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Toughened Glass

THE manufacture of glass that will stand with impunity a blow or fall which would shatter to pieces any vessel made in the ordinary manner, has lately been carried to great perfection; the product being of such a tough nature that its employment is being extended to services where glass, as ordinarily known, would be quite useless. The process by which these advantages are gained consists merely in dipping the hot glass as it comes from the hands of the workman in a tempering bath of oil. To show how effective this treatment is, we may mention that the following experiment was lately made. A quantity of ordinary drinking glasses were placed in a basket with the same number of tempered glasses. The basket was then violently shaken, with the result that the untempered glasses were smashed to atoms, whilst the others remained quite intact. The process is applicable to lamp glasses and all other vessels which are so frequently broken, the expense of the new method not contributing much to the price of the finished article.

But by far the most novel application of the new material is its employment for railway sleepers, to take the place of those of wood, which are of course liable to rot and decay, and will only therefore last a limited number of years. Glass sleepers, on the other hand, are practically imperishable, and from experiments made as to their non-brittle qualities, they seem eminently adapted for railway work. We quote the following results of tests lately made with the new sleepers:- "A falling weight of 9 cwt. dropped from a crane upon a glass plate, 9 inches square and 1 1/8 inch thick, laid upon gravel ballast 9 inches deep, with a wood cushion 1/8 of an inch in thickness between the glass and the rail:- Fall 3 feet 0 inches without effect. Fall 5 feet 6 inches without effect. Fall 7 feet 0 inches without effect. Fall 12 feet 6 inches without effect. Fall 15 feet 0 inches without effect. Fall 17 feet 6 inches without effect. Fall 20 feet 0 inches without effect.

At this point the rail broke, and as the crane could not elevate the weight to a greater height, and a heavier weight was not available, a smaller section of rail was substituted, when the glass succumbed to a second application of the 9 cwt. dropped from a height of 20 feet.