I2i  Syrup  of  Hydriodic  Acid.  {AmiS;S.raJ- 
A  syrupy  liquid,  containing  about  I  per  cent,  by  weight  of  abso- 
lute hydriodic  acid  (HI,  127-53),  or  about  13  grammes  in  100  c.c. 
Grammes. 
Potassium  iodide,  thirteen  and  one-half  grammes   13*5 
Potassium  hypophosphite,  one  gramme   i" 
Tartaric  acid,  twelve  and  one-half  grammes   12*5 
Sugar,  625  grammes  625* 
Diluted  alcohol  
Water,  of  each  a  sufficient  quantity  to  make  1,000  grammes  .  .  1,000 
Dissolve  the  two  potassium  salts  in  15  c.c.  of  water,  and  the  tar- 
taric acid  in  25  c.c.  of  diluted  alcohol. 
Mix  the  two  solutions  in  a  vial,  shake  it  thoroughly  and  place  it 
in  ice  water  for  half  an  hour,  occasionally  shaking.  Filter  the  mix- 
ture through  a  small,  rapidly-acting  white  filter  into  a  bottle  gradu- 
ated to  75  c.c.  Carefully  allow  the  liquid  to  drain  and  wash  the 
bottle  in  which  the  mixture  was  prepared  and  the  filter  repeatedly 
with  small  portions  of  diluted  alcohol,  allowing  each  portion  to 
drain  separately.  When  the  desired  amount  of  filtrate  is  obtained, 
dilute  it  with  275  c.c.  ot  water,  add  the  sugar  and  dissolve  it  by 
agitation  without  heat.  Finally  add  a  sufficient  quantity  of  water 
to  make  the  product  weigh  1,000  grammes. 
Strain  if  necessary. 
If  it  would  be  deemed  advisable  to  simply  dilute  the  acid  solution 
with  syrup,  such  directions  can  be  substituted  for  the  more  tedious 
method  of  dissolving  the  sugar  by  agitation.  The  specific  gravity 
of  the  syrup,  prepared  by  the  latter  method,  closely  approximates 
that  of  simple  syrup,  about  1-315  to  1-320. 
PRESERVATION. 
The  Pharmacopoeia  gives  no  specific  directions  for  preservation 
of  the  syrup. 
Due  to  this  fact  it  is  often  exposed  to  all  light  and  temperature 
conditions. 
In  a  previous  paper  the  writer  dwelt  upon  the  discoloration 
occurring  in  this  and  other  acid  syrups. 
The  influence  of  summer  heat  was  specifically  mentioned  to  be 
of  material  importance  in  the  production  of  this  change. 
The  Pharmacopoeia  should  give  the  following  directions  for  pre- 
serving the  syrup. 
Syrup  of  hydriodic  acid  should  be  kept  in  well-stoppered  bottles  in 
a  cool  and  dark  place. 
