342 
On  Monobromated  Camphor. 
J  Am.  Jour.  Pharm. 
\     Aug.  1, 1872. 
larger  than  by  Perkin's  process,  and  the  entire  absence  of  all  danger 
by  the  bursting  of  apparatus  recommends  this  method  as  more  prac- 
tical than  that  of  Swarts.  Although  more  time  is  required  for  finish- 
ing the  process  completely,  the  different  reactions  will  not  require 
much  supervision,  except  the  careful  attention  to  the  temperatures. 
The  combining  weight  of  camphor  C20  H16  02  is  152 ;  that  of  2  Br 
=160;  equal  weights  of  the  two  substances,  therefore,  give  a  slight 
excess  of  camphor.  I  have  found  it  advisable  to  use  about  one-twelfth 
more  of  camphor,  the  excess  of  which  remains  in  the  mother  liquor, 
and  very  likely  serves  to  prevent  the  formation  of  bibromated  cam- 
phor (C20  H14  Br2  02,)  if  the  oily  residue  previous  to  its  final  treatment 
has  liberated  bromine  on  exposure  to  the  light.  A  greater  increase 
of  camphor  is  unnecessary,  since  even  in  the  proportion  of  two  to  one 
bromine,  the  formation  of  the  oily  compound  and  the  liberation  of 
bromine  on  subsequent  exposure  is  not  prevented,  while  the  difficulty 
to  obtain  the  substitution  compound  free  from  camphor  is  considerably 
increased. 
In  regard  to  the  quantity  that  may  be  conveniently  worked  up  at  a 
time,  the  manipulation  described  below  renders  it  possible  to  use  12 
oz.  of  bromine  in  a  retort  of  the  capacity  of  a  quart,  in  which  even  14 
oz.  have  been  operated  upon  by  me  at  once. 
Regarding  the  necessary  apparatus,  I  have  found  the  following  most 
serviceable,  and  well  adapted  for  the  purpose. 
A  quart  retort  is  placed  in  such  a  position  that,  the  neck  being  suf- 
ficiently raised,  any  liquid  condensing  therein  may  readily  flow  back 
into  the  retort.  To  the  neck  is  joined  a  glass  tube,  eighteen  inches 
to  two  feet  in  length,  bent  downwards  at  the  farther  end,  and  by 
means  of  India  rubber  and  glass  tubing  connected  with  a  bottle  of 
about  8  oz.  or  more  capacity  ;  the  glass  tube  is  cut  off  immediately 
beneath  the  cork,  while  another  glass  tube,  running  nearly  to  the  bot- 
tom of  the  bottle,  is  bent  twice  at  right  angles,  and  dips  with  the  other 
end  into  an  open  bottle  containing  about  8  oz.  of  water  and  an  alkali 
for  the  absorption  of  the  hydrobromic  acid.  The  intervenient  bottle, 
which  is  empty,  serves  merely  as  a  receptacle  for  the  bromide  solution, 
which  is  drawn  over  on  the  cooling  of  the  contents  of  the  retort,  and 
pressed  back  again  into  the  last  bottle  on  the  reapplication  of  heat; 
the  liquid  is  thereby  prevented  from  running  into  the  retort,  but  the 
bottle  may  be  replaced  by  a  Welter's  safety-tube  inserted  into  the 
tubulure.    Since,  theoretically,  one  half  of  the  bromine  employed  is 
