WRESTING THE SECRETS OF JENA GLASS.

Pukekohe & Waiuku Times, Volume 5, Issue 154, 10 March 1916, Page 1 (Supplement)

WRESTING THE SECRETS OF JENA GLASS.

(The Germans have had the monopoly of making extraordinary glass, including glass which cures

uiaeases, but our men of science are now engaged on this work.)

Already we are well on the way towards solving the secrets of the manu-

facture of Jena glass, says an English paper. Germany has practically monopolled the manufacture of certain kinds of glass possessing very remarkable qualities, and when the German supplies were cut off many important

industries in this country were so seriously affected that our men of science were induced to undertake special investigations.

All the glass used in miners' safety lamps, for instance, was of German make, this glass possessing remarkable toughness and non-liability to cracking by heat or blows. As the result of investigations carried on at the Leeds University, we are now making this

A sporinl commit too has been working; in London with tlir> object of solving the secrets of manufacture of peculiar glass. The curious fact was that although chemical analysis gave the exact constituent'?, when the materials were mixed quite different glasses were formed, but now many of hto actual qualities are being produced. Few people are aware of the remarkable kmds of glass which are made today. Whjl'e the making of glass is carried on in all countries, in every case the best optical lenses are made from that special kind called Jena glass. It is not at all an easy matter to provide a lens which will transmit pure white light. Sir Isaac Newton thought it would b e impossible to make such a lens; but Pollard made one by combining a piece of flmt-glass and a piece of crojsvn glass. The remedy was not perfect, but it was the only one possible until Jena glass was discovered. Tl.e first experiments to form a new glass for optical purposes were made by an English clergyman, the Rev. Vernon Harcourt, in 1834, the investigations being carried on for 23 years. All sorts of experiments were made by alloying different glasses, and introducing new ingredients. About thirty years ago the Prussian Government provided Professor Ernst Abb e and Pr. Otto Scliott with resources to make investigations in the science and art of glass-making. These investigators began their experiments at 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 free from colour, and yet was almost perfectly transparent. At present researches ar e being made to make a peculiar glass which will trnsmif only one co'o'.ir.

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 microscope. By the aid of this remarkable glass an object measuring only l-T50.000.000 part of an inch in length may be brought to view indirectly. The infinitesimally small size of such an object is l>eyond the powers of imagination. Some of the Jena glass is annealed by heating, and is then slowly cooled for a month. The result is a glass which never alters its domensions at ordinary temooratures.

Another of the new glasses is quite indifferent to ordinary changes of temperature, that is, it will not crack on sudden heating. A vessel made of such glass can be filled with jce, and put on a gas flame without cracking, moreover such glass is practically transparent.

Another glass will resist the action of hot corrosive liquids. Still another kind of glass provides a light of n peculiar kind, very useful in treating certain skin diseases. The ravs from tin's g!as« cause severe irritation to the eyes and skin, but very quick'y destroy disease germ*, acting much the same as radium. Glasses are now made which are quite free from brittleness and oorrodiability, and yet of a strength which is practically equal to that of a metal.