Artificial Disintegration of Light Elements. 825 



definite idea o£ the distance of the satellites from the central 

 nucleus, or of its orbital velocity. 



It is of interest in this connexion to note that H atoms do 

 not appear to be released from aluminium by a particles of 

 range less than 5 cm. The number liberated increases 

 rapidly as the speed of the a particle is increased. This 

 shows that the " disruption " potential of the nucleus by an a 

 particle, i. e. the potential difference required to communicate 

 the same energy to an electron as is possessed by the a particle, 

 is of the order of 6 million volts for aluminium ; but the ex- 

 perimental effects are so small that it is difficult to estimate 

 this disruption potential with any accuracy. It is of interest 

 to note that the corresponding potential to liberate an electron 

 from the K or inner ring of electrons is about 2200 volts for 

 aluminium. This question will be discussed later in more 

 detail when the critical velocity for disruption is determined 

 for the other elements. 



If our view is correct that the H nuclei are satellites of 

 the central nucleus, the mass of the H satellite should not be 

 very different from that of the free H nucleus. If it be 

 supposed that the nitrogen nucleus is derived from that of 

 carbon by the addition of two H satellites and one electron, 

 it is to be anticipated that the mass of the nitrogen atom 

 should be 14*016 nearly, assuming = 12-00, H = 1*008 in 

 terms of = 16. 



By accurate experiment with positive rays by Aston's 

 method, it should be possible to decide whether the atomic 

 mass of nitrogen is nearer this calculated value than the 

 whole number 14. Similar considerations should be appli- 

 cable to the other elements from which H atoms can be 

 liberated. 



We are much indebted to Mr. B. S. Bieler and Mr. C. D. 

 Ellis for their help in counting scintillation s, and to 

 Mr. Crowe for preparing the radioactive sources. 



Cavendish Laboratory, 

 Aug. 11, 1921. 



Phil. Mag. S. 6. Vol. 42. No. 251. JS\n<. 1921, 



