yellow, but the colour is not taken up by ether when the solution is shaken with it; stannous chloride and zinc dust discharge the colour. The yellow liquid obtained by the action of granulated zinc on aqueous sulphurous acid (hydrosulphurous acid according to Schiitzenberger, hyposulphurous [HoS.OJ according to Bernthsen), produces a red coloration in solutions of titanic acid even when very dilute; on shaking this with ether, the coloured substance is taken up by the ether (E. Fresenius). Zinc or Tin, after a time, produces a pale violet or blue coloration ; subsequently a blue precipitate is formed, which gradually becomes white; the coloration is caused by the reduction of the titanic acid to sesquioxide of titanium. If potassa or ammonia is added to the blue but still clear solution, blue hydrated sesquioxide of titanium separates, which is gradually converted into white hydrated titanic acid with decomposition of the water. The reduction of titanic acid in hydrochloric solution takes place also in the presence of fluoride of potassium (difference from niobic acid), the liquid becoming bright green. The solutions of chloride of titanium in water have different properties according to the way in which they are prepared. If, for example, chloride of titanium is dissolved in water, so that there is no development of heat, a slightly opalescent liquid is obtained, which becomes only slightly turbid on boiling it (titanium chloride solution), whilst the same solution, if kept for some weeks, gives an abundant precipitate when boiled (metatitanium chloride solution). The solutions are further distinguished by the fact that on adding sulphuric or oxalic acid to the former it remains clear, whilst the latter gives a precipitate. If the melt obtained by fusing titanic acid with acid sulphate of potassa is dissolved in cold water, precipitated with ammonia, and the precipitate washed with cold water and dissolved in the smallest possible quantity of hydrochloric acid, it yields a solution of metatitanium chloride; that is, the solution is precipitated by boiling or by adding to it sulphuric or oxalic acid.* * The accounts given by R. Weber (Pogg. Ann., 120, 287) and C. Rammels- berg (Berlin Monatsb., 1874, ^90, Zeit. anal. Chem., 13, 447) of the mode of formation of the solutions of titanium and metatitanium chlorides differ. The matter requires further investigation. I 2](https://iiif.wellcomecollection.org/image/b21966953_0139.jp2/full/800%2C/0/default.jpg)
