Volume 1

The chemical works of Caspar Neumann ... / abridged and methodized. With large additions, containing the later discoveries and improvements made in chemistry and the arts depending thereon by William Lewis.

  • Neumann, Caspar, 1683-1737.
Date:
1773
Catalogue details

Licence: Public Domain Mark

Credit: The chemical works of Caspar Neumann ... / abridged and methodized. With large additions, containing the later discoveries and improvements made in chemistry and the arts depending thereon by William Lewis. Source: Wellcome Collection.

    26/464 (page 6)
    Flint, no mark of a faline nature *, a fomewhat larger pro- v—j portion of the Alcali changes the Flint itfelf into an apparently faline form. If powdered Flint be mixed with thrice, twice, or even equal its weight of fixt Alcaline Salt, and a mixture melted in a crucible; the mafs, though it has a vitnous appearance, proves in tafte faline and fiery, like the Alcali itfelf j and, on being expofed to the air, runs in a little time, Flint and all, into a colourlefs tranfparent liquor called Liquor filicum, or Oleum ftlicis per deliquium (e), coagnia- This liquor, on being mixed with mineral Acids, quinds°.fLl’Particukrly ^e vitriolic, inftead of effervefcing and uniformly mingling with them, as mere Alcaline Li¬ quors do, grows inftantly thick, and in fame degree folid ; as if the diffolved Flint was going to refume its original confidence. It coagulates alfo with me¬ tallic folution made in Acids; that of Corrofive fub- limate, or of Mercury in the Marine Acid excepted ; this . folution yielding with the Liquor Silicum, as with pure Alcalies, an, orange yellow Precipitate, and fcarce difcovering any tendency to become curdly. It likewife becomes confiderably thick or confident, with fome folutions of Earths in Acids, as that of Quick-lime in the marine. If loaded with the Flint, as the liquor prepared from equal parts of Flint and Alcali, it grows thick, upon danding for fome time, without any addition. The coagulum which it forrns with folutipn of Mercury in the nitrous Acid appears variegated (e) Deliquiation of Flint and Alcali.] The proportion of Alcaline Salt for obtaining with Flint either a deliquiable or a truly vitrious compound, depends greatly on the degree and continuance of the fire. A mixture of powdered Flint with an equal quantity of the Salt, if taken out of the furnace as loon as it appears melted, will liquefy by degrees upon exposure to the air : but if the fire is kept up ftrong for feveral hours, though the quantity of Salt be more than doubled, the refult will he a perfect and durable glafs ; all the fuperfluous Alcali being ditTipated by the vehemence of the heat. One part of Alcali and two of Flint have been laid to deliquiate : But this mixture requires a very ftrong fire for its fufion ; and when perfectly melted, proves a femitranfparent glafs, of confiderable hardnefs, io as freely to ftrike fire with fteel. Glafs in general is found to be harder in proportion as it contains lefs Salt.