Volume 1

The chemical pocket book, or Memoranda chemica, arranged in a compendium of chemistry / By James Parkinson, Hoxton.

  • Parkinson, James, 1755-1824.
Date:
1809
Catalogue details

Licence: Public Domain Mark

Credit: The chemical pocket book, or Memoranda chemica, arranged in a compendium of chemistry / By James Parkinson, Hoxton. Source: Wellcome Collection.

    37/424 (page 13)
    Lime also has a strong affinity for alumine and silica. Alumine unites with the lime of lime-water, and forms an in- soluble compound; and being mixed with lime, the solution of both with the fixed alkali is facilitated. Lime-water being mixed with a solution of silica in pot-ash, a precipitate com- posed of the two earths is deposited, w hich is insoluble in w ater, but dissolves in the acids, even in distilled vinegar. It is most frequently found native with acid excepting in tremclite;which is a combination of silica and carbonate of lime : the earthy compounds containing lime generally consist of lime, alumine, and silica. Magnesia has a strong affinity for alumine, but manifests none for the other earths. Unlike lime, it impedes the solution of alumina in pot-ash. It forms a fusible compound with silica ; but its mixture with barytes, strontia, lime or alumine is not fusible in the heat of our furnaces. Alumine has an affinity for the alkaline earths, magnesia, and silica. When solutions of alumine and of silica in pot- ash are mixed together, the mixture becomes opaque and gelatinous, and the percipitate contains both alumine and silica ; insoluble in water, but soluble in acids, even in vinegar. Alu- mine facilitates the solution of silica in pot-ash. It will only enter into fusion with lime, except in the case of triple earthy mixtures. • 4 Silica, as already observed, has an affinity for the alkaline earths, and alumina. It has also an affinity for zirconia. Alu- mina is the only earth with which it does not fuse. Some of the strong earthy combinations fuse, at a certain degree of heat.; but under the same,or even a higher degree,be- come again solid, and undergo a second fusion at a much higher temperature. Sir James Hall has discovered an interesting fact. Some minerals if cooled rapidly after fusion become a vitreous substance, more easily fusible than the original sub- stances; but if cooled slowly they approximate to the original substance in appearance and properties.