29  2  Preparation  of  Ethyl- Bromide.       { AmJ^^J7h9arm' 
When  ether  and  chloroform  are  mixed  there  is  an  elevation  of  tem- 
perature, and  the  greatest  heat  is  produced  when  the  mixture  is  made  in 
equi-molecular  proportions.  43  grams  of  ether  at  20°C.  being  mixed 
with  60  grams  of  chloroform  at  the  same  temperature,  the  temperature 
of  the  mixture  rises  to  350.  The  ether  should  be  anhydrous,  other- 
wise the  mixture  will  be  turbid.  There  is  but  little  contraction  in- 
volume,  and  it  may  be  supposed  that  molecular  combination  take& 
place  between  the  ether  and  chloroform. 
The  mixture  may,  however,  be  separated  into  its  constituents  by 
fractional  distillation.  It  begins  to  boil  at  50  to  510,  and  several  fractio- 
nations are  necessary.  When  it  is  allowed  to  evaporate  spontaneously,, 
both  substances  pass  into  vapor  together,  and  the  composition  of 
the  mixture  does  not  sensibly  change.  It  burns  with  a  smoky  .flame,, 
the  chloroform  burning  with  the  ether.  These  facts  seem  to  show 
that  an  unstable  molecular  compound  is  formed,  as  suggested  by  the 
late  Dr.  Atlee,  who  preferred  the  mixture  to  all  other  anaesthetics  in  his- 
practice. 
ON  THE  PREPARATION  OF  ETHYL  BROMIDE. 
By  Wm.  H.  Greene,  M.D. 
As  bromide  of  ethyl  has  recently  attracted  some  notice  as  an  appar- 
ently safe  and  agreeable  anaesthetic,  having  all  of  the  advantages  of 
chloroform  without  producing  the  nauseating  effects  which  render  ether 
unpleasant,  an  easy  process  for  its  preparation  may  be  acceptable  to 
pharmacists,  for  the  compound  is  not  now  in  the  market. 
Most  cheaply  prepared  by  the  action  of  bromine  on  alcohol  in 
presence  of  amorphous  phosphorus  (Personne),  ethyl  bromide  so  made 
possesses  a  slightly  garlicky  odor,  almost  impossible  to  get  rid  of  j  this 
is  possibly  due  to  a  trace  of  ethylphosphine  or  a  phosphinic  ether,  but 
however  this  may  be,  the  product  has  been  objected  to  on  account  of 
the  odor. 
The  process  recommended  by  de  Vrij,  the  action  of  a  mixture  of 
strong  sulphuric  acid  and  alcohol  on  potassium  bromide  yields  a  product 
contaminated  with  ordinary  ether,  and  as  ethyl  bromide  and  ether  boil 
at  400  and  350  respectively,  the  ether  cannot  be  removed.  This  con- 
tamination is  avoided  if  the  sulphuric  acid  be  dilute,  and  the  following, 
process  gives  satisfactory  results  in  the  preparation  not  only  of  ethyl 
bromide  but  of  other  alcoholic  bromides  : 
