﻿150 
  Scientific 
  Intelligence. 
  

  

  of 
  felt 
  the 
  lower 
  half; 
  the 
  propane 
  condensing 
  above 
  and 
  collect- 
  

   ing 
  below. 
  By 
  removing 
  the 
  felt 
  the 
  liquid 
  boiled, 
  at 
  first 
  

   irregularly 
  ; 
  but 
  it 
  finally 
  became 
  steady 
  and 
  the 
  corrected 
  tem- 
  

   perature-reading 
  was 
  found 
  to 
  be 
  — 
  31° 
  at 
  '760 
  mm 
  . 
  The 
  vapor 
  

   pressures 
  at 
  different 
  temperatures 
  from 
  —33° 
  to 
  +12*5° 
  were 
  

   determined 
  by 
  placing 
  the 
  liquid 
  propane 
  in 
  one 
  leg 
  of 
  a 
  U-tube 
  

   and 
  air 
  in 
  the 
  other; 
  the 
  two 
  being 
  separated 
  by 
  mercury 
  and 
  

   the 
  pressure 
  estimated 
  from 
  the 
  compression 
  of 
  the 
  air. 
  From 
  

   12*5° 
  to 
  102° 
  the 
  pressure 
  was 
  measured 
  in 
  a 
  Cailletet 
  apparatus. 
  

   It 
  was 
  found 
  that 
  at 
  —33°, 
  the 
  pressure 
  was 
  1*8 
  atmospheres; 
  

   at 
  -19°, 
  2-7; 
  at— 
  15°, 
  3-1; 
  at 
  —11°, 
  36; 
  at 
  —5°, 
  4*1; 
  at 
  -2°, 
  

   4-8; 
  at 
  +1°, 
  5-1; 
  at 
  5-5°, 
  5-9; 
  at 
  12*5°, 
  M; 
  at 
  22°, 
  9; 
  at 
  53°, 
  

   IV; 
  at 
  85°, 
  35; 
  and 
  at 
  102°, 
  48-5 
  atmospheres. 
  The 
  critical 
  tem- 
  

   perature 
  of 
  propane 
  is 
  102° 
  and 
  the 
  corresponding 
  critical 
  pres- 
  

   sure 
  48*5 
  atmospheres. 
  Hence, 
  propane 
  may 
  be 
  sealed 
  safely 
  in 
  

   glass 
  tubes 
  when 
  surrounded 
  with 
  solid 
  carbon 
  dioxide, 
  and 
  thus 
  

   preserved. 
  It 
  is 
  colorless 
  and 
  much 
  more 
  viscous 
  than 
  liquid 
  

   carbon 
  dioxide. 
  Its 
  density 
  at 
  0° 
  is 
  0*536, 
  at 
  6*2°, 
  0*524, 
  at 
  11-5°, 
  

   0*520, 
  and 
  at 
  15'9°, 
  0*515. 
  The 
  examination 
  of 
  liquid 
  ethane 
  was 
  

   more 
  difficult 
  owing 
  to 
  its 
  lower 
  boiling 
  point. 
  The 
  gas 
  was 
  pre- 
  

   pared 
  from 
  ethyl 
  iodide 
  and 
  the 
  zinc-copper 
  couple 
  of 
  Gladstone 
  

   and 
  Tribe. 
  Although 
  a 
  mixture 
  of 
  solid 
  carbon 
  dioxide 
  and 
  ether 
  

   was 
  found 
  insufficient 
  to 
  liquefy 
  ethane, 
  liquid 
  ethylene 
  afforded 
  

   the 
  necessary 
  low 
  temperature 
  and 
  the 
  ethane 
  readily 
  condensed 
  

   to 
  a 
  liquid 
  in 
  the 
  boiling 
  point 
  apparatus, 
  where 
  its 
  temperature 
  

   was 
  determined 
  by 
  means 
  of 
  a 
  thermo 
  element. 
  When 
  in 
  regular 
  

   ebullition, 
  its 
  boiling 
  point 
  was 
  found 
  to 
  be 
  - 
  89*5° 
  at 
  735 
  mm 
  

   pressure. 
  The 
  determination 
  of 
  the 
  pressure 
  at 
  different 
  tem- 
  

   peratures 
  was 
  effected 
  in 
  a 
  modified 
  Cailletet 
  apparatus. 
  The 
  

   critical 
  temperature 
  was 
  found 
  to 
  be 
  34*5° 
  and 
  the 
  critical 
  pres- 
  

   sure 
  50 
  atmospheres. 
  The 
  meniscus 
  became 
  hazy 
  at 
  32° 
  and 
  dis- 
  

   appeared 
  completely 
  only 
  at 
  40°. 
  At 
  31°, 
  the 
  pressure 
  is 
  11 
  

   atmospheres 
  ; 
  at 
  —20°, 
  145 
  ; 
  at 
  —1 
  1°, 
  18*3 
  ; 
  at 
  0°, 
  23*3 
  ; 
  at 
  -flo 
  , 
  

   32*3 
  ; 
  and 
  at 
  4-34*5°, 
  50. 
  The 
  density 
  of 
  liquid 
  ethane 
  at 
  0° 
  is 
  

   0*446, 
  and 
  at 
  10*5°, 
  0396. 
  — 
  Liebig's 
  Annalen, 
  cclxxxii, 
  229, 
  

   October, 
  1894. 
  g. 
  f. 
  b. 
  

  

  5. 
  On 
  the 
  Effect 
  of 
  Low 
  Temperatures 
  on 
  Chloroform. 
  — 
  An 
  

   interesting 
  example 
  of 
  the 
  anomalous 
  behavior 
  of 
  substances 
  at 
  

   very 
  low 
  temperatures 
  has 
  been 
  observed 
  by 
  Raoul 
  Pictet 
  in 
  

   the 
  case 
  of 
  chloroform. 
  In 
  the 
  preparation 
  of 
  this 
  substance 
  in 
  

   the 
  pure 
  state 
  by 
  crystallization 
  at 
  —69° 
  he 
  made 
  use 
  of 
  two 
  

   copper 
  refrigerators, 
  of 
  capacities 
  of 
  2^ 
  and 
  32 
  liters 
  respectively. 
  

   In 
  the 
  first 
  series 
  of 
  experiments, 
  the 
  former 
  only 
  was 
  used. 
  

   About 
  2 
  kilograms 
  of 
  commercial 
  chloroform 
  in 
  a 
  glass 
  cylinder 
  

   was 
  placed 
  in 
  the 
  refrigerator 
  and 
  cooled 
  to 
  —120°, 
  as 
  indicated 
  

   by 
  an 
  ether 
  thermometer. 
  The 
  chloroform 
  appeared 
  turbid 
  at 
  

   — 
  40° 
  or 
  —50°, 
  and 
  was 
  filtered 
  and 
  again 
  cooled. 
  At 
  — 
  68*5°, 
  

   the 
  cooling 
  ceased 
  and 
  very 
  transparent 
  crystals 
  of 
  chloroform 
  

   appeared 
  on 
  the 
  wails 
  of 
  the 
  tube. 
  Owing 
  to 
  the 
  ansesthetic 
  

   advantages 
  of 
  the 
  pure 
  chloroform 
  thus 
  obtained, 
  attempts 
  were- 
  

  

  