Intelligence  and  Miscellaneous  Articles.  317 
out  tube ;  the  air  contained  in  it  penetrates  and  ascends  in  the 
liquid.  The  experiment,  repeated  several  times,  always  gave  the 
same  result. 
Let  us  now  assume  that  at  a  certain  distance  below  the  surface  of 
the  suspended  water  there  is  a  current  of  visible  aqueous  vapour  ; 
if  this  vapour  consists  of  vesicles,  each  of  them,  on  coming  into  contact 
with  the  fluid  surface,  will  introduce  a  microscopic  air-bubble  into 
the  water,  which  will  immediately  ascend  in  it;  and  the  whole  of  these 
vesicles  will  form  a  cloud  in  the  water  of  the  tube,  which  slowly 
rises  and  destroys  the  transparency. 
M.  Duprez  was  good  enough  to  make  the  experiment  at  my  re- 
quest. The  water  was  suspended  in  a  glass  tube  of  13  millims.  in- 
ternal diameter.  A  small  metal  vessel  with  an  aperture  of  several 
centimetres  diameter  and  containing  a  certain  quantity  of  water, 
was  placed  under  the  free  surface  of  the  water  of  the  tube  over  a 
lamp;  the  mouth  of  this  vessel  was  about  12  centims.  from  the  sur- 
face. A  continuous  boiling  was  thus  obtained,  and  a  current  of 
visible  vapour  which  rose  to  the  surface  of  the  suspended  water  ;  but 
though  the  experiment  lasted  more  than  half  an  hour,  no  cloud  was 
observed  in  the  water  of  the  tube.  The  vapour  condensed  on  the 
outside  of  the  tube,  and  from  time  to  time  was  wiped  away ;  but 
the  water  inside  retained  all  its  transparency. 
After  this  it  seems  difficult  to  retain  any  doubt  as  to  the  non- 
existence of  the  vesicular  state.  It  seems  to  me,  in  fact,  that  only 
three  objections  could  here  be  raised.  It  might  either  be  said  that 
the  air-bubbles  on  penetrating  into  the  water,  from  their  unusual 
smallness  and  the  very  considerable  capillary  pressure  which  they 
have  to  support  from  the  liquid,  dissolve  in  the  liquid,  or  that  nil 
vesicles  burst  on  reaching  the  surface  of  the  water,  or  that  they  roll 
along  the  surface  of  this  liquid,  separated  from  it  by  a  thin  layer  of 
air  or  vapour,  until  they  reach  the  outside  edge  of  the  tube  to 
escape  thence  into  the  atmosphere. 
But  the  first  of  these  assumptions  must  be  rejected  ;  for  the  water 
had  previously  been  shaken  with  air  so  long  as  to  be  completely 
saturated,  and,  secondly,  while  it  was  exposed  to  the  action  of  vapour 
it  must  have  lost  whatever  solvent  power  it  possessed ;  and,  more- 
over, sometimes  even  comparatively  large  air-bubbles  appear  on  the 
upper  part  of  the  inside  of  the  tube,  where  the  hotter  part  of  the 
water  ascends. 
The  second  supposition,  though  not  quite  inadmissible,  is  at  any 
rate  not  very  probable.  We  have  seen  that  our  small  bubbles,  mea- 
suring less  than  a  millimetre,  do  not  burst  on  coming  into  contact  with 
the  surface  of  water  ;  why  should  it  be  otherwise  with  the  vesicles  ? 
It  may  perhaps,  be  urged  that  their  envelope  is  far  thinner  than 
that  of  our  small  bubbles.  But  if  vesicles  exist,  their  envelope 
must  be  so  thick  that  they  are  colourless ;  otherwise  a  cloud  irra- 
diated by  the  sun  could  have  no  bright  lustre  ;  moreover,  from  the 
long  duration  of  large  clouds,  they  must  be  very  permanent. 
As  regards  the  third  supposition,  is  it  probable  that  all  vesicles 
could  roll  along  the  surface  without  touching  ?    Moreover  M.  Duprez 
