﻿y-Kays 
  of 
  Uranium 
  and 
  Radium. 
  625 
  

  

  several 
  litres 
  oE 
  hot 
  water, 
  and 
  treated 
  ^vith 
  excess 
  o£ 
  a 
  strong- 
  

   solution 
  of 
  ammonium 
  carbonate 
  containing 
  ammonia. 
  Too 
  

   great 
  excess 
  is 
  harmful, 
  as 
  uranyl 
  ammonium 
  carbonate 
  is 
  

   less 
  soluble 
  in 
  ammonium 
  carbonate 
  than 
  in 
  water. 
  Should 
  

   all 
  the 
  uranium 
  carbonate 
  not 
  redissolve 
  the 
  bulk 
  of 
  the 
  

   supernatant 
  liquor 
  is 
  drawn 
  off 
  and 
  a 
  further 
  large 
  quantity 
  

   of 
  hot 
  water 
  added. 
  The 
  liquor 
  is 
  then 
  carelully 
  filtered 
  

   through 
  an 
  extracted 
  filter 
  on 
  the 
  pump 
  and 
  the 
  precipitate 
  

   washed 
  with 
  hot 
  water, 
  redissolved 
  in 
  dilute 
  nitric 
  acid 
  and 
  

   reprecipitated 
  with 
  excess 
  of 
  ammonimn 
  carbonate 
  once 
  or 
  

   twice 
  to 
  ensure 
  complete 
  removal 
  of 
  the 
  uranium. 
  This 
  

   process 
  of 
  separating 
  uranium 
  X 
  is 
  a 
  very 
  efficient 
  one, 
  and 
  

   in 
  some 
  cases 
  the 
  separation 
  was 
  extraordinarily 
  perfect. 
  

   Thus 
  on 
  one 
  occasion 
  to 
  the 
  uranium 
  filtrate 
  from 
  a 
  precipi- 
  

   tate 
  containing 
  the 
  combined 
  quantities 
  of 
  uranium 
  X 
  from 
  

   about 
  40 
  kilograms 
  of 
  uranyl 
  nitrate 
  a 
  little 
  iron 
  chloride 
  

   was 
  added 
  and 
  the 
  original 
  process 
  repeated. 
  The 
  /3-activity 
  

   of 
  this 
  iron 
  precipitate 
  was 
  practically 
  inappreciable. 
  When 
  

   it 
  is 
  considered 
  that 
  the 
  actual 
  weight 
  of 
  uranium 
  X 
  in 
  

   equilibrium 
  with 
  50 
  kilograms 
  of 
  uranyl 
  nitrate 
  is 
  below 
  

   '0005 
  mg., 
  the 
  removal 
  from 
  the 
  uranium 
  solution 
  of 
  the 
  

   whole 
  of 
  this, 
  all 
  except 
  perhaps 
  50000 
  P^^'^ 
  ^^ 
  most, 
  in 
  

   a 
  single 
  precipitation 
  is 
  a 
  very 
  remarkable 
  operation. 
  This 
  

   is 
  an 
  exceptional 
  case, 
  but 
  usually 
  the 
  amount 
  of 
  uranium 
  X 
  

   in 
  the 
  filtrate 
  was 
  relatively 
  small. 
  In 
  the 
  first 
  separation 
  the 
  

   combined 
  uranium-X-containing 
  precipitates 
  weighed 
  about 
  

   4*8 
  grams, 
  in 
  the 
  second 
  it 
  was 
  much 
  less, 
  and 
  in 
  the 
  third 
  it 
  

   was 
  only 
  0'65 
  gram. 
  These 
  precipitates, 
  which 
  naturally 
  

   have 
  considerable 
  chemical 
  interest, 
  have 
  not 
  yet 
  been 
  ex- 
  

   haustively 
  examined. 
  It 
  was 
  not 
  difficult 
  to 
  recognize 
  two 
  

   groups 
  of 
  substances 
  (in 
  about 
  equal 
  quantity 
  in 
  the 
  first 
  batch), 
  

   the 
  one 
  consisting 
  of 
  common 
  earths, 
  largely 
  alumina, 
  and 
  

   the 
  other 
  consisting 
  of 
  a 
  pale 
  yellow 
  body 
  more 
  closely 
  allied 
  

   to 
  uranium, 
  and 
  possibly 
  a 
  member 
  of 
  the 
  tungsten 
  family. 
  

   In 
  the 
  last 
  separation 
  the 
  precipitate 
  consisted 
  mainly 
  of 
  the 
  

   latter 
  substance. 
  The 
  separation 
  of 
  the 
  two 
  groups 
  was 
  

   simply 
  effected 
  by 
  solution 
  of 
  the 
  precipitate 
  in 
  nitric 
  acid, 
  

   and 
  by 
  the 
  cautious 
  addition 
  of 
  ammonia, 
  below 
  the 
  quantity 
  

   required 
  for 
  neutralization, 
  until 
  a 
  yellow 
  colour 
  made 
  its 
  

   appearance. 
  On 
  setting 
  aside 
  for 
  a 
  few 
  hours, 
  the 
  yellow 
  

   body 
  precipitated 
  out, 
  containing 
  nearly 
  all 
  the 
  uranium 
  X, 
  

   leaving 
  the 
  alumina 
  &c. 
  in 
  the 
  still 
  acid 
  solution. 
  In 
  this 
  

   way 
  further 
  concentration 
  of 
  the 
  uranium 
  X 
  could 
  be 
  effected, 
  

   but 
  not 
  much 
  was 
  gained 
  by 
  it. 
  It 
  has 
  recently 
  been 
  

   noticed 
  that 
  this 
  yellow 
  compound 
  is, 
  like 
  uranium 
  carbonate, 
  

   soluble 
  in 
  an 
  excess 
  of 
  ammonium 
  carbonate, 
  but 
  to 
  a 
  much 
  

  

  