268 POPULAR SCIENCE MONTHLY. 



In the rather simple working up of the raw material containing 

 radium, the treatment of barium has in the main been followed. Sub- 

 sequently, the utilization of certain differences in solubility has per- 

 mitted fractional crystallization and we have thus learned of a special 

 spectrum of radium. But it is questionable whether the spectrum 

 reaction can claim a decisive weight. For a substance, which in so 

 minute proportions has been extracted from so complex a material as 

 the residuals of Joachimsthal, the spectrum might readily prove de- 

 ceptive. There seems to be very little correspondence between the 

 spark-spectrum for radium obtained by Demarcay, and the flame 

 spectrum described by F. Giesel, while the reddish-orange lines in the 

 radium bromide spectrum, as well as the red coloration which this 

 substance imparts to the flame, make it not impossible that some 

 alkaline earths may have remained in the final residue examined. Be- 

 sides, no radium compounds have been sufficiently investigated, nor have 

 any chemical reactions been detected specifically peculiar to radium. 

 The determination of its atomic weight has been decisive in recognizing 

 radium as a distinct element, especially as this atomic weight was 

 found to be exceptionally high. 



Badium lead has been examined chemically more thoroughly, and 

 yet no noteworthy differences have been discovered between its reac- 

 tions and those of common lead. Only a great difference in atomic 

 weight seemed to exist. The atomic weight of radiolead was deter- 

 mined by ascertaining the amount of sulphuric acid in its sulphate. 

 It was found to contain 41.85 per cent, of S0 4 , while lead sulphate 

 contains only 31.71 per cent. 



Assuming that radiolead is quadrivalent like thorium and uranium, 

 its atomic weight from the above analysis would be 260.2, that of 

 lead only 206.9. But this determination seems of doubtful correctness, 

 because the sulphate obtained has not been heated to a beginning red- 

 heat, but has only been dried to 400-420 degrees. At so low a tempera- 

 ture experience has shown it is impossible to remove all adherent sul- 

 phuric acid, so that it is not strange that a higher per cent, of sul- 

 phuric acid remained. The atomic weight of radiolead can not be 

 deduced from such determinations. Also the supposed discovery of 

 other elements (such as the much hunted for ekamanganese of Men- 

 delejef) can not be established upon the result of such faulty deter- 

 minations. 



Indeed the chemical researches made can not be considered suffi- 

 cient, however much we may admire the other researches made on the 

 radioactivity of matter. Even the results obtained by fractioning can 

 only be used with extreme caution, because they may lead easily to false 

 conclusions. When the discovery of spectrum analysis had excited the 

 scientific world as it is to-day excited by that of radioactivity, it was 



