Aj4nu°aury         )      Churchill's  Tincture  of  Iodine. 
43 
The  next  experiments  were  made  with  a  tincture  containing  3.9 
per  cent,  potassium  iodide  and  this  was  found  to  dissolve  all  the 
iodine  at  once,  as  proven  by  titration  immediately  after  preparation. 
Result. — This  led  to  a  conclusion  that  the  proper  amount  of 
potassium  iodide  to  be  added  to  the  present  N.  F.  tincture  is  between 
5  to  6  Gm.  per  1,000  mils. 
Tinctures  were  then  made  containing  3.83  per  cent.,  3.85  per 
cent.,  3.87  per  cent,  potassium  iodide.  The  tinctures  containing  the 
3.87  per  cent,  and  3.85  per  cent,  of  KI  contained  the  required  16.5 
per  cent,  of  iodide  in  solution  right  after  making,  while  the  3.83 
per  cent,  tincture  showed  it  in  three  days. 
Proposed  Improved  Formulas. 
This  brought  me  to  a  conclusion  that  a  tincture  with  either  of 
the  following  two  formulas  could  be  used  with  better  results  than 
the  present  preparation  of  the  National  Formulary. 
Formula  No.  i. 
Iodine   16.5  Gm. 
Potassium  iodide   ;   3.85  Gm. 
Water    25  mils. 
Alcohol,  to  make    100  mils. 
Formula  No.  2. 
Iodine    16.5  Gm. 
Potassium  iodide   3.83  Gm. 
Water    25  mils. 
Alcohol,  to  make    100  mils. 
If  the  tincture  is  to  be  used  right  after  dispensing,  it  is  best  to 
use  the  3.85  per  cent,  potassium  iodide,  but  if  it  is  to  be  put  away  on 
the  shelf  until  needed,  as  is  the  case  in  most  drug  stores,  3.83  per 
cent.,  potassium  iodide  will  be  sufficient. 
Another  Modification. 
The  author  also  made  further  experiments  with  various  tinctures 
by  eliminating  part  of  the  water  and  substituting  alcohol  for  it. 
First  a  tincture  was  made  containing  the  N.  F.  amount  of  potassium 
iodide  made  into  a  saturated  solution  and  alcohol  replacing  the  water 
which  had  been  taken  away.  It  was  found  that  15.24  per  cent,  of 
iodine  was  dissolved  right  after  making  and  that  in  a  tincture  pre- 
