ON  EMULSIONS. 
485 
rapidly,  the  liquids  differing  greatly  in  their  density,  but  both 
having  great  mobility.  In  the  two  former  (water  and  spirit)  the 
subsidence  was  much  slower,  and  there  was  no  tendency  to  clot, 
the  liquids  occupying  a  position  between  the  two  former,  as  re- 
gards density,  but  being  inferior  to  them  both  as  regards  mobility. 
The  experiment  was  repeated,  substituting  fine  powdered  char- 
coal for  magnesia.  The  subsidence  was  in  all  cases  slower,  but 
the  relation  before  observed  was  still  maintained.  In  the  water 
and  spirit  subsidence  was  not  more  complete  in  twenty-four  hours 
than  it  was  in  the  chloroform  and  ether  in  as  many  minutes.  The 
charcoal  also  appeared  a  little  clotted  in  the  chloroform.  We 
may  conjecture  that  the  great  mobility  of  chloroform  facilitates 
the  action  of  the  agglomeration  forces,  while  its  density  subtract- 
ing from  the  effect  of  gravitation  allows  them  time  to  manifest 
their  action. 
The  recent  experiments  of  Mr.  Crookes,  showing  how  readily 
mercury  may  be  divided  when  its  surface  is  tarnished  by  sulphuret- 
ted hydrogen,  and  how  readily  it  again  unites  when  sodium  is 
supplied  to  abstract  the  sulphur,  suggests  that  we  should  look  for 
a  film  upon  the  surface  of  the  globules  of  emulsified  oil,  and  that 
materials  which  cause  the  separation  of  the  oil,  may  do  so  in 
virtue  of  a  power  of  dissolving  or  decomposing  this  film. 
In  concluding  these  observations,  let  me  express  a  hope  that 
some  other  members  of  the  Conference  will  add  a  few  notes  to 
my  own.  On  the  list  of  subjects  for  investigation  it  is  stated 
that  I  will  be  glad  to  receive  communications  upon  the  subject. 
I  have  not  received  a  line  from  any  one.  I  cannot  but  think 
that  many  gentlemen  may  have  fragments  of  information  which 
while  isolated  appear  valueless  ;  let  me  assure  all  my  fellow-mem- 
bers that  no  observations  are  too  fragmentary  or  isolated  to  be 
thankfully  received.  To  any  one  engaged  in  an  investigation 
the  most  trifling  matter  is  not  to  be  overlooked,  and  communica- 
tions always  act  as  an  encouragement  and  stimulant  to  continued 
work. 
11,  Grey  Street,  Newcastle-on-Tyne,  July,  1865. 
— London  Pharm.  Jour.  Oct.  1,  1865. 
