﻿382 
  ScientiJiG 
  Intelligence. 
  

  

  SCIENTIFIC 
  INTELLIGENCE. 
  

  

  I. 
  Chemistry 
  and 
  Physics. 
  

  

  1. 
  On 
  the 
  Solidification 
  of 
  Hydrogen. 
  — 
  Toward 
  the 
  end 
  of 
  

   1898, 
  as 
  soon 
  as 
  Dewar 
  had 
  obtained 
  two* 
  or 
  three 
  hundred 
  cubic 
  

   centimeters 
  of 
  liquid 
  hydrogen, 
  he 
  attempted 
  its 
  solidification 
  by- 
  

   boiling 
  it 
  under 
  reduced 
  pressure 
  ; 
  but 
  without 
  result, 
  no 
  solid 
  

   hydrogen 
  being 
  produced, 
  even 
  when 
  the 
  ebullition 
  was 
  effected 
  

   under 
  a 
  pressure 
  as 
  low 
  as 
  ten 
  millimeters. 
  Subsequently 
  he 
  

   observed 
  that 
  a 
  trifling 
  leakage 
  of 
  air, 
  such 
  as 
  it 
  was 
  almost 
  

   impossible 
  to 
  prevent 
  at 
  this 
  low 
  temperature, 
  produced, 
  when 
  

   the 
  pressure 
  was 
  reduced 
  below 
  60™"^ 
  a 
  remarkable 
  effect, 
  causing 
  

   a 
  sudden 
  solidification 
  in 
  the 
  form 
  of 
  a 
  gelatinous 
  froth. 
  At 
  first 
  

   he 
  thought 
  this 
  was 
  a 
  sponge 
  of 
  solid 
  air 
  containing 
  liquid 
  hydro- 
  

   gen. 
  But 
  as 
  it 
  evaporated 
  completely 
  at 
  this 
  low 
  pressure 
  with- 
  

   out 
  leaving 
  more 
  than 
  a 
  trace 
  of 
  solid 
  air, 
  he 
  concluded 
  that 
  it 
  

   must 
  be 
  solid 
  hydrogen. 
  In 
  confirmation 
  of 
  this 
  view, 
  he 
  found 
  

   that 
  on 
  increasing 
  the 
  pressure, 
  and 
  consequently 
  the 
  temperature, 
  

   the 
  solid 
  melted 
  when 
  the 
  pressure 
  attained 
  about 
  55°^™. 
  Using 
  a 
  

   graduated 
  tube 
  attached 
  to 
  a 
  closed 
  balloon 
  of 
  about 
  a 
  liter 
  capacity 
  

   filled 
  with 
  pure 
  hydrogen 
  gas, 
  he 
  found 
  that 
  when 
  this 
  tube 
  

   was 
  immersed 
  in 
  boiling 
  hydrogen, 
  liquid 
  hydrogen 
  accumulated 
  

   in 
  it 
  till 
  the 
  outside 
  pressure 
  reached 
  30 
  or 
  40™"^ 
  and 
  the 
  outside 
  

   liquid 
  became 
  a 
  solid 
  froth. 
  On 
  inverting 
  the 
  apparatus, 
  no 
  flow 
  

   could 
  be 
  observed 
  along 
  the 
  tube 
  ; 
  and 
  in 
  a 
  strong 
  light, 
  the 
  

   material 
  in 
  the 
  lower 
  part 
  of 
  this 
  tube 
  could 
  be 
  seen 
  as 
  a 
  trans- 
  

   parent 
  ice. 
  This 
  solid 
  hydrogen 
  melted 
  at 
  a 
  pressure 
  of 
  55™". 
  

   The 
  temperature 
  of 
  fusion, 
  determined 
  with 
  a 
  hydrogen 
  ther- 
  

   mometer, 
  was 
  found 
  to 
  be 
  about 
  16° 
  absolute, 
  under 
  a 
  pressure 
  of 
  

   35""'", 
  theory 
  indicating 
  16-7°. 
  So 
  that 
  the 
  practical 
  limit 
  of 
  tem- 
  

   perature 
  which 
  can 
  be 
  reached 
  by 
  the 
  evaporation 
  of 
  solid 
  hydro- 
  

   gen 
  is 
  14° 
  or 
  15° 
  absolute. 
  It 
  is 
  to 
  be 
  noted 
  that 
  the 
  critical 
  

   temperature 
  of 
  hydrogen 
  being 
  80° 
  to 
  32° 
  absolute, 
  its 
  fusing 
  

   point 
  is 
  one-half 
  of 
  this, 
  i. 
  e., 
  16°. 
  The 
  frothy 
  appearance 
  of 
  the 
  

   solid, 
  as 
  ordinarily 
  produced, 
  is 
  due 
  to 
  the 
  low 
  density 
  of 
  the 
  

   liquid 
  and 
  its 
  rapid 
  evaporation. 
  These 
  results 
  would 
  seem 
  to 
  

   destroy 
  the 
  hypothesis 
  of 
  the 
  metallic 
  character 
  of 
  hydrogen 
  and 
  

   to 
  require 
  its 
  classification 
  among 
  the 
  non-metallic 
  elements. 
  — 
  

   C. 
  R., 
  cxxix, 
  451-454, 
  September, 
  1899. 
  G. 
  f. 
  b. 
  

  

  2. 
  On 
  Ilydrazoic 
  acid 
  and 
  its 
  salts. 
  — 
  Further 
  researches 
  have 
  

   been 
  made 
  by 
  Cuktius 
  and 
  Rissoit 
  upon 
  hydrazoic 
  acid 
  (HNg) 
  

   and 
  its 
  salts. 
  The 
  acid 
  itself 
  was 
  prepared 
  by 
  distilling 
  with 
  sul- 
  

   phuric 
  acid 
  the 
  lead 
  nitride 
  which 
  is 
  obtained 
  as 
  a 
  by-product 
  in 
  

   the 
  preparation 
  of 
  ammonium 
  nitride. 
  The 
  aqueous 
  solution 
  thus 
  

   obtained 
  is 
  quite 
  permanent 
  even 
  on 
  heating 
  ; 
  but 
  on 
  boiling 
  

   with 
  strong 
  acids 
  it 
  is 
  decomposed 
  with 
  the 
  evolution 
  of 
  gas. 
  

   The 
  ammonium 
  nitride 
  (NII^N^) 
  is 
  the 
  most 
  interesting 
  of 
  the 
  

  

  