Inventions in the Century

by William Henry Doolittle

Mr. Gaffield also extended his experiments to ascertain the power of different coloured glasses to transmit the actinic or chemical rays, and found that blue would transmit the most and red and orange the least.

Others proceeded on lines of investigation in ascertaining the best materials to be employed in glass-making in producing the clearest and most permanent uncoloured light; the best coloured lights for desired purposes; glasses having the best effects on the growth of plants; and the best class for refracting, dispersing and transmitting both natural lights and those great modern artificial lights, gas and electricity.

Another illustration of modern scientific investigation and success in glass-making materials is seen at the celebrated German glass works at Jena under the management of Professors Ernst Abbe and Dr. Schott, commenced in 1881. They, too, found that many substances had each its own peculiar effect in the refraction and dispersion of light, and introduced no fewer than twenty-eight new substances in glass making. Their special work was the production of glass for the finest scientific and optical purposes, and the highest grades of commercial glass. They have originated over one hundred new kinds of glass. Their lenses for telescopes and microscopes and photographic cameras, and glass and prisms, and for all chemical and other scientific work, have a worldwide reputation.

So that in materials of composition the old days in which there were substantially but two varieties of glass—the old-fashioned standard crown, and flint glass—have passed away.

Methods.—The revolution in the production of glass has been greatly aided also by new methods of treatment of the old as well as the new materials. For instance, the application of the Siemens regenerative furnace, already alluded to in referring to pottery, in place of old-fashioned kilns, and by which the amount of smoke is greatly diminished, fuel saved, and the colour of the glass improved. Pots are used containing the materials to be melted and not heated in the presence of the burning fuel, but by the heated gases in separate compartments.

Another process is that of M. de la Bastie, added to by others, of toughening glass by plunging it while hot and pasty and after it has been shaped, annealed, and reheated, into a bath of grease, whereby the rapid cooling and the grease changes its molecular condition so that it is less dense, resists breaking to a greater degree, and presents no sharp edges when broken.

Another process is that of making plate glass by the cylinder process—rolling it into large sheets.

Other processes are those for producing hollow ware by pressing in moulds; for decorating; for surface enamelling of sheet glass whereby beautiful lace patterns are transferred from the woven or netted fabric itself by using it as a stencil to distribute upon the surface the pulverised enamel, which is afterwards burned on; of producing iridescent glass in which is exhibited the lights and shadows of delicate soap bubble colours by the throwing against the surface of hydrochloric acid under pressure, or the fumes of other materials volatilised in a reheating furnace.

Then there is Dode’s process for platinising glass, by which a reflecting mirror is produced without silvering or otherwise coating its back, by first applying a thin coating of platinic choride mixed with an oil to the surface of the glass and heating the same, by which the mirror reflects from its front face. The platinum film is so thin that the pencil and hand of a draughtsman may be seen through it, the object to be copied being seen by reflection.

Again there is the process of making glass wool or silk—which is glass drawn out into such extremely fine threads that it may be used for all purposes of silk threads in the making of fabrics for decorative purposes and in some more useful purposes, such as the filtration of water and other liquids.