﻿Chemistry 
  and 
  Physics. 
  63 
  

  

  only 
  in 
  an 
  impure 
  state, 
  had 
  a 
  density 
  of 
  32-5 
  and 
  was 
  called 
  

   xenon. 
  It 
  could 
  not 
  be 
  detected 
  in 
  the 
  15 
  liters 
  of 
  argon, 
  but 
  

   only 
  in 
  the 
  large 
  quantities 
  of 
  liquid 
  air 
  used. 
  It 
  has 
  several 
  lines 
  

   in 
  its 
  spectrum 
  but 
  none 
  are 
  brilliant. 
  — 
  Ber. 
  Berl. 
  Ghem. 
  Ges., 
  

   xxxi, 
  3111-3121, 
  Dec, 
  1898. 
  G. 
  f. 
  b. 
  

  

  3. 
  Gn 
  the 
  Preparation 
  of 
  Calcium 
  and 
  Calcium 
  hydride. 
  — 
  By 
  

   the 
  electrolysis 
  of 
  anhydrous 
  calcium 
  chloride 
  in 
  a 
  graphite 
  cruci- 
  

   ble 
  containing 
  a 
  porous 
  cell 
  vox 
  Lengtel 
  has 
  obtained 
  metallic 
  

   calcium. 
  The 
  positive 
  electrode 
  was 
  placed 
  in 
  the 
  crucible 
  and 
  

   the 
  negative 
  in 
  the 
  porous 
  cup, 
  a 
  current 
  of 
  10-18 
  amperes 
  under 
  

   a 
  pressure 
  of 
  70-110 
  volts 
  being 
  employed. 
  On 
  placing 
  the 
  regu- 
  

   lus 
  obtained 
  in 
  anhydrous 
  ether 
  a 
  product 
  is 
  obtained 
  containing 
  

   99 
  - 
  2 
  per 
  cent 
  of 
  calcium. 
  The 
  metal 
  has 
  a 
  density 
  of 
  1*5540 
  at 
  

   18°, 
  resembles 
  in 
  color 
  a 
  gold 
  alloy 
  rich 
  in 
  silver, 
  is 
  not 
  affected 
  

   by 
  cold 
  dry 
  air, 
  but 
  burns 
  brilliantly 
  at 
  a 
  red 
  heat. 
  It 
  unites 
  at 
  

   ordinary 
  temperatures 
  with 
  hydrogen 
  to 
  form 
  the 
  hydride 
  CaH 
  2 
  , 
  

   the 
  action 
  being 
  very 
  energetic 
  at 
  a 
  red 
  heat. 
  This 
  hydride 
  is 
  a 
  

   grayish 
  earthy 
  substance 
  which 
  decomposes 
  water 
  even 
  more 
  read- 
  

   ily 
  than 
  the 
  metal, 
  the 
  hydrogen 
  often 
  inflaming, 
  and 
  burns 
  bril- 
  

   liantly 
  in 
  oxygen 
  at 
  a 
  red 
  heat. 
  — 
  Ghem. 
  Centralbl., 
  ii, 
  262, 
  1898. 
  

   J. 
  Ghem. 
  Soc, 
  lxxvi, 
  ii, 
  218, 
  April, 
  1899. 
  G. 
  f. 
  b. 
  

  

  4. 
  Gn 
  Non-explosive 
  Decomposition. 
  — 
  It 
  has 
  been 
  pointed 
  out 
  

   by 
  Hoitsema 
  that 
  rapid 
  and 
  slow 
  decompositions 
  in 
  some 
  cases 
  

   yield 
  products 
  which 
  are 
  identical, 
  while 
  in 
  others 
  the 
  reverse 
  

   obtains. 
  Since 
  gun-cotton 
  belongs 
  to 
  the 
  latter 
  class 
  of 
  sub- 
  

   stances, 
  no 
  explosion-velocity 
  experiments 
  are 
  possible. 
  At 
  about 
  

   150° 
  it 
  can 
  be 
  slowly 
  decomposed 
  without 
  explosion, 
  evolving 
  

   gases 
  containing 
  a 
  little 
  ]ST 
  2 
  4 
  and 
  leaving 
  a 
  non-explosive 
  peat- 
  

   like 
  mass 
  containing 
  about 
  7 
  per 
  cent 
  of 
  nitrogen. 
  Higher 
  nitro- 
  

   gen 
  oxides 
  do 
  not 
  appear 
  to 
  result 
  from 
  secondary 
  reactions, 
  since 
  

   it 
  is 
  easy 
  to 
  prove 
  by 
  special 
  apparatus 
  that 
  they 
  precede 
  the 
  

   formation 
  of 
  nitric 
  oxide. 
  It 
  would 
  seem, 
  therefore, 
  that 
  these 
  

   higher 
  oxides 
  are 
  due 
  to 
  impurity, 
  or 
  are 
  produced 
  only 
  in 
  the 
  

   initial 
  stages 
  of 
  the 
  reaction. 
  Ordinarily 
  the 
  stability 
  of 
  a 
  gun 
  

   cotton 
  is 
  determined 
  by 
  observing 
  the 
  time 
  elapsing 
  before 
  nitric 
  

   fumes 
  are 
  evolved 
  at 
  a 
  fixed 
  temperature. 
  In 
  the 
  author's 
  appa- 
  

   ratus 
  the 
  explosive 
  may 
  be 
  maintained 
  at 
  any 
  desired 
  tempera- 
  

   ture 
  for 
  any 
  length 
  of 
  time. 
  Hence 
  he 
  thinks 
  it 
  better 
  to 
  ascer- 
  

   tain 
  the 
  highest 
  temperature 
  at 
  which 
  the 
  sample 
  may 
  be 
  kept 
  

   for 
  a 
  quarter 
  of 
  an 
  hour 
  or 
  so 
  without 
  emitting 
  nitrous 
  fumes. 
  — 
  

   Zeitschr. 
  physikal. 
  Chem., 
  xxvii, 
  567-578, 
  Dec, 
  1898. 
  g. 
  f. 
  b. 
  

  

  5. 
  Gn 
  Crystalline 
  Liquids. 
  — 
  It 
  is 
  well 
  known 
  that 
  two 
  views 
  

   are 
  held 
  on 
  the 
  subject 
  of 
  crystalline 
  liquids; 
  the 
  one 
  by 
  Lehmann 
  

   who 
  regards 
  them 
  as 
  crystals 
  of 
  remarkably 
  small 
  viscosity, 
  the 
  

   other 
  by 
  Quincke 
  who 
  maintains 
  that 
  they 
  consist 
  of 
  a 
  multitude 
  

   of 
  minute 
  solid 
  crystallites 
  each 
  enclosed 
  in 
  a 
  thin 
  liquid 
  film. 
  

   Schenck 
  has 
  pointed 
  out 
  that 
  if 
  the 
  latter 
  supposition 
  be 
  true, 
  

   the 
  liquid 
  crystals 
  not 
  being 
  homogeneous, 
  then 
  different 
  transi- 
  

   tion 
  temperatures 
  ought 
  to 
  be 
  found 
  for 
  different 
  preparations 
  

   and 
  for 
  the 
  products 
  crystallized 
  from 
  different 
  solvents. 
  To 
  test 
  

  

  