Am.  Jour.  Pharm.  \ 
March,  1899.  / 
Syrup  of  Hydr iodic  Acid. 
125 
as  supposed,  the  writer  having  found  in  one  instance  that  over  150 
€.c.  of  diluted  alcohol  were  required  in  preparing  1,000  grammes 
of  the  syrup,  until  application  of  starch  paste  and  chlorine  water 
showed  its  complete  removal. 
If  the  present  quantities  and  directions  are  to  be  retained,  this 
reaction  should  be  substituted  for  the  silver  nitrate  test,  as  being 
more  delicate  and  a  better  identity  test. 
Potassium  bitartrate  is  slightly  soluble  in  diluted  alcohol  and  also 
precipitates  silver  nitrate  T.  S. 
Should  this  direction  be  retained,  the  reading  should  be  as  fol- 
lows :  Until  a  drop  or  two,  allowed  to  fall  into  silver  nitrate  T.  S., 
produces  but  a  slight  precipitate,  almost  completely  soluble  on  the 
addition  of  nitric  acid. 
Acting  on  the  necessity  of  an  increase  in  the  quantities  of  potas- 
sium iodide  and  tartaric  acid,  a  number  of  trials  were  made. 
If  the  iodide  is  increased  to  13-5  grammes  and  the  acid  to  12-5 
grammes,  the  latter,  however,  being  still  insufficient  to  decompose 
all  the  hypophosphite  with  formation  of  the  corresponding  acid,  a 
syrup  can  be  prepared  which  contains  I  per  cent,  or  over  of  hydri- 
odic  acid. 
The  washing  of  the  precipitated  potassium  bitartrate  until  the 
acid  is  completely  removed  will  be  unnecessary,  filtration  to  a  defi- 
nite volume  removing  a  sufficient  quantity  to  fulfill  the  official  re- 
quirement. 
Evaporation  of  the  filtrate  can  also  be  dispensed  with,  the  small 
percentage  of  alcohol  not  interfering  with  the  stability  of  the  syrup. 
The  syrup  of  the  Pharmacopoeia  of  1880  contained  8  per  cent, 
of  alcohol,  and  the  presence  of  less  than  4  per  cent,  ought  not  be 
objectionable. 
If  evaporation  of  the  hydriodic  acid  filtrate  is  avoided,  the  sug- 
gestion to  dissolve  the  sugar  directly  in  the  properly  diluted  acid 
solution  may  perhaps  be  considered. 
The  increase  in  time  necessary  for  solution  will  outweigh  the 
trouble  and  loss  occasioned  by  the  present  process  of  evaporation 
to  a  definite  weight. 
The  following  formula,  based  on  the  experiments  described,  has 
been  found  to  yield  a  satisfactory  syrup,  answering  to  the  official 
requirements : 
Syrupus  Acidi  Hydriodici, 
Syrup  of  hydriodic  acid. 
