286 
PREPARATION  OP  LIQUOR  BISMUTHI. 
fraudulently  adulterated  all  become  colored,  either  red  or  brown, 
in  presence  of  this  acid. 
To  test  the  essence  introduce  five  drops  of  it,  with  fifty  drops  of 
concentrated  and  colorless  sulphuric  acid,  into  a  small  tube,  and 
then  shake  them  together.  The  coloration  will  soon  become  ap- 
parent if  the  essence  be  adulterated. 
Rectified  petroleum  forms  the  exception,  as  sulphuric  acid  does 
not  color  it,  but  its  presence  is  betrayed  by  its  insolubility  in  this 
acid.  This  may  be  proved  by  operating  on  twenty  drops  of  es- 
sential oil ;  the  essence  of  mustard  .dissolves,  while  the  petroleum 
floats  in  the  form  of  a  limpid  oil. — Lond.  Ohem.  News,  March 
21,  1865. 
PREPARATION  OF  LIQUOR  BISMUTHI. 
To  the  Editor  of  the  Pharmaceutical  Journal : 
Sir, — The  process  for  the  preparation  of  "  Liquor  Bismuthi," 
which  has  appeared  this  month  in  your  Journal,  and  which  came 
under  my  notice  some  little  time  ago  in  the  pages  of  the 
"  Chemical  News,"  is  similar  in  many  important  points  to  one 
which  I  have  used  successfully  for  more  than  a  year  ;  the  latter 
resulted  from  a  series  of  experiments  suggested  by  the  process 
of  Mr.  Tichbourne,  which  I,  like  Mr.  Gray  Bartlett,  found 
impracticable. 
Upon  the  appearance  of  the  communication  of  the  last-named 
gentleman,  in  the  "  Chemical  News,"  I  tested  the  method  there 
given.  The  results  in  my  hands  were  ,  not  satisfactory,  the 
quantity  of  precipitate  formed  being  scanty  in  proportion  to  the 
weight  of  bismuth  used,  and  a  considerable  portion  proving 
quite  insoluble  in  ammonia.  I  must  acknowledge,  however,  my 
great  obligations  to  that  paper,  from  which  I  have  largely 
drawn,  since  its  appearance,  for  my  own  process ;  the  propor- 
tions there  given  being  almost  universally  adopted,  as  well  as 
certain  points  of  manipulation,  which  will  be  duly  mentioned  in 
the  account  to  be  given  below.  I  have  thus  been  enabled  to 
attain  for  it  a  certainty  and  accuracy  in  which  it  was  previously 
somewhat  wanting,  and  which  will,  I  hope,  recommend  it  to  such 
operative  chemists  as  will  give  it  a  fair  trial. 
I  had  intended  to  reserve  the  following  account  for  a  paper, 
which  I  hoped  to  read  before  the  Pharmaceutical  Conference  at 
