Dr. J. A. Crowther on "J" Radiation. 727 



by Rutherford (loc. cit.), the corresponding voltages for the 

 13 rays emitted ranging from 181,000 volts to 2,102,000 volts. 

 The existence of even higher speed characteristic j3 rays is 

 indicated. Since the energy of the /3 particles is known, the 

 frequency of the exciting 7 radiation should be calculable by 

 applying the quantum relation. The paper of Ellis, just 

 referred to, indicates that the relation for the transformation 

 of 7 into j3 radiation is probably of the form E = 7*v — e, 

 where e is a constant which measures the energy required to 

 withdraw an electron from the ring emitting the (3 radiation. 

 The value of e is, however, relatively very small, so that 

 no serious error arises if the ordinary relation E = 7ii> is 

 employed. It is then quite easy to show that the frequencies 

 of the characteristic 7 radiations corresponding to the lines 

 in the ft ray spectrum tabulated by Rutherford and Robinson 

 range from 43 X 10 2 ° per sec. to 5 '15 X 10 2 ° per sec. These 

 frequencies represent characteristic radiations from radium 

 C of considerably shorter wave-length than the K and L 

 radiations for that element, which have been identified 

 among the softer 7 rays. 



Since the characteristic K and L radiations of elements of 

 lower atomic number are represented in the case of the 

 radioactive elements by soft radiations, it seems at any rate 

 possible that characteristic radiations corresponding to the 

 high frequency rays might be excited in elements of lower 

 atomic number under suitable circumstances. It is, of course, 

 possible that the ring systems emitting this high frequency 

 radiation, and which must be very close to. or perhaps even 

 within, the nucleus of the atom, are not present. in elements 

 of low atomic number. This can only be decided on experi- 

 mental evidence. If, however, such radiation is possible, its 

 frequency for any given element should be deducible, at any 

 rate approximately, by applying the law that the frequency 

 for a line of given type is proportional to the square of the 

 atomic number, a relation which has been shown experi- 

 mentally to be of. universal applicability for X-ray spectra. 

 Applying this relation to the group of lines referred to, it can 

 be shown that the frequencies for aluminium corresponding 

 to the high frequency 7 rays of radium C should vary 

 from 1 09 X 10 18 to 12*6 X 10 1S per sec, giving wave-lengths 

 between 2'7 x 10~ 8 and 0*24 X 10~ 8 cm. It will be seen "that 

 these wave-lengths cover the range of the spectrum in 

 which the phenomena ascribed to a J" radiation make their 

 appearance. 



Jf these assumptions are legitimate the " J " radiation. 

 unlike the K radiation, consists not of a group of lines oi 



