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.

    24/464 (page 4)
    Flint. Phofpho- rus. Flint at a burning giafs. Melted with Lime Vitrifica¬ tion with Sails. E a rths and Stones. mierofcope, appear to be globules of vitrified mat-* ter: A chemical examination difcovers that they con¬ tain more of the Iron than of the Flint, changed into a kind of glaffy Scoria (a).—-Two Flints ftruck again ft one another, pro] eft no vifible fpark ; nor do the fragments broke off feem to have fuffered any change: But the Stones themfelves appear, in the dark, luminous; fome throughout the whole mafs, others only on the fide ftruck upon. The greater number of Flints I have examined is of this laft kind. Boerhaave relates, that Flint, placed in the focus of Vilette's burning fpeculum, was inftantly con¬ verted into glafs. I have had no opportunity of try¬ ing that inflrument *, but have expofed Flint to the aflion of the large burning lens of Tfchirnhaus, without being able to produce anv fuch effeft. Though Flint, however, by itfelf, abfolutely refill's that moft vehement heat, and Quick-lime by itfelf equally refills it; yet a mixture of the two runs with eafe into glafs (b). Powdered Flint, mingled with a due proportion of fixt Alcaline Salt, melts eafilyin the common fur¬ naces, fa) Sparks from Flint and Steel.'] It does not appear that the Steel is here really vitrified, or that the heat produced is lo intenfe as has been generally fuppofed. Among the particles of metal abraded by the mint, there are indeed fome globular ones which have evidently been melted: but the magnet fti 11 attra&s them j a mark that they are not fcorified, but continue perfectly metallic. The fufion of fmall mole- cube of Steel does not require any very extraordinary heat: it fine Steel-wire be held barely in the flame of a candle, the end will melt, and form a little ball like thofe obtained in the experiment of flu iking fire with Flint. (h) Vitrification of Flint.] Of all the faline matters that have been tried in xompofition with Flint, fixt alcalies moft effectually promote its .vitrification : two parts of the Alcali and three of Flint, urged with a Strong fire, form a ptrfecft glafs. Borax, by vehemence of heat, may be made to vitrify twice its weight, and even more j but the compound fcarcely proves tranfparent, unlefs the Borax be equal in quantity to the Flint: a fmall addition of Alcaline Salt to * this mixture promotes both the fufion and tranfparency : the glaffes made with Borax, or with Borax ami a little Alcali, prove rather harder than thole with the Alcaline Salt alone-—Common Salt, Sal mirabile and Sandiver, are remarkably indifpofed to vitrify with Flint, though even in twice or thrice the quantity of the Stone : nor do they, in any proportions, form with it a. pellucid glafs.