400  Intelligence  and,  Miscellaneous  Articles. 
ing  traces  of  any  fatty  substance  whatever,  to  see  a  distinct  produc- 
tion of  minute  gas-bubbles. 
If  the  phial  containing  the  distilled  water  is  not  perfectly  cleared 
of  every  fatty  or  etherial  matter,  numerous  gas-bubbles  soon  form  at 
the  parts  of  the  inner  surface  to  which  that  matter  is  attached. 
II.  A  drop  of  oil  spreading  on  the  surface  of  distilled  water  pro- 
duces a  disengagement  of  little  gas-bubbles  readily  observed  with  a 
microscope  ;  this  disengagement  I  believe  to  be  the  true  cause  of  the 
formation  of  what  Mr.  Tomlinson  terms  cohesion-figures — that  is  to 
say,  of  the  division  of  the  spread  film  into  an  infinity  of  parts  con- 
stituting at  first  a  sort  of  network,  and  decomposing,  little  by  little, 
into  lenticles  of  less  and  less  dimensions,  until,  the  gaseous  disen- 
gagement ceasing,  the  minute  lenticles  remain  indefinitely.  With 
the  microscope  I  was  able  to  follow  all  the  phases  of  the  phenomenon, 
evidently  due  to  innumerable  minute  gas-bubbles  disengaged  beneath 
the  films. 
The  experiment  can  be  made  with  any  of  the  oils,  fixed  or  volatile, 
with  sulphide  of  carbon,  wood-spirit,  &c. 
When  any  oil  whatever  is  kept  in  prolonged  contact  with  water, 
the  surface  of  separation  of  the  two  liquids  soon  loses  its  transpa- 
rency. This  fact,  so  well  known,  is  explained  by  the  disengagement 
of  minute  gas-bubbles,  which  more  or  less  resinify  the  oil  and  unfit 
it  for  transmitting  light. 
III.  It  was  long  since  observed  that  water  commences  ebullition 
with  more  difficulty  the  better  it  is  freed  from  the  gases  it  holds  in 
solution.  What  precedes  enables  us  to  foresee  that  by  mixing  dis- 
tilled water  with  alcohol  a  great  quantity  of  the  dissolved  gases  can 
be  expelled.  This,  in  fact,  is  confirmed  by  an  experiment  recently 
made  by  M.  Kremers  :  having  added  one  part  of  spirit  of  wine  to 
three  parts  of  water  and  strongly  heated,  he  saw  the  boiling-point 
readily  rise  to  109°  C,  and  even  far  beyond,  according  to  the  pro- 
portion of  the  volatile  liquid  evaporated.  I  regard  this  experiment 
as  a  very  curious  verification  of  my  principle. 
Liquids  of  feeble  tension  favour  the  disengagement  of  bubbles 
of  vapour  as  well  as  of  gas ;  this  is  demonstrated  by  the  striking 
experiments  of  Mr.  Tomlinson.  He  has  observed  that  greasy  bodies 
prevent  "  soubresauts"  while  solid  bodies  perfectly  free  from  grease 
do  not  at  all  produce  the  same  effect. 
IV-.  It  is  known  that  the  Brownian  or  molecular  movements  are 
produced  most  energetically  in  a  mixture  of  distilled  water  and  any 
volatile  liquid  :  in  this  case  the  movements  appear  to  me  to  be  a  very 
plain  consequence  of  my  general  proposition.  As  to  their  existence 
in  a  homogeneous  liquid,  we  require  to  know  whether  the  microscopic 
particles  whose  feeble  trepidations  have  been  seen  were  not  more  or 
less  greasy  ;  in  that  case  they  would  necessarily  give  rise  to  a  gaseous 
discharge,  and  consequently  change  their  position  from  time  to  time. 
If  the  corpuscles  are  absolutely  pure,  they  cannot  manifest  the  little 
movements  in  question  ;  moreover  several  observers  have  never  been 
able  to  verify  the  Brownian  displacements  in  a  homogeneous  liquid. 
—Bull,  de  VAcad.  Roy.  de  Belgique,  S.  2.  vol.  xxiii.  No.  3  :   1872. 
MAH  37  im 
