218 History of Luminescence 



Naturalists know of a large number of substances, particularly varieties of 

 fluorspar and Ca phosphate, which possess for some time their lumi- 

 nous faculty after being taken from the earth, but they finally lose it. 

 It is infinitely probable that the loss of this property is to be attributed 

 to a change in the grouping of the particles produced by the action of 

 solar light or perhaps by variation in temperature. . . . One sees then 

 that the phenomena of phosphorescence can bind together the relations 

 between all the imponderable agents which very probably derive from 

 one and the same cause diversely modified. 



By the time the next great work (3 v.) appeared, Traite d'Elec- 

 tricite et Magnetisme, by A. C. Becquerel and his son, Edmond 

 Becquerel, in 1855-1856, the idea that the light of marine organisms 

 was electrical in origin is not mentioned. There is merely a thirty- 

 page section on " Effets Lumineux " of electricity. 



The interest in luminescence of Becquerel senior was magnified 

 many times in the work of his son, Edmond Becquerel (1820-1891) , 

 who published several papers and two books (see titles in fig. 20) on 

 luminescences of various kinds. One was a reprinting of three mono- 

 graphs, Recherches sur divers Effets Lumineux qui Resaltent de 

 I' Action de la Lumiere sur les Corps (Paris, 1859), which had 

 been presented as three -° Memoires to the French Academy of Sci- 

 ences in 1857-1858, and printed in the Annales de Chimie et de 

 Physique in 1859. The second book was the monumental La 

 Lumiere, ses Causes et ses Effects (Paris, 1867) in two volumes. 

 The first volume of 426 pages deals entirely wath light emission, the 

 second with photochemical action. Although incandescences are con- 

 sidered, the first volume is so largely concerned with phosphores- 

 cence resulting from the action of light, electric sparks, gentle heat- 

 ing, and mechanical means that it is fundamentally a book on lumi- 

 nescence. A final section of thirteen pages treats briefly of the 

 " Effets Lumineux Produits pars les Corps Organises," both vege- 

 table and animal. The older work on luminous wood, fish, and flesh 

 was mentioned and the remark made that (p. 415) " these effects 

 cannot be explained except by a sort of decomposition, by virtue of 

 which organic matter is burned with oxygen in a slow combustion 

 that is the cause of the light emitted." Becquerel rightly attributed 

 the phosphorescence of the sea to the minute forms living therein, 

 but it is surprising to find that as late as 1867, the true origin of the 

 light from phosphorescent wood or luminous fish and flesh was 

 unknown to him. 



Becquerel's work on inorganic phosphorescence dealt with every 



^'"A fourth monograph was published in the Ann. de Chim. et de Physique (ser. 3) 

 62: 5-100. 1861. 



