NOTES  ON  LIQUOR  BISMUTHI. 
141 
the  iron  salt  is  oxidized,  nitric  acid  must  be  added  in  small  por- 
tionst  until  the  completion  of  the  process.  Proceeding  in  this 
manner  the  same  result  is  obtained  as  required  by  the  Pharma- 
copoeia, the  danger  of  frothing  is  avoided  and  a  permanent  tinc- 
ture is  obtained. 
Dilute  Hydrocyanic  Acid.  It  is  well  known  that  when  this 
acid  is  not  carefully  secluded  from  light  it  is  rapidly  decomposed 
and  deposits  a  black  substance  (Paracyanogen).  Wittstein,  in- 
his  formula  for  this  acid,  recommends  the  use  of  alcohol  as  a 
preservative,  and  I  wish  to  state  that  I  have  prepared  an  acid 
according  to  this  formula  which  has  kept  without  any  apparent 
change  for  four  months,  although  freely  exposed  to  the  light 
during  that  entire  period.    His  formula  is  as  follows  : 
Dissolve  4  oz.  ferrocyanide  of  potassium  in  16  oz.  of  distilled 
water,  to  which  add  a  cold  mixture  of  3  oz.  sulphuric  acid  and 
12  oz.  alcohol,  sp.  gr.  -840.  Allow  the  mixture  to  stand  for  twenty- 
four  hours,  shaking  it  occasionally.  Separate  the  crystalline 
deposit  by  means  of  a  strainer  and  introduce  the  clear  liquid 
into  a  retort,  the  bottom  of  which  is  covered  to  the  depth  of  one 
inch  with  clean  quartz  sand.  Distil  off  20  fl.  oz.  and  reduce 
the  distillate  to  the  proper  strength  by  the  appropriate  tests. 
The  object  of  using  sand  in  the  retort  is  to  prevent  the  thump- 
ing, which  is  always  a  source  of  great  trouble  during  the  latter 
part  of  the' distillation. — Proceed.  Amer.  Pharm.  Assoc. }  1866. 
NOTES  ON"  LIQUOR  BISMUTHI. 
Br  George  P.  H.  Markoe. 
Much  has  been  written  on  the  preparation  of  Liquor  Bismuthi 
both  in  this  country  and  in  England,  where  it  was  introduced  by 
Mr.  Schacht.  Mr.  R.  C.  Tichborne  was  the  first  to  make  known 
the  composition  of  the  solution,  in  an  able  paper  to  the  London 
Pharmaceutical  Society,  in  which  he  proved  the  bismuth  to  be 
present  iri  the  form  of  an  ammonio-citrate. 
Mr.  N.  Gray  Bartlett,  in  a  paper  published  in  the  Jan.,  1865, 
number  of  the  Am.  Journal  of  Pharmacy,  gave  an  excellent 
working  process  for  the  making  of  citrate  of  bismuth  and  ammo- 
nia in  scales,  and  also  in  solution. 
