A treatise on chemistry. Vol. 1, The non-metallic elements / by Sir H.E. Roscoe & C. Schorlemmer ...

  • Henry Enfield Roscoe
Date:
1881
Catalogue details

Licence: Public Domain Mark

Credit: A treatise on chemistry. Vol. 1, The non-metallic elements / by Sir H.E. Roscoe & C. Schorlemmer ... Source: Wellcome Collection.

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

    117/792 (page 101)
    then burns with a flame coloured violet by the presence of the vapours of the metal. Sodium, likewise, decomposes water, but the hydrogen in this case does not take fire spontaneously unless the water be hot, or the motion of the bead of metal be stopped, as when the metal is thrown on to a viscid starch- paste or on to a moistened sheet of blotting-paper, in which cases the globule of melted metal remaining in one place be- comes hot enough to cause the ignition of the hydrogen, which then burns with the yellow flame characteristic of the sodium compounds. If the blotting-paper be previously stretched upon a wooden tray and moistened with a red solution of litmus, the track of the molten potassium or sodium, as it runs over the paper, will be seen by a blue line showing the formation of an alkaline product. In order to collect the hydrogen thus evolved, the small clean gloljule of sodium may be caught and depressed below the surface of the water by means of a little sieve of wire- gauze under the open end of a cylinder; the bubbles of gas then rise and may be collected, as shown in Fig. 14. Fig. ]4. (?,) By passing steam over red-hot iron wire or iron borings placed in an iron tube and heated in a furnace as shown in Fig. 15, (a) being a retort in Avhich water is boiled. The iron is converted into the black or Ferrosoferric oxide FegO^ and hydrogen is evolved, thus: 3Fe^-4H5P = Fe30,^-4II^. ' Explosions may ensue if the sodium adheres to the glass.