Am.  jour.  Pharm. i      Churchill's  Tincture  of  Iodine. 
January.  19 19.    3  1 
41 
The  modus  operandi  given  is  as  follows  :  Dissolve  the  potassium 
iodide  in  water,  then  add  the  iodine  and  600  milliliters  of  alcohol, 
and  when  all  the  iodine  is  dissolved  add  sufficient  alcohol  to  make  the 
product  measure  1,000  milliliters. 
It  will  be  noticed  that  in  all  these  formulas  the  ratio  between 
the  iodine  and  potassium  iodide  is  five  to  one.  There  is  five  times 
as  much  iodine  as  potassium  iodide.  This  is  a  larger  proportion 
of  iodine  as  compared  with  potassium  iodide  than  found  in  any 
other  tincture  containing  both  ingredients. 
Criticisms. 
Criticisms  have  been  made  that  the  present  formula  is  not  satis- 
factory. All  the  iodine  does  not  seem  to  be  in  solution  and  particles 
of  it  can  be  noticed  in  the  bottom  of  the  container.  The  fault  must 
be  that  there  is  not  enough  potassium  iodide  to  help  to  dissolve  all 
the  iodine. 
Experiments. 
I  have,  therefore,  based  my  experiments  which  are  the  original 
work  in  my  thesis  upon  the  three  following  questions : 
1.  How  much  iodine  is  dissolved  in  the  present  formula? 
2.  How  much  potassium  iodide  is  needed  to  dissolve  the  official 
amount,  16.5  per  cent,  of  iodine? 
3.  "What  other  changes  could  be  employed  to  make  a  satisfactory 
tincture  ? 
All  tinctures  used  in  the  experiments  were  made  by  the  author 
in  the  Pharmaceutical  Laboratory  of  the  Philadelphia  College  of 
Pharmacy  and  were  kept  for  various  lengths  of  time  before  the 
determinations  were  made.  One  hundred  mils  of  tincture  were 
made  in  each  case,  as  that  was  considered  a  fair  sample.  The  tinc- 
tures were  prepared  according  to  the  N.  F.  IV  formula. 
The  assay  for  iodine  consisted  of  the  following  procedure,  which 
was  carefully  followed  through  all  the  experiments.  "  Mix  5  mils 
of  the  tincture  with  25  mils  of  water  and  titrate  with  Tenth-Xormal 
Sodium  Thiosulphate  Volumetric  Solution.  Each  mil  of  Tenth- 
Xormal  Sodium  Thiosulphate  YS  equals  0.01692  Gm.  of  Iodine, 
the  factor  in  U.  S.  P.  IX."  As  the  sodium  thiosulphate  was  not 
strictly  tenth-normal  the  factor  for  it  was  obtained  each  day  before 
it  was  used  for  a  titration. 
The  assays  were  made  in  the  Chemical  Laboratory  of  the  Phila- 
