﻿THE 
  

  

  AMERICAN 
  JOURNAL 
  OF 
  SCIENCE 
  

  

  [FOURTH 
  SERIES.] 
  

  

  Art. 
  XXXYIII. 
  — 
  On 
  a 
  Method 
  of 
  Studying 
  the 
  Diffusion 
  

   {Transpiration) 
  of 
  Air 
  through 
  Water, 
  and 
  on 
  a 
  Method 
  of 
  

   Barometry 
  ; 
  by 
  C. 
  Barus. 
  

  

  1. 
  Small 
  bubbles 
  of 
  air 
  in 
  a 
  mass 
  of 
  liquid 
  gradually 
  

   vanish 
  in 
  the 
  lapse 
  of 
  time, 
  if 
  a 
  very 
  high 
  pressure 
  is 
  per- 
  

   sistently 
  maintained. 
  Air 
  forced 
  into 
  the 
  liquid 
  in 
  accordance 
  

   with 
  Henry's 
  law 
  diffuses 
  into 
  less 
  aerated 
  surroundings, 
  

   becomes 
  dissipated 
  and 
  too 
  far 
  diluted 
  to 
  reappear 
  on 
  removal 
  

   of 
  pressure. 
  The 
  experiment, 
  though 
  interesting, 
  does 
  not 
  

   lend 
  itself 
  to 
  computation. 
  

  

  I 
  purpose 
  in 
  the 
  following 
  to 
  describe 
  a 
  method 
  of 
  inducing 
  

   the 
  transpiration 
  of 
  air 
  through 
  a 
  wall 
  of 
  water 
  under 
  known 
  

   conditions, 
  seeing 
  that 
  few 
  data 
  on 
  this 
  subject 
  have 
  yet 
  been 
  

   investigated. 
  It 
  is 
  not 
  impossible 
  that 
  from 
  data 
  of 
  this 
  kind 
  

   one 
  may 
  estimate 
  the 
  degree 
  of 
  physical 
  porosity 
  of 
  the 
  liquid 
  ; 
  

   to 
  state, 
  in 
  other 
  words, 
  what 
  fraction 
  of 
  the 
  area 
  of 
  a 
  normal 
  

   interface 
  is 
  permeable, 
  and 
  what 
  fraction 
  impermeable 
  to 
  a 
  

   current 
  of 
  gas. 
  

  

  The 
  physical 
  laboratory 
  is 
  in 
  possession 
  of 
  a 
  Cartesian 
  diver, 
  

   made 
  by 
  Prof. 
  Blake 
  some 
  years 
  ago. 
  I 
  have 
  been 
  exhibiting 
  

   this 
  yearly 
  since 
  1895, 
  and 
  as 
  it 
  seems 
  to 
  me, 
  the 
  diver 
  has 
  

   been 
  becoming 
  steadily 
  heavier 
  in 
  this 
  course 
  of 
  years 
  : 
  at 
  

   least, 
  whereas 
  at 
  the 
  outset 
  the 
  diver 
  was 
  usually 
  afloat, 
  it 
  is 
  so 
  

   now 
  only 
  under 
  exceptionally 
  high 
  temperature 
  and 
  low 
  

   barometer. 
  The 
  question 
  therefore 
  occurs 
  whether 
  there 
  is 
  

   any 
  reason 
  for 
  the 
  loss 
  of 
  air 
  in 
  v 
  (see 
  figure), 
  if 
  the 
  top 
  of 
  the 
  

   jar 
  is 
  slightly 
  open 
  and 
  in 
  contact 
  with 
  the 
  atmosphere, 
  after 
  

   the 
  diver 
  has 
  been 
  permanently 
  sunk. 
  Clearly 
  such 
  a 
  reason 
  

   does 
  exist, 
  at 
  least 
  qualitatively, 
  for 
  the 
  air 
  in 
  v 
  is 
  under 
  atmos- 
  

   pheric 
  pressure 
  plus 
  the 
  additional 
  pressure 
  due 
  to 
  the 
  head 
  of 
  

  

  Am. 
  Jour. 
  Sci. 
  — 
  Fourth 
  Series, 
  Vol. 
  IX, 
  No. 
  54. 
  — 
  Juxe, 
  1900. 
  

   28 
  

  

  