6o8 
Abstracts  from  Theses. 
( Am.  Jour.  Pharm. 
\  November,  1896. 
ABSTRACTS  FROM  THESES. 
Contribution  from  the  Chemical  Laboratory  of  the  Philadelphia  College  of 
Pharmacy.    No.  160. 
ESTIMATION  OF  AMMONIUM  CHLORIDE  IN  TABLETS. 
Albert  B.  Johnson,  Ph.G.y  made  experiments  with  the  view  of 
devising  a  process  for  the  estimation  of  ammonium  chloride  in  the 
compressed  tablets  of  this  substance,  and  such  organic  matters  as 
licorice,  etc.  The  following  processes  were  found  to  give  practically 
concordant  results.  For  the  ammonia :  powder  a  few  of  the  tablets, 
weigh  a  portion  of  the  powder  :  place  it  in  a  flask,  add  water ;  make 
the  mixture  alkaline  with  sodium  or  potassium  hydrate  solution ; 
connect  the  flask  with  a  condenser  provided  with  a  receiving  flask 
containing  a  measured  volume  of  decinormal  oxalic  acid  volumetric 
solution  to  absorb  the  ammonia,  and  distil  until  two-thirds  of  the 
volume  in  the  first  flask  has  passed  over.  Then  titrate  the  excess 
of  acid  in  the  receiving  flask  with  decinormal  potassium  hydrate 
volumetric  solution,  using  rosalic  acid  as  indicator.  Calculate  the 
amount  of  ammonia  found  into  ammonium  chloride,  and  this  by 
proportion  to  the  weight  of  powdered  tablets  taken  into  percent- 
age. For  the  chlorine :  take  another  weighed  portion  of  the  pow- 
dered tablets,  mix  it  well  in  a  mortar  or  other  vessel,  with  four  or 
five  times  its  bulk  of  chlorine-free  calcium  carbonate,  introduce  the 
mixture  into  a  tube  of  hard  glass,  closed  at  one  end,  and  previously 
charged  with  a  layer  of  unmixed  calcium  carbonate ;  rinse  the  mix- 
ing vessel  with  several  small  portions  of  carbonate,  transferring  each 
in  succession  to  the  tube,  and  follow  these  with  a  layer  of  plain  car- 
bonate. Heat  the  tube  to  low  redness  by  means  of  a  Bunsen 
burner  (or  combustion  furnace),  beginning  at  the  end  of  the  charge 
next  the  open  end,  and  gradually  extending  the  heat  toward  the 
closed  end  until  all  the  carbonaceous  matter  is  consumed,  which  is 
indicated  by  the  disappearance  of  charred  matter.  Allow  the 
tube  to  cool  somewhat,  then  break  it  by  carefully  blowing  on  it  a 
a  few  drops  of  water  from  wash  bottle  ;  add  water  to  the  broken 
mass,  then  nitric  acid  until  effervescence  ceases,  warm  gently,  filter 
to  remove  fragments  of  glass,  and  completely  precipitate  the  filtrate 
with  silver  nitrate,  boiling  to  coagulate  the  precipitate.  Collect  the 
precipitate  on  balanced  filters,  wash  and  dry  at  1300  C.  to  a  con- 
stant weight.    Calculate  the  silver  chloride  into  ammonium  chlor- 
