A flSpSft  SK?"'}      ^e  Cohesion-Figures  of  Oils,  etc.  407 
the  whole  surface  of  the  film,  there  seems  to  be  a  contest  between  the 
cohesion  of  the  oil  particles  and  the  adhesion  between  them  and  the 
water.  The  oil  makes  repeated  efforts  to  gather  itself  closer  together, 
when  the  water  instantly  reacts,  giving  a  wavy  appearance  to  the 
whole  figure.  The  play  of  colors  at  this  point  is  beautiful  and  serves 
to  bring  out  the  lines  more  perfectly.  In  a  few  seconds  innumerable 
little  holes  appear  over  the  surface,  which  soon  are  separated  only  by 
threaded  lines,  and  the  figure  is  like  the  most  exquisitely  fine  lace. 
Oil  of  cinnamon  forms  a  figure  not  more  than  half  the  size  of  the 
last  named.  In  a  few  seconds  small  portions  are  detached,  and 
shortly  separates  into  distinct  drops,  four  or  five  larger  and  a  number 
of  smaller  ones,  scattered  about.  With  mixtures  in  different  propor- 
tions of  oil  of  turpentine,  the  figures  formed  differently,  taking  more 
the  characteristics  of  the  adulterant  as  it  predominated. 
Oil  of  nutmeg  forms  a  large  figure  instantly,  the  edge  showing  a 
beaded  line.  It  gathers  itself  together  and  spreads  again,  very  like 
oil  of  turpentine,  but  the  surface  presents  more  the  appearance  of 
watered  silk.  Within  60  seconds  some  holes  appear,  and  in  80  more 
the  surface  is  covered  with  them  ;  these  scarcely  spread  to  more  than 
a  sixteenth  of  an  inch  in  diameter,  but  from  the  first  each  is  bordered 
with  a  dotted  edge.  The  figure  lasts  some  time  without  changing 
materially,  except  the  openings  lengthen  out  into  an  oblong  shape, 
remaining  entirely  distinct.  The  play  of  colors  is  very  fine.  With 
the  addition  of  one- third  the  volume  of  oil  of  turpentine,  the  first 
spreading  is  little  different,  but  openings  appear  in  half  the  time  and 
the  dotted  border  does  not  come  as  soon  ;  in  about  four  minutes  the 
figure  is  most  characteristically  marked,  and  soon  breaks  up  entirely, 
this  being  the  distinctive  difference  between  the  pure  oil  and  the 
mixture. 
Oil  of  peppermint  spreads  instantly  to  a  large  figure,  and  in  ten 
or  fifteen  seconds  openings  appear,  which  increase  rapidly  in  size; 
at  first  they  look  some  like  the  last  named,  but  are  not  nearly  so  nu- 
merous, and  the  border  soon  is  more  like  tiny  drops.  In  one  and  a 
half  or  two  minutes  they  begin  to  run  together  and  the  figure  breaks 
up.  With  the  addition  of  turpentine  oil  the  figure  forms  more 
filowly,  and  the  breaking  up  is  less  rapid,  but  in  five  minutes  the  out- 
lines only  remain. 
Oil  of  bergamot  spreads  instantly,  in  30  seconds  tiny  openings  appear, 
not  very  abundant,  and  increase  in  size  slowly  ;  in  five  minutes  they 
