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  XXXIII. 
  Tlie 
  Viscosity 
  of 
  Water. 
  By 
  Richard 
  Hosking, 
  

   B.A. 
  (Camb.), 
  Physics 
  Master, 
  Sydney 
  Graynmar 
  ScJiool*, 
  

  

  IN 
  a 
  paper 
  recently 
  published 
  f 
  in 
  the 
  Philosophical 
  

   Magazine 
  I 
  explained 
  how 
  I 
  had 
  obtained 
  three 
  absolute 
  

   values 
  for 
  the 
  viscosity 
  o£ 
  water 
  at 
  different 
  temperatures. 
  

   I 
  have 
  since 
  examined 
  my 
  reductions 
  more 
  carefully, 
  and 
  

   have 
  found 
  that 
  the 
  values 
  are, 
  in 
  c.G.s. 
  units, 
  '005500 
  at 
  

   50° 
  C, 
  -008926 
  at 
  25° 
  C, 
  and 
  '017897 
  at 
  0°-05 
  G. 
  The 
  last 
  

   value 
  reduces 
  to 
  '017928 
  at 
  0° 
  C. 
  

  

  KnibbsJ 
  has 
  deduced 
  the 
  absolute 
  value 
  '013107 
  at 
  10° 
  C. 
  

   from 
  Poiseuille's 
  observations, 
  and 
  has 
  shown 
  that 
  the 
  data 
  

   o£ 
  every 
  other 
  experimenter 
  whose 
  work 
  was 
  published 
  

   earlier 
  than 
  1895, 
  including 
  Thorpe 
  and 
  Rodger, 
  were 
  not 
  

   satisfactory 
  for 
  absolute 
  values. 
  So 
  far 
  as 
  I 
  have 
  been 
  able 
  

   to 
  examine 
  the 
  work 
  published 
  since 
  1895, 
  I 
  have 
  reached 
  a 
  

   similar 
  conclusion 
  with 
  regard 
  to 
  it. 
  

  

  In 
  order, 
  therefore, 
  to 
  obtain, 
  if 
  possible, 
  a 
  complete 
  table 
  

   of 
  absolute 
  values 
  between 
  the 
  temperatures 
  Q° 
  C. 
  and 
  100° 
  C. 
  

   I 
  have 
  revised 
  all 
  my 
  earlier 
  work§, 
  and 
  reduced 
  my 
  obser- 
  

   vations 
  again 
  by 
  applying 
  in 
  the 
  reduction 
  formula, 
  as 
  given 
  

   in 
  my 
  last 
  paper, 
  the 
  value 
  ??i 
  = 
  1*158 
  ||, 
  instead 
  of 
  ??i=l'000, 
  

   which 
  I 
  had 
  previously 
  used, 
  and 
  the 
  value 
  n 
  = 
  l'64 
  1[. 
  My 
  

   results 
  obtained 
  in 
  this 
  way 
  are 
  contained 
  in 
  Table 
  A. 
  Each 
  

   value 
  is 
  obtained 
  by 
  the 
  reduction 
  of 
  double 
  sets 
  of 
  observa- 
  

   tions. 
  The 
  table 
  contains 
  also 
  the 
  kinetic-energy 
  correction 
  

   in 
  each 
  case. 
  The 
  values 
  are 
  reduced 
  to 
  even 
  temperatures 
  

   by 
  means 
  of 
  the 
  formulae 
  to 
  be 
  given 
  in 
  Table 
  B 
  (p. 
  2^2), 
  which 
  

   reproduce 
  the 
  observed 
  values 
  with 
  remarkable 
  closeness. 
  

   It 
  is 
  this 
  fact 
  which 
  justifies 
  the 
  method. 
  

  

  These 
  values 
  agree 
  with 
  the 
  absolute 
  values 
  at 
  the 
  tempe- 
  

   ratures 
  0° 
  C, 
  10 
  C, 
  50° 
  C, 
  and 
  also 
  (by 
  interpolation) 
  at 
  

   25° 
  C, 
  and 
  it 
  is 
  reasonable 
  to 
  suppose 
  that 
  at 
  the 
  other 
  

   temperatures 
  also 
  they 
  are 
  the 
  correct 
  absolute 
  values. 
  From 
  

   the 
  graph, 
  values 
  at 
  the 
  odd 
  5 
  degrees, 
  for 
  which 
  there 
  were 
  

   no 
  experiments, 
  were 
  obtained 
  very 
  carefully. 
  

  

  * 
  Communicated 
  by 
  tlie 
  Author. 
  Read 
  before 
  the 
  Royal 
  Society 
  of 
  

   Ts\ 
  S. 
  Wales. 
  

  

  t 
  Phil. 
  Mag. 
  April 
  1909. 
  

  

  \ 
  Journal 
  and 
  Proceedings 
  of 
  the 
  Royal 
  Society 
  of 
  N. 
  S. 
  Wales, 
  

   -vol. 
  xxxi. 
  

  

  § 
  Phil. 
  Mag. 
  March 
  1900, 
  I^tay 
  1902, 
  May 
  1904. 
  

  

  II 
  Boussinesq's 
  theoretical 
  correction 
  is 
  1-12, 
  but 
  experimentally 
  I 
  

   obtained 
  the 
  average 
  value 
  1-158 
  for 
  four 
  tubes, 
  which 
  had 
  been 
  treated 
  

   in 
  exactly 
  the 
  same 
  way 
  as 
  those 
  used 
  in 
  these 
  earlier 
  experiments. 
  

  

  ^ 
  For' 
  these 
  tubes 
  n 
  seems 
  to 
  have 
  the 
  value 
  1*64, 
  for 
  with 
  that 
  value 
  

   inserted, 
  the 
  reduced 
  values 
  for 
  viscosity 
  at 
  0^ 
  C, 
  10° 
  C, 
  and 
  50° 
  C. 
  

   agree 
  vp^ith 
  the 
  absolute 
  values 
  at 
  those 
  temperatures 
  as 
  given 
  at 
  the 
  

   beginning 
  of 
  this 
  paper. 
  

  

  