﻿160 
  Scientific 
  Intelligence. 
  

  

  more 
  active. 
  The 
  spectrum 
  examined 
  by 
  Demar9ay 
  gave 
  a 
  char- 
  

   acteristic 
  line 
  of 
  wave-length 
  3814-8. 
  In 
  consequence 
  the 
  authors 
  

   propose 
  for 
  the 
  new 
  element 
  the 
  name 
  radium. 
  Like 
  uranium 
  

   and 
  thorium, 
  polonium 
  and 
  radium 
  act 
  2:>hotographically 
  on 
  sensi- 
  

   tive 
  plates 
  and 
  render 
  the 
  surrounding 
  air 
  a 
  conductor 
  of 
  elec- 
  

   tricity 
  ; 
  though 
  they 
  are 
  far 
  more 
  effective. 
  An 
  exposure 
  of 
  half 
  

   a 
  minute 
  gives 
  with 
  the 
  latter 
  an 
  effect 
  equal 
  to 
  that 
  of 
  several 
  

   hours 
  with 
  the 
  former. 
  — 
  (7. 
  i?., 
  cxxvii, 
  175-178, 
  July, 
  1898; 
  1215- 
  

   1217, 
  1218, 
  December, 
  1898. 
  G. 
  f. 
  b. 
  

  

  2. 
  On 
  Liquid 
  Hydrogen. 
  — 
  The 
  Centenary 
  of 
  the 
  Royal 
  Insti- 
  

   tution 
  of 
  Great 
  Britain 
  was 
  fittingly 
  celebrated 
  on 
  the 
  7th 
  of 
  June 
  

   by 
  an 
  admirable 
  lecture, 
  by 
  Professor 
  Dewar, 
  on 
  Liquid 
  Hydro- 
  

   gen 
  as 
  an 
  instrument 
  of 
  research. 
  He 
  had 
  upon 
  the 
  lecture 
  table 
  

   a 
  liter 
  of 
  this 
  substance, 
  preserved 
  in 
  triple 
  vessels 
  containing 
  

   liquid 
  air 
  surrounding 
  the 
  hydrogen. 
  It 
  is 
  transparent 
  and 
  has 
  a 
  

   well-defined 
  meniscus 
  ; 
  and 
  when 
  the 
  cotton 
  plug 
  closing 
  the 
  tube 
  

   is 
  removed, 
  the 
  entering 
  air 
  is 
  at 
  once 
  frozen 
  to 
  a 
  solid 
  and 
  falls 
  

   to 
  the 
  bottom 
  like 
  a 
  precipitate. 
  A 
  small 
  wad 
  of 
  cotton 
  on 
  a 
  

   glass 
  rod 
  dipped 
  into 
  it 
  and 
  lighted 
  gives 
  the 
  well-known 
  hydro- 
  

   gen 
  flame. 
  A 
  small 
  cork 
  ball 
  sinks 
  at 
  once 
  in 
  liquid 
  hydrogen. 
  

   A 
  solid 
  immersed 
  in 
  it 
  for 
  a 
  few 
  seconds 
  becomes 
  so 
  cold 
  that 
  it 
  

   liquefies 
  the 
  surrounding 
  air 
  on 
  withdrawal, 
  which 
  runs 
  off 
  in 
  

   drops; 
  while 
  a 
  tube 
  of 
  liquid 
  air 
  is 
  at 
  once 
  solidified 
  in 
  it. 
  An 
  

   empty 
  bulb 
  placed 
  in 
  the 
  space 
  above 
  the 
  liquid 
  hydrogen 
  is 
  at 
  

   once 
  filled 
  with 
  solid 
  air. 
  Oxygen 
  also 
  becomes 
  solid 
  and 
  when 
  

   lifted 
  out 
  is 
  seen 
  gradually 
  to 
  melt. 
  Though 
  not 
  itself 
  magnetic 
  

   the 
  oxygen 
  liquified 
  from 
  the 
  air 
  on 
  a 
  cotton 
  plug 
  cooled 
  in 
  

   hydrogen 
  is 
  drawn 
  to 
  the 
  magnet. 
  The 
  real 
  temperature 
  of 
  the 
  

   liquid 
  hydrogen 
  he 
  had 
  found 
  to 
  be 
  21° 
  absolute, 
  a 
  hydrogen 
  gas 
  

   thermometer 
  and 
  a 
  german-silver 
  resistance 
  thermometer 
  giving 
  

   the 
  same 
  reading. 
  Very 
  perfect 
  vacua 
  were 
  obtained 
  by 
  cooling 
  

   tubes 
  containing 
  air 
  in 
  liquid 
  hydrogen 
  ; 
  so 
  perfect 
  indeed 
  that 
  

   no 
  electric 
  discharge 
  could 
  pass 
  through 
  them. 
  Comparative 
  

   contraction 
  of 
  a 
  hydrogen 
  thermometer 
  placed 
  in 
  liquid 
  air 
  and 
  

   in 
  liquid 
  hydrogen 
  showed 
  that 
  in 
  the 
  latter 
  was 
  four 
  times 
  

   as 
  great 
  as 
  in 
  the 
  former. 
  To 
  reach 
  the 
  absolute 
  zero 
  even 
  

   approximately 
  two 
  more 
  steps 
  must 
  be 
  made 
  substantially 
  as 
  

   great 
  as 
  the 
  one 
  now 
  made 
  between 
  liquid 
  nitrogen 
  and 
  liquid 
  

   hydrogen. 
  

  

  3. 
  On 
  Ozomolyhdates. 
  — 
  B}^ 
  digesting 
  a 
  molybdate 
  of 
  one 
  of 
  

   the 
  alkali 
  metals 
  with 
  hydrogen 
  peroxide, 
  Muthmaxn 
  and 
  Nagel 
  

   have 
  found 
  it 
  possible 
  to 
  add 
  oxygen 
  to 
  it 
  to 
  the 
  extent 
  of 
  one 
  

   atom 
  of 
  oxygen 
  or 
  less 
  per 
  atom 
  of 
  molybdenum. 
  The 
  com- 
  

   pounds 
  thus 
  formed, 
  however, 
  cannot 
  properly 
  be 
  regarded 
  as 
  salts 
  

   of 
  permolybdic 
  acid, 
  since 
  they 
  lose 
  oxygen 
  readily, 
  reducing 
  

   silver 
  oxide 
  and 
  permanganic 
  acid 
  with 
  evolution 
  of 
  oxygen. 
  

   The 
  apparent 
  addition 
  of 
  an 
  atom 
  of 
  oxygen 
  therefore 
  seems 
  

   really 
  to 
  be 
  a 
  replacement 
  of 
  one 
  atom 
  of 
  oxygen 
  by 
  two 
  linked 
  

   together 
  as 
  in 
  hydrogen 
  peroxide 
  or 
  ozone. 
  Hence 
  the 
  name 
  ozo- 
  

   molyhdates 
  given 
  by 
  the 
  authors 
  to 
  this 
  class 
  of 
  compounds. 
  

  

  