Glass, packing. This subject will be considered under the general head of Packing.
Writing on glass may be performed by a piece of French chalk or crayons prepared for the purpose; or even with a common pen held nearly perpendicular. Indian ink, or, when the article will be exposed to damp, shell-lac ink or varnish, thickened with a little Vermillion, or lampblack, is best adapted to this purpose. Common ink is not sufficiently opaque.
Glass, to prevent the cracking of, by boiling water. When new, all glass and earthenware should be placed in cold water in a saucepan, and after some hours the saucepan containing the vessel or vessels, should be placed over the fire, until the water reaches the boiling point.
Glass. This term was applied by the older chemists to various substances to which a vitreous appearance has been given by heat. Thus we have ‘GLASS OF ANTIMONY,’ ‘GLASS OF BORAX,’ &c. It is now obsolete.
Glass, Iridescent. The inventor of the process by which this beautiful variety of glass is made is M Clémandot.
The ‘Chemical News’ states that the principle observed in its manufacture consists in submitting the glass articles to the action of dilute hydrochloric, sulphuric, or other acid, under a pressure of from two to six atmospheres. M Clémandot claims to be able to imitate the nacreous films which are seen on ancient glass which has been exposed to combined atmospheric influences for thousands of years.
Glass, Pow′dered. Syn. Vitrum pulverisatum, L. Prep. Heat the glass red hot, throw it into cold water, dry, and powder it. Used to filter acids, and glued upon paper as a polishing powder; also to wear down corns upon the feet, after the feet have been well soaked, and dried.
Glass, Sol′uble. Syn. Water glass; Vitrum solubile, L. An impure alkaline silicate. Prep. Silica, 1 part; carbonate of potassium or of sodium, 2 parts; fused together.
Carbonate of sodium (dry), 54 parts; carbonate of potassium (dry), 70 parts; silica, 192 parts; as last. Soluble in boiling water, yielding a fine, transparent, semi-elastic varnish.
Carbonate of potassium (dry), 10 parts; powdered quartz (or sand free from iron and alumina), 15 parts; charcoal 1 part; fused together. Soluble in 5 or 6 times its weight of boiling water; and the filtered solution, evaporated to dryness, yields a transparent glass, permanent in the air.