RADIOACTIVITY AND MATTER. 





RADIOACTIVITY AND MATTER* 



By CLEMENS WINKLER. 



HP HE discovery of radioactivity has opened to physical and probably 

 -*- also to chemical research a field of extraordinary and peculiar 

 promise. We seem to have a source of energy which flows spontane- 

 ously for unlimited time without tangible indication of its source; 

 effects of energy are exhibited which neither in essence nor in phe- 

 nomena resemble those previously known; substances are presented 

 which seem to be of an entirely new kind, though they resemble our 

 oldest and best-known elements so closely as to make their distinction 

 difficult. The most prominent of these substances is radium, which, 

 in the opinion of its discoverers, may be considered a new chemical 

 element and which has been recognized as such by the International 

 Atomic Weight Committee by giving it a place in their table of 

 atomic weights for 1904. 



Much more indefinite are the relations of the other radioactive 

 substances thus far made known. The existence of polonium, dis- 

 covered by P. and S. Curie, was for a time considered dubious, but 

 seems to awake to new life in the radiotellurium of W. Marckwald. 

 On radiolead voluminous researches have appeared which are especially 

 noteworthy in chemical respects, still they do not yet authorize us to 

 recognize a new element with certaint3 r , even if we disregard the ob- 

 jections raised by F. Giesel against these researches. The same may 

 be said of the actinium of A. Debierne and other radioactive substances, 

 such as are supposed to have been detected in the earths of the cerium 

 and yttrium group. 



This uncertainty may be understood if we consider that for the 

 researches thus far made only very small amounts of pure or merely 

 enriched materials have been available, which has made the chemical 

 investigation very difficult. The great fascination of tracing the ob- 

 served phenomena of radioactivity by means of the sensitive photo- 

 graphic plate, the electroscope and the phosphorescent screen had quite 

 naturally made the investigation of the chemical behavior of the sub- 

 stances in question a secondary matter which, while it has not been 

 entirely overlooked, yet has not received that degree of attention that 

 formerly was bestowed on the determination of the characteristic prop- 

 erties of newly discovered elements. 



* Translated from Berichte der Deatschen Chemischen Gesellschaft. The 

 author, best known by this discovery of the rare element Germanium, died Oct. 

 8, 1904, at Dresden.— G. D. H. 



