photogenn.

1814 Philos. Mag. 43 22 That element which appears at the negative surface, and exhibits the most brilliant light, may be called the generator of light, or photogen.

1858 Catal. 10th Exhib. Inventions in Jrnl. Soc. Arts 6 App. I. 31 No. 166. Patent Photogen, or Light Generator, to be used for taking Photographs at Night.

1896 Cambr. Nat. Hist. II. 296 In Tomopteris there is..a brightly-coloured spherical organ, which for a long time was regarded as an eye, but from its structure appears to be a ‘photogen’.

1906 Ann. Rep. Smithsonian Inst. 1905 356 The further our knowledge..is extended the more probable appears the idea that within the cell is a hypothetical substance, ‘photogen’, which has the power of producing light in the presence of free oxygen.

1979 G. Macdonald Camera x. 143 Pyrotechnic compounds were in use in the 1850s and flashlit portraits were made in studios used a ‘photogen’ mixture which burned in a glass lantern for some fifteen seconds.

1990 Japan Econ. Jrnl. (Nexis) 27 Jan. 14 Sony succeeded in developing the system with a single semiconductor laser chip that can modulate two photogens at one time.

1856 Times 26 Nov. 3/5 A manufactory, particularly of photogene or paraffine.

1861 A. Gesner Pract. Treat. Coal iv. 61 Wagenman applied himself to the oils derivable from turf, brown coal, and bituminous slate, from which he obtained photogen, solar oil, and paraffin.

1880 Pall Mall Gaz. 10 May 12/1 The American raw petroleum gave about two-thirds of its weight of photogen, while the Russian only gives about one-third photogen, but a greater proportion of fatty oils.

1891 R. Routledge Discov. & Inventions 19th Cent. (ed. 8) 630 Sometimes they are mixed together, and sent into the market as illuminating oils under various names, such as ‘photogen’, or ‘solar oil’, &c.