164  Preparation  of  Hydrohromic  Acid.       {  ^'"apXSsT"^ 
ON  THE  PREPARATION  OF  HYDROBROMIC  ACID. 
By  Thomas  S.  Wiegand,  Ph.G. 
Bead  at  the  Pharmaceutical  Meeting,  March  20. 
One  of  the  first  things  that  attracts  the  attention  of  the  apothecarv 
in  scanning  the  pages  of  the  United  States  Pharmacopoeia  is  the  elimina- 
tion of  nearly  all  the  processes  for  making  chemicals ;  to  one  brought 
up  to  the  business  under  the  old  regime  it  was  thought  that  the  prepara- 
tion of  everything  directed  by  the  Pharmacopoeia,  excepting  those  arti- 
cles which  required  special  apparatus  or  expensive  outfit,  was  the  pecu- 
liar duty  of  the  pharmacist,  and  in  view  of  this  the  Pharmacopoeia 
Avas  formerly  so  framed,  but  in  our  present  code,  so  many  of  the  for- 
mulas are  omitted  that  their  absence  is  a  noted  peculiarity  and  a  great 
void  is  felt;  it  may  be  said  in  extenuation  of  tliese  omissions  that  they 
can  be  made  cheaper  on  the  large  scale  than  on  the  small  one,  but 
this  does  not  render  the  omission  any  the  less  an  omission,  or  a  felt  want 
more  easily  submitted  to.  To  many  the  Pharmacopoeia  is  a  law,  and  to 
the  law  they  are  in  the  habit  of  looking  for  direction. 
Among  the  formulas  thus  omitted  is  that  for  diluted  hydrobromic 
acid.  The  formula  for  this  preparation  that  has  attracted  most  atten- 
tion lately  is  the  one  published  by  Dr.  E.  R.  Squibb,  which  consists  of 
decomposing  potassium  bromide  with  an  equivalent  portion  of  sul- 
phuric acid,  washing  the  potassium  sulphate  to  remove  the  adhering 
hydrobromic  acid,  and  then  concentrating  and  distilling ;  this  is  all 
quite  possible,  but  so  tedious  and  so  likely  to  fracture  the  glass  retorts 
from  the  "  bumping,'^  that  it  is  quite  unsatisfactory.  The  facility  with 
which  this  article  can  be  prepared  by  passing  hydrogen  sulphide  into  a 
mixture  of  bromine  and  water  is  such  that  no  pharmacist  need  be  at  a 
loss  to  prepare  it  by  the  following  process  : 
Having  a  flask  fitted  with  a  cork,  which  is  perforated  to  receive  a 
tube  reaching  just  below  the  cork  and  rendered  tight  by  waxing  it,, 
connect  it  by  means  of  a  piece  of  gum  tubing  with  another  tube  bent 
at  right  angles ;  let  the  lower  end  of  this  tube  dip  to  the  bottom  of  a 
vessel  which  is  shaped  like  a  glass  percolator,  and,  in  fact,  a  glass  per- 
colator is  the  best  for  the  purpose,  and  this  is  closed  at  the  bottom 
with  a  rubber  stopper  and  fitted  with  a  close-fitting  cap,  through  which 
the  bent  tube  passes,  and  also  another  to  prevent  the  gas  from  blowing 
off  the  cap.    When  these  arrangements  are  made,  a  quantity  of  sul- 
