﻿416 
  Scientific 
  Intelligence. 
  

  

  SCIENTIFIC 
  INTELLIGENCE. 
  

  

  I. 
  Chemistry 
  and 
  Physics. 
  

  

  1. 
  On 
  the 
  Hotation 
  of 
  Circularly 
  Polarizing 
  Crystals 
  in 
  the 
  

   State 
  of 
  Poioder. 
  — 
  It 
  has 
  been 
  shown 
  by 
  Landolt 
  that 
  the 
  spe- 
  

   cific 
  rotation 
  of 
  isotropic 
  circularly 
  polarizing 
  crystalline 
  sub- 
  

   stances, 
  in 
  a 
  state 
  of 
  powder, 
  may 
  be 
  determined 
  in 
  an 
  ordinary 
  

   polarimeter 
  tube, 
  by 
  suspending 
  the 
  finely 
  divided 
  material 
  in 
  a 
  

   liquid 
  having 
  the 
  same 
  refractive 
  index 
  and 
  then 
  measuring 
  the 
  

   angle 
  through 
  which 
  the 
  plane 
  of 
  polarization 
  of 
  the 
  entering 
  

   beam 
  is 
  turned. 
  For 
  the 
  best 
  result, 
  the 
  substance 
  should 
  be 
  

   pulverized 
  in 
  an 
  agate 
  mortar 
  and 
  then 
  sifted, 
  so 
  as 
  to 
  obtain 
  par- 
  

   ticles 
  of 
  from 
  0*004 
  to 
  0'012 
  mm 
  in 
  diameter 
  ; 
  and 
  while 
  the 
  measure- 
  

   ments 
  are 
  being 
  made 
  the 
  polarimeter 
  tube 
  should 
  be 
  constantly 
  

   rotated, 
  so 
  as 
  to 
  keep 
  the 
  particles 
  uniformly 
  suspended. 
  The 
  

   speed 
  of 
  rotation 
  should 
  preferably 
  be 
  between 
  50 
  and 
  80 
  revolu- 
  

   tions 
  per 
  minute, 
  since 
  at 
  higher 
  velocities 
  the 
  particles 
  of 
  the 
  

   solid 
  are 
  driven 
  by 
  centrifugal 
  action 
  to 
  the 
  sides 
  of 
  the 
  tube, 
  

   leaving 
  the 
  central 
  portions 
  more 
  or 
  less 
  empty 
  of 
  them. 
  The 
  

   direction 
  of 
  rotation 
  of 
  the 
  tube 
  is 
  immaterial. 
  The 
  author's 
  

   experiments 
  were 
  made 
  with 
  both 
  right 
  and 
  left-handed 
  sodium 
  

   chlorate, 
  from 
  0*1 
  to 
  - 
  3 
  gram 
  of 
  the 
  powder 
  being 
  placed 
  in 
  

   a 
  test 
  tube 
  with 
  alcohol, 
  carbon 
  disulphide 
  being 
  gradually 
  

   added 
  until 
  the 
  maximum 
  transparency 
  was 
  reached; 
  this 
  requir- 
  

   ing 
  about 
  two 
  volumes 
  of 
  the 
  disulphide 
  to 
  one 
  of 
  alcohol. 
  The 
  

   mixture 
  was 
  then 
  placed 
  in 
  the 
  tube 
  of 
  the 
  polarimeter 
  and 
  the 
  

   angle 
  of 
  rotation 
  measured. 
  To 
  determine 
  the 
  amount 
  of 
  solid, 
  

   the 
  contents 
  of 
  the 
  tube 
  were 
  placed 
  in 
  a 
  platinum 
  dish, 
  evapo- 
  

   rated 
  to 
  dryness 
  and 
  the 
  residue 
  weighed. 
  In 
  this 
  way 
  the 
  

   specific 
  rotation 
  of 
  the 
  sodium 
  chlorate 
  in 
  powder 
  was 
  found 
  to 
  

   be 
  [a],- 
  = 
  ± 
  1 
  '4 
  1 
  ° 
  ; 
  while 
  that 
  of 
  the 
  crystals 
  is 
  given 
  as 
  1*42° 
  for 
  

   l 
  ram 
  , 
  practically 
  the 
  same 
  value. 
  Hence 
  it 
  appears 
  that 
  particles 
  

   of 
  this 
  salt 
  having 
  a 
  diameter 
  of 
  from 
  0'004 
  to 
  0-0l2 
  mm 
  possess 
  

   the 
  same 
  crystalline 
  structure 
  as 
  that 
  to 
  which 
  the 
  circular 
  polari- 
  

   zation 
  of 
  the 
  larger 
  and 
  completely 
  formed 
  crystals 
  is 
  due. 
  — 
  Ber. 
  

   Perl. 
  Chem. 
  Ges., 
  xxix, 
  2404-2412, 
  October, 
  1896. 
  g. 
  f. 
  b. 
  

  

  2. 
  On 
  the 
  Oxidation 
  of 
  Nitrogen 
  Gas. 
  — 
  In 
  his 
  experiments 
  

   upon 
  the 
  isolation 
  of 
  argon, 
  Rayleigh 
  made 
  some 
  observations 
  

   upon 
  the 
  oxidation 
  of 
  nitrogen, 
  which 
  he 
  has 
  communicated 
  to 
  

   the 
  Chemical 
  Society. 
  His 
  first 
  experiments 
  were 
  made 
  to 
  test 
  

   the 
  statement 
  of 
  Davy 
  that 
  the 
  dissolved 
  nitrogen 
  in 
  water 
  is 
  

   oxidized 
  to 
  nitrous 
  or 
  nitric 
  acid 
  when 
  the 
  liquid 
  is 
  submitted 
  to 
  

   electrolysis. 
  The 
  water 
  was 
  contained 
  in 
  two 
  cavities 
  bored 
  in 
  a 
  

   block 
  of 
  paraffin 
  and 
  connected 
  by 
  a 
  wick 
  of 
  asbestos 
  previously 
  

   ignited. 
  By 
  means 
  of 
  platinum 
  terminals 
  connected 
  with 
  a 
  sec- 
  

   ondary 
  battery 
  a 
  difference 
  of 
  potential 
  of 
  100 
  volts 
  was 
  main- 
  

   tained 
  in 
  the 
  cells, 
  the 
  whole 
  being 
  covered 
  with 
  a 
  glass 
  shade. 
  

   But 
  under 
  these 
  conditions, 
  litmus 
  showed 
  no 
  difference 
  between 
  

  

  