GERMAN GLASS SECRETS.

Manawatu Herald, Volume XXXVIII, Issue 1569, 27 June 1916, Page 4

GERMAN GLASS SECRETS.

THE MYSTERY OF JENA-CKY-STA L M ETA L ST RENGTI f.

Already we are well on the way towards solving tin 1 secrets of the manufacture of dona Glass, writes a. British journalist. Germany has practically monopolised Hit! manufacture of certain kinds of glass possessing very remai’kable qualities, and when the German supplies wore cut off many Important industries in Great Britain wer(> so seriously affected that our men of science were induced to undertake special investigations. All the glass used in miners' safely lamps, for instance, was of German make, this glass possessing remarkable toughness and non-liabi-lity to (‘racking by heat or blows. As the result of investigations carried on at the Leeds University, we arc now making this glass. SOLVING THE SECRETS. A special committee has been working in London with the object of solving the secrets of manufacture of peculiar glass. The curious fact was that although chemical analysis gave the exact constituents, when the materials were mixed quite different glasses were formed, but now many of the actual qualities are being produced. Few people are aware of the remarkable kinds of glass which are made to-day. While the making of glass is carried on in all countries, in every case the best optical lenses arc made from that special kind called Jena, glass. It is not at all an easy matter to provide a lens which will transmit pure while light. Sir Isaac Newton thought; it would he impossible to make such a lens ; hut Dollard made one by combining a piece of flint-glass and a piece of crown glass. The remedy was not perfect, but it was (he only one possible until Jena, glass was discovered.

The first, experiment to form :i new glass for 1 purposes were made by ;in English clergyman, the Rev. Vernon Jlarcourl, in 18‘M, tlie investiga I ions being carried on for (wenty-five years. All sorts of experiments were mode by alloying different, glosses nnd introducing new ingredients. About thirty yours ugo the Prussian Government provided Professor Ernst Abhe und Dr Ot.to Schott with resources to make investigulions in the science und urt of gluss-making. These investigators began their experiments in the town of Jena, and as the result of many long and costly experiments they produced some very extraordinary glasses —hundreds of kinds. The main discovery, so far as photographers are concerned, was that of a glass which was almost perfectly tree from colour, and yet was almost perfectly transparent. At present researches are being made to make a, peculiar glass which will transmit only one colour. COOLED FOR A MONTH. One of the most, noteworthy discoveries at Jena has been that of a, glass which is utilised in making microscopic lenses. .By these lenses it is possible to photograph particles otherwise invisible to the most powerful microseope. By the aid of this remarkable glass an object measuring ouly 1-735,000 th part of an inch in length may he brought to view indirectly. The infinitesimally small size of such an object is beyond the power of imagination. Home of the Jena glass is annealed by heating, and is then slowly cooled for a. month. The, resalt is a glass which never alters its dimensions at ordinary temperature. Another of the new glasses is quite indifferent to ordinary changes

of temperature, that is, it will not crack on sudden healing. A vessel made of such glass can be filled with ice and put on a gas flame without cracking; more over, such a glass is practically transparent. Another glass will resist, the action of hot corrosive liquids. Still another kind of glass provides a light of a peculiar kind, very useful in treating certain skin diseases. The rays from this glass cause severe irritation to the eyes and skin, but very quickly destroys disease germs, acting much the same as radium. Glasses are now made which are quite free from brittleness and corrodiability, and yet of a strength which is practically equal to that of a metal.