﻿Disintegration 
  of 
  Uranium 
  X. 
  529 
  

  

  o£ 
  neither 
  of 
  these 
  substances 
  has 
  yet 
  been 
  confirmed. 
  The 
  

   theoretical 
  considerations 
  put 
  forward 
  almost 
  simultaneously 
  

   regarding 
  the 
  evolution 
  of 
  the 
  radio-elements 
  through 
  the 
  

   periodic 
  law 
  by 
  Hussell 
  *, 
  Fajans 
  t? 
  and 
  Soddy 
  % 
  led 
  to 
  the 
  

   belief 
  that 
  one 
  other 
  substance 
  should 
  exist 
  before 
  ionium, 
  

   and 
  in 
  a 
  short 
  paper 
  published 
  by 
  Fajans 
  and 
  Gohring 
  § 
  the 
  

   discovery 
  of 
  such 
  a 
  body 
  is 
  announced. 
  It 
  is 
  called 
  by 
  the 
  

   authors 
  " 
  uranium 
  X 
  c2 
  " 
  ; 
  its 
  peiiod 
  of 
  half-value 
  is 
  stated 
  as 
  

   l'l 
  minutes, 
  and 
  the 
  only 
  method 
  of 
  separation 
  given 
  is 
  that 
  

   of 
  placing 
  a 
  lead 
  plate 
  in 
  a 
  weakly 
  acid 
  solution 
  ot 
  uranium 
  X. 
  

   On 
  removing 
  tbe 
  plate 
  and 
  measuring 
  its 
  activity 
  a 
  rapid 
  

   initial 
  fall 
  was 
  observed. 
  By 
  a 
  method 
  not 
  stated 
  the 
  rise 
  

   of 
  ft 
  activity 
  from 
  a 
  uranium 
  X 
  preparation 
  was 
  also 
  observed. 
  

   The 
  name 
  uranium 
  X 
  x 
  was 
  given 
  to 
  the 
  substance 
  with 
  the 
  

   period 
  of 
  average 
  life 
  of 
  35*5 
  days. 
  The 
  object 
  of 
  the 
  work 
  

   that 
  will 
  be 
  described 
  in 
  this 
  paper 
  was 
  to 
  attempt 
  to 
  confirm 
  

   the 
  existence 
  of 
  this 
  short-lived 
  radio-element, 
  and 
  this 
  has 
  

   been 
  successfully 
  done. 
  The 
  term 
  uranium 
  X 
  will 
  be 
  used 
  

   to 
  denote 
  uranium 
  X 
  x 
  in 
  equilibrium 
  with 
  uranium 
  X 
  2 
  . 
  

  

  The 
  deposition 
  of 
  uranium 
  X 
  on 
  metallic 
  plates 
  was 
  studied, 
  

   -and 
  it 
  was 
  found 
  that 
  when 
  a 
  plate 
  of 
  gold 
  or 
  platinum 
  was 
  

   placed 
  in 
  a 
  weakly 
  acid 
  solution 
  of 
  uranium 
  X 
  no 
  detectable 
  

   quantity 
  of 
  activity 
  was 
  obtained 
  on 
  the 
  plate. 
  Measurable 
  

   quantities 
  of 
  uranium 
  X 
  were, 
  however, 
  obtained 
  by 
  placing 
  

   zinc 
  and 
  magnesium 
  plates 
  in 
  such 
  a 
  solution. 
  When 
  the 
  

   activity 
  of 
  such 
  plates 
  was 
  measured 
  no 
  initial 
  rapid 
  decay 
  

   was 
  observed. 
  If, 
  however, 
  a 
  plate 
  of 
  lead 
  was 
  used 
  a 
  rapid 
  

   initial 
  decay 
  was 
  obtained. 
  The 
  method 
  employed 
  was 
  to 
  

   cut 
  a 
  flat 
  clean 
  plate 
  of 
  lead 
  just 
  smaller 
  than 
  the 
  base 
  of 
  

   a 
  flat-bottomed 
  crystallizing 
  dish 
  in 
  which 
  the 
  lead 
  was 
  

   placed. 
  The 
  solution 
  of 
  uranium 
  X 
  was 
  made 
  just 
  acid 
  

   with 
  nitric 
  acid, 
  and, 
  occupying 
  not 
  more 
  than 
  5 
  c.c, 
  w 
  T 
  as 
  

   then 
  poured 
  over 
  the 
  plate, 
  and 
  the 
  liquid 
  kept 
  agitated 
  for 
  

   five 
  minutes. 
  The 
  lead 
  plate 
  was 
  then 
  withdrawn, 
  drained, 
  

   and 
  washed 
  in 
  alcohol 
  which 
  was 
  finally 
  removed 
  by 
  burning. 
  

   When 
  cool 
  the 
  plate 
  was 
  immediately 
  taken 
  to 
  an 
  electro- 
  

   scope 
  and 
  the 
  hard 
  ft 
  activity 
  measured, 
  the 
  first 
  measure- 
  

   ment 
  being 
  usually 
  made 
  from 
  one 
  and 
  a 
  half 
  to 
  two 
  minutes 
  

   after 
  the 
  instant 
  of 
  withdrawal 
  of 
  the 
  lead 
  plate 
  from 
  the 
  

   uranium 
  X 
  solution. 
  It 
  was 
  then 
  found 
  that 
  after 
  six 
  or 
  

  

  * 
  Russell, 
  Cheni. 
  News, 
  cvii. 
  p. 
  49 
  (1913). 
  

  

  t 
  Fajans, 
  Physikal. 
  Zeitsch. 
  xiv. 
  p. 
  131 
  (1913) 
  : 
  Ber. 
  xivi. 
  p. 
  422 
  

   (1913). 
  

  

  X 
  Soddv, 
  Chem. 
  News, 
  cvii. 
  p. 
  97 
  (1913) 
  ; 
  JaJirb. 
  Radiodktiv. 
  

   EhktroniL 
  x. 
  p. 
  188 
  (1913). 
  

  

  ' 
  § 
  Fajans 
  & 
  Gohring, 
  Die 
  Xaturicissenschaften, 
  4th 
  April, 
  1913, 
  

   Heft 
  xiv. 
  p. 
  339. 
  

  

  