14 
ME.  GASSIOT  ON  THE  STEATIEICATIONS  AND  DAEK  BAND  IN 
positive  and  the  mercury  negative,  the  tube  was  filled  with  brilliantly  illuminated 
phosphorescent  light.  If,  under  this  condition,  a powerful  magnet  was  presented  to 
the  light,  the  stratifications  were  drawn  over  and  from  the  upper  ball,  while  a minute 
spot  of  liquid  mercury  suspended  from  it  was  attracted  and  repelled  according  to  the 
polarity  of  the  magnet. 
48.  In  this  experiment  I noticed  another  effect  which  I have  not  seen  in  any  of  my 
other  apparatus.  The  magnet  so  divided  the  electrical  discharge,  that  the  rays  producing 
the  fluorescence  in  the  glass  tube  were  all  accumulated  in  the  neighbourhood  of  the  nega- 
tive terminal,  the  glass  in  that  part  being  highly  fluorescent,  while  the  positive  portion 
exhibited  little  or  no  signs  of  this  phenomenon. 
49.  I refrain  for  the  present  from  offering  any  observations  as  to  the  action  of  the 
magnet  on  the  discharge.  The  intimate  relation  of  magnetic  and  electric  action  has  long 
since  been  shown ; but  the  curious  effect  of  the  power  of  a magnet  to  draw  out  the  stra- 
tification from  the  positive  terminal  (47.),  and  in  some  instances  its  poweidul  action 
on  that  portion  of  the  discharge  which  exhibited  the  phosphorescent  hght  in  its  greatest 
intensity  (48.),  are  worthy  of  further  examination.  In  the  preceding . eocperinnents  my 
object  was  entirely  directed  to  the  examination  of  the  stratified  and  the  dark  band  dis- 
charge ; at  present  I am  inclined  to  the  opinion  that  the  stratifications  in  the  positive, 
and  the  dark  broad  band  between  it  and  the  negative  glow,  although  apparently  similar, 
are  effects  arising  from  distinct  causes — the  former  from  pulsations  or  impulses  of  a 
force  acting  on  highly  attenuated  but  a resisting  medium,  the  latter  from  interference. 
I am  at  this  time  engaged  in  making  further  experiments  for  the  elucidation  of  this 
novel  and  remarkable  phenomenon. 
John  P.  Gassiot. 
Clapham  Common, 
5 January,  1858. 
NOTE. — Eeceived  March  3, — Eead  March  4,  1858. 
50.  Shortly  after  presenting  the  preceding  account  of  my  experiments  to  the  Royal 
Society,  I had  the  pleasure  of  being  introduced  to  Dr.  Esselbach  of  Bonn,  who 
informed  me  that  M.  Geisslee  of  that  city  had  recently  constructed  some  vacuum  tubes 
of  great  delicacy,  and  that  an  account  of  his  experiments  with  Ruhmkoepf’s  inductive 
apparatus  had  been  published  in  Germany.  Through  the  kindness  of  Dr.  Bence  Jones 
I have  since  procured  several  of  the  tubes  from  M.  Geisslee  ; their  forms  are  varied,  and 
show  great  skill  in  the  construction,  the  stratifications  fi'om  the  inductive  discharge 
being  thus  exhibited  in  a most  beautiful  and  striking  manner ; but  the  complexity  in 
the  form  of  the  apparatus  renders  these  tubes  to  a great  extent  unsuitable  for  the 
careful  examination  of  the  phenomena.  I have  not  as  yet  seen  any  publication  of 
M=  Geisslee’s  experiments,  but  I presume  the  tubes  must  have  been  constructed  for  a 
different  object  from  what  I have  been  pursuing,  and  for  which  I purposely  had  mine 
made  in  the  most  simple  form  I could  devise. 
