The Nineteenth Century 217 



could be due to animalcules and to " an organic material intimately 

 combined or mixed with the water, analogous to that which covers 

 herring and other fish." A proof of this idea came from the fact 

 that the luminous material on fish only appears in a certain state of 

 decomposition preceding putrefaction, when it disappears, and the 

 sea water also loses its phosphorescence on standing for some time. 

 Becquerel believed that in lampyrids 



phosphorescence is the result of a chemical action under the control of 

 the animal but in certain inferior animals (infusories et annelides) the 

 production of light so resembled a discharge of electricity that Ehren- 

 berg did not hesitate to establish their identity and he is certain that the 

 light does not come from a secretion but is a spontaneous act of the 

 animal, manifest on irritation by chemical or mechanical means. 



Just as an electric torpedo requires a certain time for recovery after 

 several discharges, so also do these small organisms after they have 

 been agitated for some time. Becquerel considered it remarkable 

 that the light should be so great when the organisms that produce it 

 are so small. 



As a student of electricity, it is not surprising to find that A. C. 

 Becquerel's explanation of inorganic luminous phenomena relied 

 on the ultimate units of electricity in matter. It is quite possible 

 to read into his statements the modern concept of an electron dis- 

 placed from its position of equilibrium by absorption of energy, 

 with the emission of light upon its return. His point of view is 

 expressed in the conclusions of the section " De la Phosphorescence " 

 in the Traite de Physique, etc. (1844) . Becquerel believed that any 

 type of luminescence might appear 



whenever the particles of bodies (particules des corps) lose their natural 

 position of equilibrium from any cause whatever. Under these circum- 

 stances, the equilibrium of electricities which are associated with bodies 

 is likewise disturbed and their recomposition can give rise to visible 

 light if a certain amount of time is taken to effect the change. 



If the " recomposition " is too rapid, no light appears. Such is the 

 case in metals which are never phosphorescent. Becquerel held that 

 light causes phosphorescence by acting on the electricities associated 

 with the particles, again changing their position of equilibrium, 

 rather than by acting directly on the particles themselves. As a 

 visible example of the displacement, he cited the fact that when 

 fluorspar is subject to the electric light (a spark discharge) , certain 

 parts of the crystal become colored, and these colored regions are 

 also the parts which are luminous on sight heating. He continued: 



