CHROMIC  ACID  AND  THE  VOLATILE  OILS. 
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bebs,  and  to  a  number  of  oxygenous  oils,  did  not  tend  to  corrobo- 
rate the  impression. 
The  oil  of  lemon  was  very  active,  and  so  powerful  as  to  cause 
the  repulsion  of  comparatively  large  masses  of  tmdecomposed 
chromate  of  potassa  in  the  acid  mixture,  at  the  distance  of  one 
inch  or  more. 
The  oil  of  orange  (the  genuineness  of  which,  however,  I  had 
some  reason  to  question)  was  also  very  energetic  ;  and,  in  addi- 
tion, I  observed  under  a  moderate  magnifier,  a  phenomenon  un- 
noticed in  the  cases  of  the  other  oils.  It  consisted  in  an  inimita- 
ble crumpling  of  the  acid  liquid  next  the  oil,  in  parallel  lines  at 
right  angles  with  the  margin  of  the  oil ;  the  whole  outline  pre- 
senting a  double  convexity,  like  the  edge-view  of  a  double  con- 
vex lens.  The  beautiful  crumplings  came  and  went  like  the  cor- 
ruscations  of  the  boreal  aurora. 
The  repulsive  power  of  the  oil  of  cubebs  was  far  less  apparent 
than  that  of  the  oils  just  named,  but  the  decomposing  agency 
was  very  striking  though  slow  in  its  action. 
Oil  of  turpentine  produced  a  moderate  motion  in  the  acid 
mixture,  and  finally  darkened  the  color  of  it  till  it  became 
almost  black;  but  on  diluting  it  the  color  became  green. 
The  oils  of  origanum,  of  chenopodium  and  of  gaultheria,  (oxy- 
genous oils,)  occasioned  more  or  less  motion  and  discoloration  in 
the  acid  mixture. 
When  the  concave  glasses  containing  the  respective  liquids  were 
placed  within  a  small  fraction  of  an  inch  apart,  with  but  a  few 
drops  of  the  liquid  in  them,  and  the  chromate  was  in  small  blocks 
lying  in  the  acid,  a  retreating  action  commenced  in  the  acid  mix- 
ture at  the  edge  next  the  oil,  by  which  the  whole  mass  was  driven 
along  like  water  before  wind.  And  what  made  it  still  more 
curious  wras  that  this  action  was  not  continuous,  but  intermittent ; 
an  interval  of  several  seconds  transpiring  between  the  motions. 
While  witnessing  the  rolling  over  of  the  blocks  of  chromate,  all 
in  one  direction  and  simultaneously,  with  suitable  respites,  I 
could  hardly  forebear  fancying  the  existence  of  a  little  army  of 
invisible  Lilliputians  adjusting  their  shoulders  to  the  tiny  rocks, 
and  heaving  them  onward  with  simultaneous  efforts,  at  the  pro- 
per signal. 
Whatever  the  agency  was,  it  is  certain  that  the  whole  mass, 
