﻿Chemistry 
  and 
  Physics. 
  483 
  

  

  temperature 
  for 
  a 
  few 
  seconds 
  only 
  and 
  thus 
  secondary 
  reactions 
  

   were 
  avoided. 
  He 
  found 
  that 
  at 
  600° 
  to 
  800°, 
  neither 
  carbon 
  nor 
  

   an 
  appreciable 
  amount 
  of 
  hydrogen 
  was 
  liberated, 
  but 
  that 
  the 
  

   actual 
  change 
  was 
  a 
  shifting 
  of 
  an 
  atom 
  of 
  hydrogen, 
  forming 
  an 
  

   olefine 
  and 
  either 
  methane 
  or 
  ethane, 
  the 
  latter 
  in 
  the 
  smaller 
  

   quantity. 
  Hexane 
  yields 
  amylene 
  and 
  methane, 
  trimethyletby- 
  

   lene 
  gives 
  methane 
  also 
  but 
  ethylene 
  in 
  addition, 
  a 
  complete 
  

   change 
  of 
  arrangement 
  taking 
  place. 
  Thorpe 
  and 
  Young 
  had 
  

   noticed 
  in 
  1873 
  that 
  paraffin 
  yields 
  no 
  hydrogen 
  on 
  distillation, 
  

   but 
  lower 
  hydrocarbons, 
  of 
  nearly 
  equal 
  molecular 
  mass. 
  In 
  the 
  

   paraffins 
  the 
  union 
  of 
  carbon 
  with 
  carbon 
  is 
  thus 
  more 
  easily 
  dis- 
  

   solved 
  than 
  the 
  union 
  of 
  carbon 
  with 
  hydrogen. 
  But 
  with 
  the 
  

   aromatic 
  hydrocarbons 
  the 
  opposite 
  seems 
  to 
  be 
  the 
  fact, 
  benzene 
  

   for 
  instance 
  giving 
  diphenyl 
  and 
  hydrogen 
  ; 
  although 
  its 
  decom- 
  

   position 
  is 
  more 
  difficult 
  than 
  that 
  of 
  hexane. 
  At 
  900° 
  to 
  1000° 
  

   however 
  the 
  pyrogenic 
  reaction 
  is 
  quite 
  different, 
  coke, 
  tar 
  and 
  

   hydrogen 
  being 
  formed, 
  methane 
  being 
  the 
  only 
  resulting 
  paraffin 
  

   and 
  ethylene 
  the 
  only 
  olefine. 
  Hence 
  ethylene 
  does 
  not 
  unite 
  with 
  

   hydrogen 
  at 
  this 
  temperature. 
  At 
  800° 
  acetylene 
  gives 
  but 
  little 
  

   ethylene 
  with 
  much 
  hydrogen. 
  Methane 
  is 
  quite 
  stable. 
  —Ber. 
  

   Berl. 
  Chem. 
  Ges., 
  xxix, 
  2691-2700, 
  December, 
  1896. 
  g. 
  f. 
  b. 
  

  

  7. 
  On 
  the 
  Explosive 
  Properties 
  of 
  Acetylene. 
  — 
  It 
  has 
  been 
  

   shown 
  by 
  Berthelot 
  and 
  Vieille 
  that 
  when 
  acetylene 
  under 
  

   ordinary 
  pressure 
  is 
  exposed 
  to 
  the 
  action 
  of 
  the 
  electric 
  spark, 
  

   of 
  a 
  red 
  hot 
  wire, 
  or 
  of 
  an 
  explosion 
  of 
  fulminate, 
  the 
  gas 
  is 
  

   decomposed 
  only 
  in 
  the 
  immediate 
  vicinity 
  ; 
  while 
  when 
  the 
  gas 
  

   is 
  under 
  pressure 
  the 
  result 
  is 
  quite 
  different, 
  the 
  gas 
  showing 
  

   the 
  ordinary 
  character 
  of 
  explosive 
  mixtures 
  when 
  the 
  pressure 
  

   exceeds 
  two 
  atmospheres. 
  In 
  this 
  case 
  the 
  explosion 
  rapidly 
  

   spreads 
  through 
  the 
  entire 
  mass 
  of 
  the 
  gas, 
  which 
  decomposes 
  

   into 
  hydrogen 
  and 
  finely 
  divided 
  bulky 
  carbon. 
  If 
  the 
  initial 
  

   pressure 
  be 
  21 
  kilos, 
  per 
  square 
  centimeter, 
  the 
  pressure 
  developed 
  

   is 
  ten 
  times 
  this 
  value, 
  the 
  change 
  being 
  complete 
  in 
  0-018 
  of 
  a 
  

   second. 
  Liquid 
  acetylene 
  decomposes 
  in 
  the 
  same 
  way. 
  Using 
  

   18 
  grams 
  in 
  a 
  bomb 
  of 
  48"96 
  cc 
  capacity, 
  the 
  final 
  pressure 
  was 
  5564 
  

   kilos, 
  per 
  sq. 
  centimeter, 
  almost 
  the 
  equal 
  of 
  gun 
  cotton. 
  Simple 
  

   shock 
  seems 
  incapable 
  of 
  causing 
  acetylene 
  to 
  explode 
  either 
  in 
  

   the 
  gaseous 
  or 
  liquid 
  state. 
  If 
  water 
  be 
  made 
  to 
  act 
  on 
  excess 
  of 
  

   calcium 
  carbide 
  in 
  a 
  closed 
  vessel, 
  the 
  elevation 
  of 
  temperature 
  

   may 
  be 
  sufficient 
  to 
  start 
  the 
  decomposition 
  of 
  the 
  whole 
  of 
  the 
  

   compressed 
  gas. 
  — 
  C. 
  B., 
  cxxiii, 
  523-530, 
  October, 
  1896. 
  g. 
  f. 
  b. 
  

  

  8. 
  On 
  the 
  form 
  of 
  the 
  atoms 
  ; 
  by 
  C. 
  Fourlinnie. 
  Pamphlet, 
  

   8vo. 
  Reims, 
  1896. 
  — 
  In 
  this 
  little 
  work 
  M. 
  Fourlinnie 
  has 
  sought 
  

   to 
  solve 
  the 
  following 
  problem 
  : 
  " 
  Can 
  we 
  explain 
  the 
  properties 
  

   of 
  simple 
  bodies 
  by 
  supposing 
  that 
  their 
  atoms 
  are 
  composed 
  of 
  a 
  

   single 
  and 
  homogeneous 
  substance, 
  but 
  having 
  geometrical 
  forms 
  

   which 
  differ 
  from 
  one 
  simple 
  body 
  to 
  another 
  ?" 
  

  

  Limiting 
  this 
  investigation 
  to 
  the 
  metalloids, 
  the 
  author 
  arrives 
  

   at 
  the 
  conclusion 
  that 
  the 
  metalloids 
  belonging 
  to 
  a 
  single 
  class 
  

   according 
  to 
  Dumas 
  possess 
  atoms 
  of 
  the 
  same 
  form, 
  but 
  of 
  dif- 
  

  

  