TOUGHENED GLASS

Patea Mail, Volume III, Issue 298, 23 February 1878, Page 4

TOUGHENED GLASS

By the courtesy of Air J. Evans Brown we have had an opportunity of inspecting some of the toughened glass of which so much has been heard of late, and of which an immense number of useful articles are now being made. Mr Brown has, though an American agency, obtained a selection of these toughened glass goods from Paris; including such articles as lamp globes, tumblers, &c. We have amused ourselves by experimenting with an ice cream saucer, the material of which closely resembles the well known opal-tinged glass. The saucer has been repeatedly thrown to a considerable height and allowed to fail upon the ground, it as been dashed against a wail, thrown info a grate and upon a slab of stone and used both as a cricket Dal 1 and football, all of 'which tests it defied, ami leads to the conclusion that a household stocked with such articles might set the proverbial cat at defiance. According to the various notices of M. do ia Basiie’s process which have appeared from time to time, that gentleman in the tb-st instance endeavoured to obtain his desired result by a compression of the glass while in a fluid condition, bis idea being that by some such process the cohesion of its particles could be increased. The attempts were failures, and it was then discovered that by dipping glass into oil or some similar liquid which was capable of being raised to a temperature considerably above that of boiling water, the glass was not only hardened but tempered, or, in other words its brittleness had departed. This is the process in brief, although there are many attendant conditions ■which have to bo carefully provided for, such as the temperature of the glass and the liquid bath, the nature of the ovens, ike. It has been very wisely pointed out that sheets of the toughened glass of ordinary thickness, although, capable ot immense insistence, arc not to be supposed to withstand the force of a stone deliberately aimed. A pane on’y the eighth of an inch thick has been found capable of bearing a maids weight, and lamp chimnies will withstand the direct contact of flame without breakage. If the glass does break it invariably shivers into fragments, and it may be stated that it cannot be cut. with a diamond like ordinary glass. It will, however, be evident that articles of glass prepared by such a process present advantages which would effectually cover any minor defects.—Lyttelton Times.