THE interesting list of substances mentioned in to-day's review in NATURE of a paper on the subject of the above phenomenon, mentioning as substances in which it is conspicuous, cane-sugar, saccharin, hippuric acid, and some still more complex organic bodies, might lead one to suppose that only substances of an organic nature, in a crystalline state exhibit the kind of triboluminescence seen as a flash of light when a crystal of such substances is crushed between two glasses. But this is not quite exclusively the case, because crystals of uranium-nitrate, and perhaps other crystallised salts of uranium, emit a very bright greenish-yellow flash when pressed to pieces between glass plates. The property seems permanent in these crystals, and it is also apparently independent in them of chemical impurities, since any crystallised sample of the nitrate, as far as I have tried, shows the light flash very strongly, without any apparent loss of brightness by long keeping.

Affiliations

1. Observatory House, Slough, April 27.

   • A. S. HERSCHEL

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Publication history

DOI

https://doi.org/10.1038/060029b0

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