524 M. Becqucrel on the Luminous Effects 



toluolc in the same relation that parabenzole does to benzole, — a 

 suggestion which becomes more probable on referring to the 

 boiling-points of these hydrocarbons — 



Benzole. Parabenzole. Toluole. Pavatoluole (?). 



80°-8 + 16°-7 = 97^^-5 103°-7 + 15°8 = 119°-5. 



The boiUng-point of 103°-7 assigned to toluole has been lately 

 confirmed ; and if on further examination the hydrocarbon boil- 

 ing at 119'^-5 should be found to be an isomer of toluole, the 

 discrepancies in the boiling-points assigned to this body will be 

 explained ; for the analysis of fractions of coal-naphtha boiling 

 between lO^" and 131° has been found by several experimenters 

 to give numbers exactly according with the formula C'"* H^. 



Now that the ordinary alcohol radicals have been detected in 

 various naphthas, it is not unreasonable to expect the occvirrence, 

 in similar products, of the radicals phenyle, toluenyle, &c., and 

 also of such hydrocarbons as methyle-phenyle, butyle-phenyle, 

 &c. :— 



Benzole. Butyle. Phenyle. Butyle-phenyle. 



C'^H^H. C8H9,CnR Ci^H^c'i'^Hs. CSH^C'^H^. 



Lincoln College, Oxford, 

 November 21st, 1859. 



LXXIX. On the Luminous Effects p-oduced by the action of 

 Light upon Bodies. By M. Eumond Becquerel*. 



SO long ago as 1842, M. E, Becquerel occupied himself with 

 researches on the action of the solar spectrum on different 

 sensitive bodies, and published several new facts with resj)ect to 

 phosphorescence by insolation. The new memoir which bears 

 the above title occupies the whole of last January's Number of the 

 Annates de Chimie et de Physique, on which account we must 

 here limit ourselves to a statement of the more important facts 

 therein contained, and to a textual reproduction of the author's 

 own conclusions. 



After having in a preliminary chapter recapitulated the several 

 facts hitherto established, and shown that the effects to which 

 the term phosphorescence is applied do not arise from chemical 

 action, but from essentially physical modifications — in short that 

 they depend upon variations of equilibrium in the molecular con- 

 dition of bodies, — M. Becquerel reviews successively the several 

 mineral and organic substances capable of becoming self-lumi- 

 nous after having been exposed for some moments either to the 

 action of diffuse solar light, or to that of rays emanating from a 

 sufficiently intense source of light. Amongst these come first the 

 * From the Bibliotheqvp Universclle, vol. xvi. p. 21. 



