408  The  Cohesion-Figures  of  Oils,  etc.  {^HiSf** 
are  not  larger  than  oil  of  nutmeg  at  one  and  a  half  minutes.  At  first 
they  have  a  dotted  border,  but  as  they  increase  in  size  this  changes 
to  a  scalloped  film,  which  spreads  until,  in  eight  or  ten  minutes,  they 
are  joined  together  over  the  whole  surface. 
This,  with  turpentine  oil,  gives  a  watered  surface  in  spreading,, 
much  more  marked  and  with  a  finer  play  of  colors. 
Experiments  with  fixed  oils  are  as  follows  :  poppy-seed  oil  spreads 
instantly  to  a  large  figure,  retaining  an  entire  outline,  and  for  a  few 
seconds  the  surface  is  unbroken,  except  the  bare  intimation  of  a 
beaded  edge.  In  a  few  moments  little  holes  appear  around  the  edge 
and  soon  the  whole  surface  is  broken  in  like  manner,  these  increase 
in  size  very  slowly.  In  fifteen  minutes  the  edge  begins  to  open  form- 
ing indentations,  which  gradually  work  their  way  across  the  figure. 
As  they  increase  in  length  these  begin  to  curve,  and  in  three-quarters 
of  an  hour  have  doubled  themselves  two  or  three  times. 
Cod  liver  oil  spreads  in  a  large  film  ;  a  little  way  from  the  edge  a 
row  of  small  holes  appear,  and  in  a  minute  or  two  the  surface  is  covered 
with  them  ;  these  gradually  enlarge,  assuming  irregular  shapes,  soon 
separated  by  branching  lines. 
Cod-liver  oil  with  lard  oil  spreads  very  like  the  former,  but  in  a 
few  moments  the  edge  opens  and  the  film  separates  partly  across,  in 
a  moment  one  of  the  projecting  points  begins  to  curve  itself  towards 
the  centre,  bending  more  and  more  until  it  forms  a  coil.  Meanwhile 
a  few  holes  have  appeared,  which  spread  irregularly,  throwing  out 
projecting  points. 
Castor  oil  spreads  instantly,  the  edge  remaining  entire;  openings 
appear  thickly  in  thirty  seconds  and  increase  gradually,  but  unevenly, 
those  nearer  the  edge  being  larger,  and  lengthening  out  irregularly 
as  they  spread.  The  figure  lasts  some  time.  Castor  with  a  little 
lard  oil  makes  a  smaller  figure,  and  not  nearly  so  much  broken, 
in  five  minutes  the  holes  open  into  each  other  and  the  figure  breaks 
up  from  the  edge. 
A  mixture  of  castor  and  poppy-seed  oils  spreads  to  form  a  lace- 
work  border,  but  smoothes  out  to  an  entire  edge  soon,  and  within  a 
few  seconds  openings  appear.  The  figure  in  size  and  general  appearance 
is  more  like  castor  oil  alone,  but  the  holes  spread  less  uniformly  in  a 
given  time,  a  few  being  larger,  but  the  greater  portion  much  smaller. 
In  fifteen  minutes  there  is  a  general  tendency  to  break  up. 
Castor  with  a  little  croton  oil  throws  out  a  spray,  which  in  a  few 
