122 
Syr  tip  of  Hydr  iodic  Acid. 
/Am.  Jour.  Pharm. 
\      March,  1899. 
ference  universally  given  to  the  present  process  is  in  the  main  due 
to  its  ready  manipulation. 
The  Pharmacopoeia,  in  furnishing  its  working  formulas,  must 
primarily  consider  the  ease  with  which  they  are  manipulated. 
Difficult  processes  are  seldom  if  ever  attempted  by  the  average 
retail  pharmacist,  and  are  as  a  rule  profitable  to  manufacturers. 
Preparations  should  also  be  directed  to  be  made  from  compounds 
easily  obtainable,  in  active  use  and  as  inexpensive  as  possible. 
Chemicals,  which  are  not  used  for  any  purpose  but  as  ingredients 
in  a  preparation,  should  not  be  ordered,  if  they  can  be  replaced  by 
those  more  frequently  employed. 
These  thoughts  occurred  to  the  writer,  while  manipulating  various 
formulas  for  this  preparation. 
Syrup  of  hydriodic  acid,  as  prepared  by  the  official  process,  will 
contain  a  small  quantity  of  potassium  bitartrate. 
The  insignificant  amount  present  is- unobjectionable,  but  with  the 
view  of  avoiding  the  same,  the  writer  prepared  hydriodic  acid  by 
double  decomposition  between  barium  iodide  and  sulphuric  acid, 
but  foreseeing  the  objection  to  the  limited  use  of  the  barium  salt, 
this  process  was  abandoned. 
For  this  and  other  reasons  it  must  be  deemed  advisable  to  retain 
the  present  official  process. 
But  in  several  particulars  it  is  open  to  improvement. 
The  amounts  of  potassium  iodide  and  tartaric  acid  may  first  be 
considered. 
The  Pharmacopoeia  orders  13  grammes  of  the  former  and  12 
grammes  of  the  acid  to  be  used  in  preparing  1,000  grammes  of  the 
syrup. 
These  quantities,  in  the  writer's  experience,  are  insufficient  to 
furnish  a  I  per  cent,  syrup. 
In  an  examination  of  a  number  of  specimens  of  the  syrup,  pre- 
pared strictly  according  to  official  directions,  the  writer  found  the 
same  to  fall  short  of  the  official  requirement,  when  estimated  with 
decinormal  silver  nitrate  V.  S. 
This  is  due  to  the  fact,  that  the  official  quantities  of  potassium 
iodide  and  tartaric  acid  are  calculated  too  close. 
To  demonstrate  this  point,  the  following  calculation,  first  with 
potassium  iodide,  must  be  employed  : 
KI  +  H2QH406  =  HI  +  KHC4H406 
165-56  127-53 
