﻿Chemistry 
  and 
  Physics. 
  421 
  

  

  orbit 
  is 
  definitely 
  known, 
  and 
  it 
  may 
  or 
  may 
  not 
  be 
  found 
  to 
  

   be 
  nearer 
  the 
  mean- 
  plane 
  than 
  at 
  present.* 
  

  

  The 
  reason 
  for 
  the 
  relation 
  of 
  Jupiter's 
  plane 
  to 
  the 
  minor 
  

   planet 
  planes 
  is 
  evident. 
  The 
  secular 
  perturbation 
  of 
  the 
  orbit 
  

   of 
  a 
  minor 
  planet 
  by 
  Jupiter 
  is 
  such 
  that 
  the 
  inclination 
  of 
  the 
  

   orbit 
  plane 
  is 
  not 
  greatly 
  changed, 
  but 
  the 
  node 
  has 
  a 
  constant 
  

   motion. 
  The 
  pole 
  of 
  the 
  planet's 
  plane 
  therefore 
  is 
  constantly 
  

   describing 
  a 
  curve, 
  not 
  widely 
  departing 
  from 
  a 
  circle, 
  around 
  

   the 
  pole 
  of 
  Jupiter's 
  plane. 
  This 
  motion 
  is 
  greater 
  for 
  some 
  

   minor 
  planets 
  than 
  for 
  others. 
  Hence 
  whatever 
  be 
  the 
  distri- 
  

   bution 
  of 
  the 
  poles 
  at 
  one 
  epoch, 
  the 
  tendency 
  of 
  the 
  secular 
  

   perturbation 
  by 
  Jupiter 
  is 
  to 
  finally 
  distribute 
  the 
  minor-planet 
  

   poles 
  symmetrically 
  around 
  the 
  pole 
  of 
  Jupiter's 
  plane. 
  

  

  SCIENTIFIC 
  INTELLIGENCE. 
  

  

  I. 
  Chemistry 
  and 
  Physics.- 
  

  

  1. 
  On 
  the 
  Presence 
  of 
  Argon 
  and 
  of 
  Helium 
  in 
  Uraninite. 
  — 
  

   At 
  a 
  meeting 
  of 
  the 
  Chemical 
  Society 
  of 
  London 
  on 
  March 
  27th, 
  

   Ramsay 
  announced 
  that 
  he 
  had 
  discovered 
  both 
  argon 
  and 
  

   helium 
  in 
  the 
  mineral 
  cleveite, 
  a 
  variety 
  of 
  uraninite. 
  His 
  atten- 
  

   tion 
  was 
  first 
  called 
  to 
  this 
  mineral 
  by 
  Miers 
  of 
  the 
  British 
  

   Museum, 
  since 
  Hillebrand 
  had 
  shownf 
  that 
  when 
  treated 
  with 
  

   dilute 
  sulphuric 
  acid 
  and 
  warmed, 
  the 
  uraninite 
  gave 
  off 
  two 
  per 
  

   cent 
  or 
  more 
  of 
  a 
  gas 
  which 
  from 
  the 
  tests 
  he 
  applied 
  to 
  it 
  

   appeared 
  to 
  be 
  nitrogen. 
  On 
  sparking 
  with 
  oxygen 
  however, 
  

   in 
  presence 
  of 
  soda, 
  Ramsay 
  found 
  that 
  the 
  gas 
  which 
  he 
  obtained 
  

   from 
  this 
  mineral 
  contained 
  only 
  a 
  trace 
  of 
  nitrogen 
  intro- 
  

   duced 
  probably 
  during 
  its 
  extraction. 
  In 
  a 
  Pliicker 
  tube 
  its 
  

   spectrum 
  showed 
  all 
  the 
  more 
  prominent 
  argon 
  lines 
  and 
  in 
  addi- 
  

   tion 
  a 
  brilliant 
  line 
  close 
  to, 
  but 
  not 
  coincident 
  with, 
  the 
  D 
  lines 
  

   of 
  sodium. 
  Besides 
  these 
  there 
  were 
  a 
  number 
  of 
  other 
  lines, 
  one 
  

   in 
  the 
  green 
  being 
  especially 
  prominent. 
  Moreover 
  argon 
  

   obtained 
  from 
  the 
  atmosphere 
  shows 
  three 
  lines 
  in 
  the 
  violet 
  

   which 
  are 
  not 
  to 
  be 
  seen 
  apparently 
  in 
  the 
  gas 
  from 
  cleveite. 
  

   Hence 
  the 
  author 
  suggests 
  that 
  possibly 
  atmospheric 
  argon 
  con- 
  

   tains 
  some 
  other 
  gas 
  in 
  admixture, 
  not 
  yet 
  separated, 
  which 
  may 
  

   possibly 
  account 
  for 
  the 
  anomalous 
  position 
  of 
  argon 
  in 
  its 
  

   numerical 
  relations 
  with 
  other 
  elements. 
  Further 
  results 
  are 
  

   promised, 
  especially 
  in 
  relation 
  to 
  the 
  density 
  of 
  the 
  mixture, 
  a 
  

   point 
  of 
  very 
  great 
  interest. 
  

  

  * 
  If 
  we 
  consider 
  the 
  planes 
  of 
  the 
  orbits 
  of 
  the 
  eight 
  principal 
  planets, 
  Jupiter's 
  

   plane 
  is 
  not 
  the 
  nearest 
  to 
  the 
  mean-plane 
  of 
  the 
  system. 
  But 
  by 
  omission 
  of 
  

   the 
  plane 
  of 
  Mercury, 
  the 
  mean-plane 
  of 
  the 
  seven 
  other 
  principal 
  planets 
  is 
  

   a 
  little 
  nearer 
  to 
  Jupiter's 
  plane 
  than 
  it 
  is 
  to 
  any 
  other 
  planetary 
  plane. 
  

  

  f 
  This 
  Journal, 
  III, 
  xl, 
  384, 
  Xovember, 
  1890. 
  

  

  