﻿of 
  Mercury 
  in 
  the 
  Lapse 
  of 
  Time. 
  141 
  

  

  question, 
  thus 
  admitting 
  of 
  a 
  considerable 
  contact 
  angle. 
  I 
  am 
  

   unable, 
  however, 
  to 
  find 
  satisfactory 
  data 
  for 
  the 
  stresses 
  in 
  

   question 
  ; 
  but 
  it 
  is 
  probable 
  from 
  the 
  large 
  values 
  of 
  surface 
  

   tension 
  involved 
  that 
  the 
  rate 
  at 
  which 
  water 
  is 
  withdrawn 
  

   between 
  mercury 
  and 
  glass 
  is 
  more 
  rapid 
  than 
  the 
  motions 
  of 
  

   the 
  thread 
  instanced 
  above. 
  The 
  problem, 
  therefore, 
  now 
  

   assumes 
  a 
  somewhat 
  different 
  form, 
  namely, 
  to 
  so 
  wet 
  the 
  

   glass 
  by 
  moving 
  the 
  mercury 
  thread 
  as 
  to 
  favor 
  a 
  supply 
  of 
  

   film 
  between 
  mercury 
  and 
  glass. 
  I 
  tried 
  many 
  methods 
  to 
  

   accomplish 
  this. 
  They 
  were 
  all 
  negative 
  as 
  to 
  results, 
  and 
  1 
  

   will, 
  therefore, 
  merely 
  describe 
  one. 
  The 
  capillary 
  tube 
  AB 
  

   (above 
  figure), 
  # 
  0S 
  cm 
  in 
  diameter, 
  surmounted 
  by 
  a 
  cistern 
  A, 
  

   was 
  provided 
  at 
  its 
  lower 
  end 
  with 
  a 
  bulb 
  C 
  '(l*2 
  cm 
  in 
  diameter, 
  

   4-5 
  cm 
  long), 
  large 
  enough 
  to 
  displace 
  the 
  thread 
  M 
  throughout 
  

   its 
  length 
  (about 
  3*5 
  cm 
  ) 
  by 
  reasonably 
  heating 
  the 
  bulb 
  in 
  water 
  

   baths 
  (18° 
  to 
  40°). 
  A 
  millimeter 
  scale 
  was 
  attached 
  to 
  the 
  

   stem 
  and 
  read 
  off 
  with 
  a 
  telescope. 
  The 
  tube 
  was 
  first 
  placed 
  

   in 
  a 
  special 
  water 
  bath 
  of 
  constant 
  temperature 
  (about 
  18°), 
  

   and 
  the 
  position 
  of 
  the 
  thread 
  taken 
  while 
  a 
  sensitive 
  ther- 
  

   mometer 
  indicated 
  the 
  temperature 
  of 
  the 
  bath. 
  The 
  tube 
  

   was 
  now 
  removed 
  and 
  submerged 
  successively 
  in 
  the 
  two 
  

   auxiliary 
  water 
  baths 
  in 
  question. 
  In 
  this 
  way 
  the 
  thread 
  was 
  

   kept 
  in 
  continual 
  motion 
  at 
  an 
  average 
  rate 
  of 
  about 
  a 
  centi- 
  

   meter 
  in 
  10 
  sec, 
  the 
  operation 
  being 
  prolonged 
  throughout 
  

   3,000 
  seconds. 
  Finally 
  the 
  tube 
  was 
  returned 
  to 
  the 
  normal 
  

   water 
  bath 
  and 
  the 
  position 
  of 
  the 
  thread 
  read 
  off 
  at 
  the 
  tem- 
  

   perature 
  given 
  by 
  the 
  sensitive 
  thermometer. 
  The 
  bulb 
  itself 
  

   showed 
  about 
  *2 
  cm 
  per 
  degree 
  C, 
  thus 
  admitting 
  of 
  corrections. 
  

   The 
  results 
  indicate 
  a 
  fall 
  of 
  less 
  than 
  -05 
  cm 
  for 
  the 
  3000 
  sec- 
  

   onds 
  of 
  motion. 
  Inserting 
  the 
  superior 
  limit 
  in 
  the 
  above 
  

   equation, 
  a 
  film 
  having 
  average 
  thickness 
  of 
  Sr 
  <6XlO 
  _10cn:i 
  is 
  

   deduced, 
  in 
  spite 
  of 
  the 
  continued 
  motion 
  of 
  the 
  thread. 
  This 
  

   result, 
  as 
  absurdly 
  small 
  as 
  the 
  corresponding 
  datum 
  in 
  § 
  1, 
  

   shows 
  the 
  effect 
  of 
  motion 
  of 
  the 
  kind 
  applied 
  to 
  be 
  insignifi- 
  

   cant. 
  

  

  4. 
  Finally 
  the 
  endeavor 
  was 
  to 
  be 
  made 
  to 
  study 
  the 
  effects 
  

   due 
  to 
  the 
  volume 
  viscosity 
  of 
  glass. 
  The 
  bulb 
  of 
  the 
  above 
  

   piezometer 
  being 
  35 
  cm3 
  in 
  capacity, 
  a 
  promising 
  method 
  would 
  

   consist 
  in 
  reducing 
  the 
  volume 
  to 
  a 
  very 
  small 
  value. 
  Accord- 
  

   ingly 
  two 
  tubes 
  (Nos. 
  II 
  and 
  III) 
  with 
  bulbs 
  *25 
  cub 
  cm 
  and 
  

   •40 
  cub 
  cm 
  in 
  capacity, 
  and 
  stems 
  respectively 
  'l 
  cm 
  and 
  -2 
  cm 
  in 
  

   diameter, 
  were 
  selected. 
  These 
  were 
  filled 
  with 
  pure 
  water 
  

   and 
  a 
  short 
  thread 
  of 
  mercury 
  (4-7 
  cm 
  and 
  4*2 
  long 
  in 
  the 
  two 
  

   cases), 
  inserted 
  under 
  water 
  near 
  the 
  open 
  ends 
  of 
  each. 
  The 
  

   tubes 
  were 
  now 
  provided 
  with 
  glass 
  millimeter 
  scales 
  and 
  a 
  

   thermometer, 
  and 
  then 
  completely 
  submerged 
  in 
  pure 
  water 
  

   contained 
  in 
  a 
  long 
  stand 
  glass, 
  closed 
  with 
  a 
  rubber 
  cork. 
  

  

  