Am.  Jour.  Piiarip. ) 
Sept.,  1885,  I 
Camphor'  Motions. 
445 
intensity.  The  fact  that  these  motions  could  be  started  by  means  of 
an  electrified  rod  Avas  a  new  one.  Those  who  had  decided  that  camphor 
motions  were  not  due  to  electricity  were  not  acquainted  with  it,  and  I 
was  led  to  believe  by  this  fact,  and  by  others  which  I  gave  at  the  time, 
that  camphor  motions  were  electrical  phenomena.  There  was,  however, 
something  unsatisfactory  in  this  method  of  applying  electricity  to  the 
Avater  on  which  pieces  of  camphor  floated,  but,  at  that  time,  no  other 
method  occurred  to  me.  Afterwards  the  whole  subject  slipped  from  my 
mind,  but,  quite  recently,  the  following  experiment  has  suggested  itself, 
which  seems  to  show  that  camphor  motions  are  not  due  to  the  state  of 
electrical  tension  of  the  liquid  on  which  pieces  of  camphor  float. 
The  experiment  was  performed  in  a  glass  dish  about  two  inches  deep, 
and  of  five  inches  diameter.  This  was  filled  with  water  up  to  within 
an  inch  of  the  top.  The  bottom  of  the  dish  and  the  sides,  up  to  within 
an  inch  of  the  top,  were  covered  in  tin  foil.  A  metallic  wire  dipped 
in  the  water  of  the  dish,  with  one  end  out  of  the  water,  but  having  na 
connections  with  the  outside  lining  of  tin  foil. 
This  glass  dish  was  equivalent  of  a  Leyden  jar,  which  could  be 
charged  with  electricity  from  the  plate  of  an  electrophorus  by  touching 
the  wire  dipping  into  the  water  with  this  plate,  laying  a  finger  at  the 
same  time  on  the  outside  armature. 
A  few  pieces  of  camphor  were  placed  upon  the  water  in  the  dish, 
and  these  were  reduced  to  immobility  by  dipping  a  finger  in  the  water. 
After  this  the  water  in  the  dish  was  charged  with  electricity  by  re- 
peatedly placing  the  plate  of  an  electrophorus  in  contract  with  the  wire 
dipping  into  the  water,  while  the  outside  armature  was  touched  with 
a  finger. 
There  was  no  effect  produced  on  the  pieces  of  camphor  floating  on 
the  water  of  the  dish.  These  remained  motionless,  not  exhibiting  the 
slightest  tremor.  There  could  be  no  doubt  that  the  water  surface  wa& 
in  a  greater  state  of  electrical  tension  in  this  experiment  than  when  the 
water  is  electrified  by  dipping  an  excited  rod  in  it,  for,  by  placing  one 
hand  on  the  outside  armature  of  the  dish,  and  slowly  approaching  the 
water  surface  with  a  finger  of  the  other  hand,  a  perceptible  spark 
was  obtained. 
There  seems  to  be  a  discrepancy  between  the  results  to  be  obtained 
in  these  two  classes  of  experiments. 
By  dipping  an  electrified  rod  successively  in  water  the  camphor 
motions  always  take  place,  while,  when  we  electrify  by  applying  the 
