NEW SOURCES OF LIGHT. 321 



Mme. Curie, speculating on the matter, conjectured that all space is 

 continually traversed by rays analogous to Eontgen rays, but far more 

 penetrating, and not capable of being absorbed by certain elements 

 of high atomic weight, such as uranium and thorium. Becquerel, 

 reflecting on the marvellous spontaneous emission of light, said: "If 

 it can be proved that the luminosity causes no loss of energy, the state 

 of the uranium is like that of a magnet which has been produced by an 

 expenditure of energy and retains it indefinitely, maintaining around 

 it a field in which transformation of energy can be effected; but the 

 photographic reductions and the excitation of phosphorescence require 

 an expenditure of energy, of which the source can only be in the radio- 

 active substances." Somewhat later, Becquerel hazarded the opinion 

 that the radiation is composed at least in part of cathodic rays; but 

 these have been proved to be material, hence the induced activity must 

 be caused by material particles impinging upon the substances excited. 

 This materialistic theory seems to be confirmed by the results of in- 

 genious experiments made by Mme. and M. Curie; they placed a 

 sensitive plate beneath a salt of radium supported on a slab of lead, 

 in the vicinity of an electro-magnet. Under these conditions, when 

 the current was passing, the rays emitted were bent in curved lines 

 upon the sensitive plate, making impressions. 



It may be objected, says a French writer, that the materialistic 

 theory requires us to admit actual loss of particles of matter, never- 

 theless the charges are so feeble that the most intense radiation yet 

 observed would require millions of years for the removal of one 

 milligram of substance. 



While writing these lines, we have news of experiments that seem to 

 throw doubt on the elementary character of these radio-active bodies; 

 Bela von Lengyel, of Budapest, claims to have prepared the so-called 

 'radium' synthetically. By fusing with the heat of electricity uranium 

 nitrate mixed with a small percentage of barium nitrate, and treating 

 the mass with acids, he obtained a substance that gives out actinic rays, 

 Eontgen rays, excites platino-cyanid screens and causes air to conduct 

 electricity; in short, the Hungarian chemist gets material possessing 

 all the properties characteristic of the 'element' announced by Mme. 

 Curie. 



Admitting that radio-active bodies can be manufactured to order, 

 are we any nearer explaining their mysterious powers? 



Speculations as to the future history and applications of these 

 wonder-working bodies press upon even the dullest imagination; if a 

 few grams of earth-born material, containing only a small percentage 

 of the active body, emit light enough to affect the human eye and a 

 photographic plate, as well as rays that penetrate with X-ray power, 

 what degree of luminosity, of actinism and of Eontgenism (if the term 



VOL. LVII.— 21 



