﻿Chemistry 
  and 
  Physics, 
  71 
  

  

  8. 
  Rontgen 
  Rays. 
  — 
  Mr. 
  John 
  Macintyre 
  in 
  Nature, 
  Nov. 
  18, 
  

   1896, 
  gives 
  an 
  interesting 
  account 
  of 
  Lis 
  experiments 
  with 
  these 
  

   rays. 
  He 
  obtained 
  lantern 
  slides 
  of 
  X-ray 
  photographs 
  by 
  focus- 
  

   ing 
  the 
  shadow 
  on 
  the 
  fluoroscope 
  screen 
  on 
  the 
  ground-glass 
  

   screen 
  of 
  an 
  ordinary 
  camera. 
  In 
  addition 
  to 
  the 
  reduced 
  pic- 
  

   ture 
  of 
  the 
  shadow, 
  he 
  obtained 
  also 
  a 
  picture 
  of 
  the 
  brass 
  mount- 
  

   ings 
  and 
  lens 
  of 
  the 
  camera. 
  Hence 
  a 
  sufficient 
  number 
  of 
  X-rays 
  

   had 
  passed 
  through 
  the 
  screen 
  to 
  form 
  a 
  shadow 
  picture 
  of 
  those 
  

   objects. 
  It 
  appears 
  that 
  we 
  are 
  not 
  utilizing 
  all 
  the 
  X-rays 
  that 
  

   are 
  ordinarily 
  produced. 
  The 
  author 
  therefore 
  has 
  advantage- 
  

   ously 
  employed 
  a 
  large 
  and 
  thick 
  screen 
  in 
  which 
  the 
  crystals 
  

   of 
  the 
  fluorescent 
  substance 
  are 
  very 
  much 
  coarser 
  than 
  those 
  

   ordinarily 
  employed. 
  He 
  confirms 
  the 
  report 
  of 
  previous 
  ob- 
  

   servers 
  on 
  the 
  effect 
  of 
  the 
  Rontgen 
  rays 
  in 
  producing 
  inflamma- 
  

   tion 
  of 
  the 
  skin. 
  The 
  hand 
  after 
  being 
  long 
  exposed 
  to 
  their 
  

   effect 
  looks 
  as 
  if 
  it 
  had 
  been 
  sunburned 
  ; 
  becomes 
  red 
  and 
  swollen, 
  

   and 
  the 
  severer 
  effects 
  remain 
  for 
  a 
  fortnight. 
  j. 
  t. 
  

  

  9. 
  Rotation 
  in 
  Constant 
  Electric 
  Fields. 
  — 
  In 
  a 
  very 
  extended 
  

   paper, 
  Quincke 
  gives 
  the 
  results 
  of 
  his 
  observations 
  on 
  the 
  move- 
  

   ments 
  of 
  a 
  large 
  number 
  of 
  solid 
  dielectrics 
  immersed 
  in 
  fluid 
  

   dielectrics, 
  between 
  the 
  plates 
  of 
  a 
  condenser. 
  The 
  constant 
  

   electric 
  field 
  was 
  obtained 
  by 
  the 
  use 
  of 
  a 
  Piante 
  battery 
  of 
  

   twelve 
  hundred 
  cells. 
  The 
  author 
  gives 
  a 
  minute 
  description 
  of 
  

   the 
  method 
  of 
  construction 
  of 
  this 
  battery. 
  He 
  attributes 
  the 
  

   rotations 
  of 
  the 
  solid 
  dielectrics 
  to 
  the 
  difference 
  between 
  the 
  

   dielectric 
  constant 
  of 
  the 
  layers 
  of 
  air 
  adhering 
  to 
  the 
  rotating 
  

  

  bodies 
  and 
  the 
  dielectric 
  constants 
  of 
  the 
  bodies 
  themselves. 
  

  

  Ann. 
  der 
  Physik 
  und 
  Chemie, 
  No. 
  11, 
  1896, 
  pp. 
  417-486. 
  j. 
  t. 
  

  

  10. 
  Interferential 
  refractor 
  for 
  electrical 
  waves. 
  — 
  O. 
  Wiedeburg 
  

   employs 
  an 
  apparatus 
  for 
  obtaining 
  a 
  difference 
  of 
  path 
  which 
  is 
  

   analogous 
  to 
  that 
  used 
  by 
  Jamin 
  in 
  his 
  interferential 
  refractor. 
  

   Righi's 
  apparatus 
  for 
  exciting 
  and 
  detecting 
  short 
  wave-lengths 
  

   of 
  electricity 
  was 
  employed. 
  The 
  author 
  obtained 
  for 
  the 
  index 
  

   of 
  parafline, 
  w=l'418; 
  for 
  that 
  of 
  glass, 
  ^ 
  = 
  2*63. 
  — 
  Ann. 
  der 
  

   Physik 
  und 
  Chemie, 
  No. 
  11, 
  J 
  896, 
  pp. 
  498-522. 
  j. 
  t. 
  

  

  11. 
  The 
  Cadmium 
  normal 
  element. 
  — 
  In 
  a 
  communication 
  from 
  

   the 
  Physikalisch-Technische 
  Reichsanstalt, 
  W. 
  Jaeger 
  and 
  R. 
  

   Wachsmuth 
  give 
  a 
  careful 
  determination 
  of 
  the 
  temperature 
  

   coefficient 
  of 
  the 
  new 
  Weston 
  cell. 
  They 
  found 
  that 
  the 
  change 
  

   of 
  electromotive 
  force 
  of 
  the 
  Weston 
  cell, 
  with 
  a 
  change 
  ol 
  room 
  

   temperature 
  of 
  1° 
  C, 
  was 
  only 
  y^Vir 
  P 
  er 
  cent, 
  while 
  with 
  the 
  

   Clark 
  cell 
  it 
  is 
  ^ 
  per 
  cent. 
  In 
  reference 
  to 
  constancy 
  and 
  ease 
  of 
  

   reproduction 
  it 
  is 
  not 
  inferior 
  to 
  the 
  Clark 
  cell. 
  Its 
  electromotive 
  

   force 
  is 
  1*0184 
  volts. 
  In 
  the 
  Clark 
  element 
  there 
  is 
  sometimes 
  

   formed 
  a 
  layer 
  of 
  gas 
  over 
  the 
  zinc 
  amalgam, 
  which 
  raises 
  the 
  

   layer 
  of 
  zinc 
  sulphate 
  crystals, 
  and 
  therefore 
  increases 
  in 
  a 
  

   marked 
  manner 
  the 
  resistance 
  of 
  the 
  element. 
  Together 
  with 
  

   this 
  results 
  a 
  change 
  of 
  electromotive 
  force. 
  This 
  defect 
  does 
  

   not 
  enter 
  in 
  the 
  use 
  of 
  the 
  Weston 
  cell, 
  if 
  the 
  cadmium 
  sulphate 
  

   is 
  removed 
  by 
  free 
  acid. 
  — 
  Ann. 
  der 
  Physik 
  und 
  Chemie, 
  pp. 
  575- 
  

   591, 
  No. 
  11, 
  1896. 
  j. 
  t. 
  

  

  