A course of qualitative chemical analysis / by Wm. Geo. Valentin.

  • Valentin, William George.
Date:
1876
Catalogue details

Licence: Public Domain Mark

Credit: A course of qualitative chemical analysis / by Wm. Geo. Valentin. Source: Wellcome Collection.

    22/298 (page 10)
    nitre, or Gliilisaltpetre, NOdSTao; as sulphate or glauber salt, S02]Srao2, 10OH2; as biborate, B4O6Nao2,10OH2; as glauberite, SjOiNaOijCao, and as cryolite, 6NaF,Al2F6, and in many silicates, of which albite may be taken as the representative. All natural sodium compounds, with the exception of the last two minerals, are soluble in water. REACTIONS IN THE DRV WAY. We almost exclusively rely for tbe detection of sodium upon tbe characteristic colour—an intense golden-yellow—which its com- pounds impart to the outer flame of the blowpipe. Its spectrum consists of one bright double line, coinciding with the D line of the solar spectrum. Some sodic salts are readily recognised by their characteristic taste, especially rock salt and cubic nitre. REACTIONS IN THE WET WAT. We employ a solution of sodic chloride, NaCl. Sodic salts are even more freely soluble than potassic salts, and platinic chloride or tartaric acid give no precipitates. Hydro- fluosilicic acid gives a gelatinous precipitate from concentrated (aqueous) solutions only; the precipitate is, however, insoluble in alcohol. Sb02Ko (potassic iiictantinioimtc) produces a white crystalline pre- cipitate of sodic nictantimonatc from neutral or slightly alkaline solutions, if they aro not too dilute. The precipitate is insoluble in alcohol. (The solution to be tested should only contain alkali metals.) Sodic hydrate and sodic carbonate act in every respect like potassic hydrate and carbonate. Pure sodic hydrate is now prepared from the metal sodium, and deserves the preference over potassic hydrate.* 3. AMMONIUM.—Am = NH4. Atomic weight, 18.— REACTIONS IN THE DRY WAY. Ammonic salts, when heated in a test-tube, volatilize, either entirely or partially. Salts with fixed acids, such as phosphoric acid, lose ammonia, NHS. Salts of ammonium with volatile acids can be volatilised, either with decomposition, such as the nitrate, nitrite, sulphate, the latter with formation of mixed vapour of nitrogen, water, ammonia, and sulphurous anhydride; or without decomposition, such as the cyanide ; or partial dissociation only, such as the chloride, bromide, iodide: the latter salts condense again, for the most part unchanged; they sublime, and are found in the upper part of the test-tube. * The student who has not the advantage of attending a course of lectures on chemistry should make himself familiar, by reading a good Manual of Chemistry, with the properties of the various salts of potassium and sodium, also with (lie i nteresting processes of manufacturing sodic carbonate from the chloride; sodic silicate (water-glass) ; potassic chlorate, &c., &c.