Flann O’Brien’s fictional scientist and savant De Selby conceived a theory that darkness, far from being the absence of light, is really an accumulation of minutely small black corpuscles. I had attributed this wonderful notion to O’Brien’s joyful surrealism, but I learn from Pascal Richet, in A Natural History of Time, that in 1896 the physicist Gustave Le Bon actually announced to the Academy of Science in Paris the discovery of black light. Maybe the voraciously curious O’Brien had come across this absurdity – a forgotten footnote in scientific history. There was no shortage of similar oddities at the end of the nineteenth century, following the discovery of X-rays – those mysterious entities that could pass through flesh itself. N-rays, “a new type of radiation”, for example, were visible particularly to their discoverer, an otherwise respectable professor from Nancy called René Blondlot. Like radium, they emitted radiant matter. He said of them: “The observer should accustom himself to look at the screen just as a painter, and in particular an ‘impressionist’ painter, would look at a landscape. To attain this requires some practice . . . some people, in fact, never succeed”. Indeed they didn’t, for N-rays were a fiction.
more from the TLS here.