﻿Chemistry 
  and 
  Physics. 
  375 
  

  

  SCIENTIFIC 
  INTELLIGENCE. 
  

  

  I. 
  Chemistry 
  and 
  Physics. 
  

  

  1. 
  On 
  the 
  Viscosity 
  of 
  Argon 
  as 
  affected 
  by 
  Temperature. 
  — 
  

   Lord 
  Ratleigh 
  has 
  carried 
  on 
  a 
  series 
  of 
  experiments 
  on 
  the 
  

   above 
  subject, 
  special 
  interest 
  being 
  connected 
  with 
  it 
  since 
  

   argon 
  as 
  regards 
  specific 
  heat 
  behaves 
  as 
  if 
  monatornic. 
  The 
  

   author 
  says 
  : 
  

  

  " 
  When 
  we 
  remember 
  that 
  the 
  principal 
  gases, 
  such 
  as 
  oxygen, 
  

   hydrogen, 
  and 
  nitrogen, 
  are 
  regarded 
  as 
  diatomic, 
  we 
  may 
  be 
  

   inclined 
  to 
  attribute 
  the 
  want 
  of 
  simplicity 
  in 
  the 
  law 
  connecting 
  

   viscosity 
  and 
  temperature 
  to 
  the 
  complication 
  introduced 
  by 
  the 
  

   want 
  of 
  symmetry 
  in 
  the 
  molecules 
  and 
  consequent 
  diversities 
  of 
  

   presentation 
  in 
  an 
  encounter. 
  It 
  was 
  with 
  this 
  idea 
  that 
  I 
  thought 
  

   it 
  would 
  be 
  interesting 
  to 
  examine 
  the 
  influence 
  of 
  temperature 
  

   upon 
  the 
  viscosity 
  of 
  argon, 
  which 
  in 
  the 
  matter 
  of 
  specific 
  heat 
  

   behaves 
  as 
  if 
  composed 
  of 
  single 
  atoms. 
  From 
  the 
  fact 
  that 
  no 
  

   appreciable 
  part 
  of 
  the 
  total 
  energy 
  is 
  rotatory, 
  we 
  may 
  infer 
  

   that 
  the 
  forces 
  called 
  into 
  play 
  during 
  an 
  encounter 
  are 
  of 
  a 
  

   symmetrical 
  character. 
  It 
  seemed, 
  therefore, 
  more 
  likely 
  that 
  a 
  

   simple 
  relation 
  between 
  viscosity 
  and 
  temperature 
  would 
  obtain 
  

   in 
  the 
  case 
  of 
  argon 
  than 
  in 
  the 
  case 
  of 
  the 
  " 
  diatomic 
  " 
  gases. 
  

  

  The 
  best 
  experimental 
  arrangement 
  for 
  examining 
  this 
  ques- 
  

   tion 
  is 
  probably 
  that 
  of 
  Holman,* 
  in 
  which 
  the 
  same 
  constant 
  

   stream 
  of 
  gas 
  passes 
  in 
  succession 
  through 
  two 
  capillaries 
  at 
  dif- 
  

   ferent 
  temperatures, 
  the 
  pressures 
  being 
  determined 
  before 
  the 
  

   first 
  and 
  after 
  the 
  second 
  passage, 
  as 
  well 
  as 
  between 
  the 
  two. 
  

   But 
  to 
  a 
  gas 
  like 
  argon, 
  available 
  in 
  small 
  quantities 
  only, 
  the 
  

   application 
  of 
  this 
  method 
  is 
  difficult. 
  And 
  it 
  seemed 
  unneces- 
  

   sary 
  to 
  insist 
  upon 
  the 
  use 
  of 
  constant 
  pressures, 
  seeing 
  that 
  it 
  

   was 
  not 
  proposed 
  to 
  investigate 
  experimentally 
  the 
  dependence 
  of 
  

   transpiration 
  upon 
  pressure." 
  . 
  . 
  . 
  

  

  " 
  Although 
  different 
  gases 
  have 
  been 
  employed 
  in 
  the 
  present 
  

   experiments, 
  there 
  has 
  been 
  no 
  attempt 
  to 
  compare 
  their 
  viscos- 
  

   ities, 
  and 
  indeed 
  such 
  a 
  comparison 
  would 
  be 
  difficult 
  to 
  carry 
  

   out 
  by 
  this 
  method. 
  The 
  question 
  has 
  been, 
  how 
  is 
  the 
  viscosity 
  

   of 
  a 
  given 
  gas 
  affected 
  by 
  a 
  change 
  of 
  temperature 
  ? 
  In 
  one 
  set 
  

   of 
  experiments 
  the 
  capillary 
  is 
  at 
  the 
  temperature 
  of 
  the 
  room 
  ; 
  

   in 
  a 
  closely 
  following 
  set 
  the 
  capillary 
  is 
  bathed 
  in 
  saturated 
  

   steam 
  at 
  a 
  temperature 
  that 
  can 
  be 
  calculated 
  from 
  the 
  height 
  of 
  

   the 
  barometer." 
  

  

  In 
  the 
  experiments 
  the 
  times 
  of 
  transpiration 
  were 
  found 
  to 
  be 
  

   104*67 
  seconds 
  at 
  the 
  temperature 
  of 
  the 
  room 
  (15°) 
  and 
  167*58 
  

   at 
  100°*27. 
  The 
  relation 
  between 
  the 
  times 
  of 
  transpiration 
  (t) 
  

   and 
  the 
  absolute 
  temperatures 
  (0) 
  is 
  given 
  by 
  the 
  equation 
  

  

  whence 
  is 
  obtained 
  the 
  value 
  x 
  = 
  1*812. 
  As 
  the 
  

  

  * 
  Phil. 
  Mag., 
  vol. 
  iii, 
  p. 
  81, 
  1877. 
  

  

  Hr)'. 
  

  

  