242  Ethyl  Bromide.  {""^fcf^S"'- 
followed  out  by  Dr.  Greene,  biat  which  never  served  me,  in  the  pro- 
portions mentioned,  to  obtain  any  appreciable  quantity  of  the  ethyl 
bromide.  • 
Its  chemical  composition  was  early  determined  to  be  C2H5Br,  its 
specific  gravity  i"40,  and  its  boiling  point  io6°F. ;  it  will  not  burn,  and 
its  vapors  even  will  extinguish  flame. 
Finding  considerable  objection  to.  the  product  of  the  earlier  process 
on  account  of  its  alliaceous  odor,  probably  due  to  free  phosphorus  or 
an  ethyl  phosphide,  I  was  soon  led  to  produce  it  by  De  Vrij's  method, 
which,  however,  I  found  deficient  in  the  amount  of  sulphuric  acid,  and 
It  was  not  until  I  had  almost  trebled  its  quantity  that  I  succeeded  in 
completely  converting  the  entire  amount  of  alcohol  into  ethyl  bromide. 
The  process  I  employed  and,  after  various  experiments  and  modifi- 
cations found  to  answer  best,  is  as  follows  : 
24  ounces  of  potassic  bromide,  coarsely  powdered,  are  added  to  a 
mixture  of  64  ounces  of  sulphuric  acid  and  32  ounces  of  water.  After 
the  mixture  has  sufficiently  cooled,  16  fluidounces  of  alcohol  (95  per 
cent.)  are  added  thereto,  the  whole  placed  in  a  large  flask  contained 
in  a  sand-bath  and  connected  with  a  Liebig's  condenser,  heat  applied 
sufficiently  that  the  contents  of  the  flask  should  be  at  about  200°F., 
and  there  to  be  maintained  until  the  reaction,  which  will  go  on  quite 
lively  for  a  while,  shall  have  ceased,  and  the  ethyl,  which  has  rapidly 
been  gathering  in  a  receiver  containing  about  one  ounce  of  water,  has 
ceased  to  come  over,  as  can  easily  be  detected  when  it  fails  to  further 
sink  to  the  under  surface  of  the  layer  of  water.  The  ethyl  bromide  so 
obtained  will  amount  to  about  20  ounces,  and  should  be  shaken  with  a 
solution  of  potassic  bicarbonate,  subsequently  washed  with  water  and 
purified  by  redistillation,  as  described  below. 
The  chemistry  of  this  proces  is  quite  plain,  the  sulphuric  acid  form- 
ing acid  potassium  sulphate,  the  bromine  taking  the  place  of  the  oxygen 
in  the  ethyl  oxide,  forming  water  with  the  hydrogen  present,  which 
expressed  in  symbols  would  read  as  follows  : 
KBr  +  H^SO.H-aHgO^KHSO^+H^O  +  C^HgBr. 
The  operation  is  in  itself  so  simple,  so  rapid  and  so  totally  devoid  of  all 
danger,  that  its  advantages  over  the  earlier  ones  are  readily  obvious. 
It  can  easily  be  conducted  on  the  laboratory  table  of  most  any  phar- 
macy, and  will  yield  a  product  which  possesses  all  the  characteristics 
as  described  above.  Its  cost  is  an  item  of  the  greatest  importance  to 
the  pharmacist,  in  view  of  the  very  high  price*asked  for  it  at  one  time, 
