Volume 2

Applied chemistry; in manufactures, arts, and domestic economy / Edited by Edward Andrew Parnell.

  • Parnell, Edward A. (Edward Andrew)
Date:
1844
Catalogue details

Licence: Public Domain Mark

Credit: Applied chemistry; in manufactures, arts, and domestic economy / Edited by Edward Andrew Parnell. Source: Wellcome Collection.

    79/490 (page 61)
    making broad-glass ; being generally fritted, before they are introduced into the glass-pots, in arches at¬ tached to the principal furnace. As the mixture always contains a very small relative proportion of the alkaline ingredient, its vitrification requires a very high temperature; but it is generally complete in eighteen or twenty hours, and after the undis¬ solved matter has subsided, the sandiver been skimmed off, and the glass become cooled down to the blow¬ ing consistency, the mass may be worked up into bottles. To form a wine-bottle, a sufficient quantity of the melted glass is collected in a pear-shaped ball on the end of the blowing iron, and the ball is then introduced into an open cast-iron or brass mould, the tube being held vertically. The blower imme¬ diately closes the mould by pressing a pedal-lever with his foot, and blows the glass into the form of the mould. By withdrawing his foot from the lever, the blower opens the mould and then lifts up the bottle, which is immediately detached from the tube by applying a cold iron to the neck or mouth-ring. The bottle is lastly annealed in the ordinary manner. The earth resulting from the disintegration of ba¬ saltic rocks, which may be obtained in the valleys of all basaltic countries, has been successfully used in the manufacture of bottle-glass; but is now entirely abandoned, I believe, from the difficulty of procuring the earth of anything approaching uniform compo¬ sition. It generally contains three or four per cent, of soda, about half its weight of silicic acid, and one-fifth its weight of oxide of iron ; the remainder consists of lime and alumina. A mixture of equal