New Inventions

> For some years Dr. Irving Langmuir of General Electric Co. has investigated the properties of monomolecular layers-- that is, oil films, one molecule thick. He finds that in such layers molecules all stand on end, lined up in the same direction; that layers any number of molecules thick could be built up on a pane of glass by repeatedly dipping it in water covered with a monomolecular film. All this, however, came under the head of "pure-science" research.

Pure science gave way to practical technology when one of Dr. Langmuir's coworkers, Dr. Katharine Burr Blodgett, found that a layer of transparent liquid soap, with a thickness of one-quarter the average wavelength of white light (about 4/1,000,000 in.), made the glass to all intents and purposes invisible. Reason: glass is visible because of the light reflected from its surface; with a soap film there are two reflections, one from the glass and one from the soap; by spacing the two surfaces properly it is possible to get the "crest" of a light wave bouncing off the glass to coincide with the "trough" of the wave bouncing off the soap so that the two cancel out. It appeared that a film dried as a varnish four millionths of an inch thick was just right to kill all reflections. Yet the film-on-glass combination is a highly efficient transmitter of light, for some 99% of the light which reaches it passes on through.

Some stores and showrooms have "invisible glass" windows, but these are parabolic panes such that reflections are bent downward and absorbed in a baffle of black cloth. Glass such as Katharine Blodgett's, which actually obliterates reflection at its surface, could be used as an invisible protection for paintings in galleries and museums. Other possible uses: automobile windshields, shop windows, show cases, cameras, spectacles, telescopes, field glasses.

Only a day after Katharine Blodgett announced her discovery last week, Drs. C. Hawley Cartwright and Arthur Francis Turner of Massachusetts Institute of Technology reported at a physics meeting in Washington that they had also produced invisible glass, using a similar principle. Their reflection-absorbing varnish, however, is deposited on the glass by condensing the vapor of metallic fluorides.

>Compressed air is a ubiquitous tool in industry and transportation. Last fortnight a 35-year-old businessman of Phoenix, Ariz., L. V. Jones, convinced scientists at California Institute of Technology that he had found a way of compressing air more efficiently and cheaply than ever before. In practice, the compression of air generates heat which must be drawn off by water jackets. In the Jones device, there are no water jackets. The heat of the compressed air is removed by circulating oil and returned to the pump where it furnishes accessory driving energy. The same principle, Mr. Jones declared last week, could be used to increase the efficiency of superchargers on airplane engines. He has applied for a patent.

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