﻿Chemistry 
  and 
  Physics. 
  229 
  

  

  reaches 
  to 
  the 
  bottom. 
  At 
  top 
  these 
  tubes 
  are 
  bent 
  at 
  right 
  

   angles, 
  in 
  opposite 
  directions. 
  In 
  making 
  a 
  determination, 
  the 
  

   salt 
  constituting 
  the 
  bath, 
  contained 
  in 
  a 
  large 
  platinum 
  crucible, 
  

   is 
  fused 
  and 
  the 
  bulb 
  of 
  the 
  air 
  thermometer, 
  with 
  the 
  attached 
  

   substance-tube, 
  is 
  immersed 
  therein 
  ; 
  connection 
  being 
  made 
  

   between 
  one 
  of 
  the 
  capillary 
  tubes 
  and 
  a 
  carbon 
  dioxide 
  appa- 
  

   ratus 
  and 
  between 
  the 
  other 
  and 
  the 
  gas 
  measuring 
  burette. 
  To 
  

   fix 
  the 
  point 
  of 
  fusion, 
  a 
  fine 
  platinum 
  wire 
  is 
  previously 
  immersed 
  

   in 
  the 
  fused 
  substance, 
  this 
  wire 
  being 
  attached 
  to 
  a 
  weight 
  by 
  

   means 
  of 
  a 
  cord 
  passing 
  over 
  a 
  pulley. 
  When 
  now 
  the 
  substance 
  

   is 
  again 
  fused 
  by 
  means 
  of 
  the 
  bath, 
  the 
  wire 
  is 
  released 
  and 
  the 
  

   weight 
  falls 
  and 
  strikes 
  a 
  bell. 
  The 
  current 
  of 
  carbon 
  dioxide 
  is 
  

   then 
  started 
  and 
  by 
  its 
  means 
  the 
  air 
  in 
  the 
  air-thermometer 
  is 
  

   driven 
  into 
  the 
  measuring 
  burette. 
  Knowing 
  the 
  capacity 
  of 
  the 
  

   thermometer, 
  and 
  the 
  volume 
  of 
  air 
  expelled, 
  the 
  temperature 
  can 
  

   be 
  calculated. 
  By 
  the 
  new 
  method 
  the 
  author 
  has 
  determined 
  the 
  

   fusing 
  points 
  of 
  KC1 
  as 
  800*0°, 
  of 
  KBr 
  as 
  722*0°, 
  of 
  KI 
  as 
  684-7° 
  ; 
  

   and 
  of 
  NaCl 
  as 
  815-4°, 
  of 
  NaBr 
  as 
  757*7° 
  and 
  of 
  Nal 
  as 
  661*4°; 
  

   showing 
  that 
  a 
  rise 
  in 
  the 
  atomic 
  mass 
  of 
  the 
  halogen 
  causes 
  a 
  

   fall 
  in 
  the 
  melting 
  point. 
  Moreover, 
  he 
  observed 
  for 
  Rbl 
  the 
  

   value 
  641-5° 
  and 
  for 
  Csl, 
  621*0°; 
  that 
  for 
  KI 
  being 
  684*7°. 
  For 
  

   CaCl 
  2 
  the 
  fusing 
  point 
  obtained 
  was 
  806*4°, 
  for 
  SrCl 
  2 
  832*0° 
  and 
  

   for 
  BaCl 
  2 
  , 
  921*8°. 
  While 
  therefore 
  the 
  melting 
  point 
  falls 
  as 
  the 
  

   atomic 
  mass 
  rises, 
  in 
  the 
  case 
  of 
  the 
  alkali 
  iodides, 
  the 
  reverse 
  is 
  

   the 
  case 
  with 
  the 
  chlorides 
  of 
  the 
  alkali-earths. 
  In 
  either 
  case 
  

   however, 
  the 
  salt 
  of 
  intermediate 
  molecular 
  mass 
  shows 
  an 
  inter- 
  

   mediate 
  fusing 
  point. 
  — 
  Per. 
  Perl. 
  Chem. 
  Ges. 
  9 
  xxvii, 
  3129, 
  

   November, 
  1894. 
  g. 
  f. 
  b. 
  

  

  2. 
  On 
  the 
  Preparation 
  of 
  anhydrous 
  Hydrogen 
  peroxide. 
  — 
  It 
  

   has 
  been 
  shown 
  by 
  Wolffenstein 
  that 
  hydrogen 
  peroxide, 
  

   hitherto 
  considered 
  as 
  very 
  unstable, 
  is 
  capable 
  of 
  concentration 
  

   and 
  even 
  of 
  actual 
  distillation 
  under 
  diminished 
  pressure, 
  with 
  

   but 
  little 
  loss 
  from 
  decomposition. 
  Ascertaining 
  that 
  the 
  loss 
  on 
  

   concentration 
  either 
  in 
  the 
  air 
  or 
  in 
  vacuo 
  arose 
  from 
  vaporiza- 
  

   tion, 
  the 
  author 
  was 
  led 
  to 
  attempt 
  its 
  distillation. 
  A 
  quantity 
  

   of 
  the 
  commercial 
  peroxide 
  concentrated 
  until 
  it 
  contained 
  50 
  per 
  

   cent 
  of 
  H 
  2 
  2 
  , 
  was 
  purified 
  by 
  extraction 
  with 
  ether; 
  whereby 
  

   the 
  quantity 
  of 
  H 
  2 
  2 
  was 
  raised 
  to 
  73 
  per 
  cent. 
  On 
  submitting 
  

   this 
  to 
  distillation 
  on 
  the 
  water 
  bath 
  at 
  the 
  pressure 
  of 
  68 
  mm 
  of 
  

   mercury, 
  two 
  fractions 
  were 
  obtained, 
  the 
  one 
  boiling 
  at 
  7l°-81° 
  

   and 
  the 
  other 
  at 
  81°-85° 
  ; 
  the 
  former 
  containing 
  44 
  per 
  cent 
  H 
  2 
  2 
  

   and 
  the 
  latter 
  90*5 
  per 
  cent. 
  On 
  fractioning 
  again 
  the 
  latter 
  

   product, 
  a 
  distillate 
  was 
  obtained 
  at 
  84°-85° 
  which 
  contained 
  

   over 
  99 
  per 
  cent 
  of 
  H 
  2 
  2 
  and 
  was 
  practically 
  pure 
  peroxide. 
  It 
  

   is 
  a 
  colorless 
  syrupy 
  liquid, 
  which 
  'scarcely 
  wets 
  the 
  containing 
  

   vessel 
  and 
  which 
  evaporates 
  in 
  the 
  air. 
  It 
  produces 
  a 
  prickly 
  

   sensation 
  upon 
  the 
  skin, 
  causing 
  a 
  white 
  spot. 
  Even 
  after 
  distil- 
  

   lation 
  with 
  soda 
  it 
  reacts 
  strongly 
  acid. 
  Further 
  experiments 
  

   have 
  shown 
  that 
  the 
  treatment 
  with 
  ether 
  is 
  not 
  essential; 
  a 
  3 
  per 
  

   cent 
  solution 
  being 
  readily 
  concentrated 
  by 
  repeated 
  fractioning 
  

  

  