588 Scientific Intelligence. 



val and the y-rays only at the high temperature. This experi- 

 ment agreed with subsequent tests in showing that neither the 

 /3- nor the y-rays of radium C are affected hj high temperatures. 

 Under all conditions both radiations decayed exponentially, fall- 

 ing to half value in about 19 '4 minutes. 



Experiments with the active deposit gave the following results. 

 The /3-ray activity decayed at the theoretical rate both at 1150° C. 

 and at 200° C, and the amount of activity was unaltered by the 

 temperature changes. Of the 35 points determined, 2 were 

 within 3 per cent, 2 within 2 per cent, and 31 were within 1 

 per cent of the theoretical values. In like manner, the y-ray 

 points fell on a smooth curve without abnormalities at the high 

 temperatures ; 29 points agreed within 1 per cent with the theo- 

 retical values, and the remaining 4 points within 2*5 per cent. 



The rest of the investigation deals with the volatilization of 

 radium C inside quartz tubes, with experiments on the radium 

 emanation, and with the partition of homogeneously distributed 

 activity. The conclusions drawn by Russell from the entire 

 research may now be quoted. 



" (a) The effect of temperature upon the rate of decay, and 

 the amount of /3- and y-ray activity, of radium emanation, active 

 deposit, and radium C have been investigated." "The results 

 are entirely negative." 



" (b) Radium B and radium C, and very probably radium A, 

 may be completely volatilised inside sealed quartz tubes at a tem- 

 perature of 650°." " Radium B commences to volatilise at room 

 temperatures." 



" (c) All abnormalities of activity of /3-rays obtained by pre- 

 vious authors, and by the author of this paper, can be completely 

 explained on two simple grounds, a change of distribution and a 

 change of partition, of radium C inside quartz tubes, produced by 

 changes of temperature." — Proc. Roy. 80c, Ixxxvi, p. 240, Feb. 

 1912. h. s. u. 



6. Das magnetische Spektrum der fi-Strahlen des Thoriums. — 

 The investigation of the /3-ra3 r s from mesothorium 2 and its disinte- 

 gration products has been successfully continued by von Baeyer, 

 Hahx and Meitner. The advance is due primarily to an im- 

 proved process of electrolytic deposition, devised by Meitner, 

 which makes it possible to obtain very fine wires of higher activ- 

 ity and consequently to take much sharper photographs of the 

 magnetic spectra than formerly. 



A strong preparation of mesothorium, which had been freed 

 from radio-thorium about a day earlier, was used in the electro- 

 lytic process. Only mesothorium 2 and a trace of the newly- 

 formed radio-thorium were deposited on the silver cathode. The 

 negatives were taken in the same manner as for the /?-rays of 

 radium (see this Journal, vol. xxxiii, page 281). In general, the 

 deviating field amounted to 138 gauss. The time of exposure 

 was one-half hour in the case of a wire which was o-l mm in diam- 

 eter and which was covered with mesothorium 2 having an activ- 



