226  The  Pharmaceutical  Chemist.       /Am  jour.  Pharm. 
«•       April,  1919. 
bined  with  the  glass,  forming  a  ring  of  arsenical  glass,  which  is 
entirely  different  in  coefficient  of  expansion  from  the  remainder  of 
the  ampoule  and  very  brittle,  hence  comparatively  slight  changes  in 
temperature  frequently  caused  the  tip  to  snap  oft.  On  putting  into 
effect  means  for  carefully  washing  out  the  tip  of  the  ampoule  with 
distilled  water  before  sealing,  the  trouble  disappeared. 
Again,  in  the  manufacture  of  antiseptic  tablets  containing  cor- 
rosive sublimate,  some  suitable  diluent  is  used  that  will  be  com- 
pletely soluble  in  water  and  if  possible  aid  in  the  solution  of  the 
mercuric  chloride  without  reacting  with  it  chemically;  for  this  pur- 
pose ammonium  chloride  or  citric  acid  is  commonly  used.  In  some 
few  instances  both  together  have  been  employed.  To  prevent  the 
material  sticking  to  the  dies  on  a  tablet  machine,  some  lubricant  is 
necessary,  and  as  a  comparatively  soluble  substance,  antiseptic  in 
itself,  boric  acid  is  often  employed  in  a  case  of  this  kind.  A 
quantity  of  tablets  began  to  evolve  considerable  amounts  of  hydro- 
chloric acid  gas,  sufficient  to  rapidly  attack  tinned-iron  containers 
shortly  after  they  were  made.  It  was  found  that  the  boric  acid  used 
as  a  lubricant,  in  the  presence  of  citric  acid,  reacted  upon  the  am- 
monium chloride  with  the  evolution  of  hydrochloric  acid.  The 
omission  of  either  the  boric  or  citric  acid  immediately  remedied  the 
trouble. 
Another  problem  that  seemed  on  the  face  of  it  so  simple  that 
it  was  really  no  problem  at  all  was  the  obtaining  of  material  such 
as  sodium  chloride,  milk  sugar,  and  alkaloidal  salts  of  such  purity 
that  they  would  give  a  solution  in  distilled  water  completely  free 
from  insoluble  floating  particles.  I  would  not  go  so  far  as  to  say 
that  it  cannot  be  done ;  I  think  that  conditions  are  conceivable  under 
which  it  might  be  accomplished;  but  I  have  never  seen  it  done, 
and  upon  a  commercial  scale  it  has,  so  far  as  I  know,  never  been 
accomplished.  You  must  remember,  of  course,  that  the  floating 
particles  thus  referred  to  are  minute,  though  easily  visible  to  the 
naked  eye.  Some  years  ago  it  was  desired  to  prepare  CP.  sodium 
chloride  in  crystalline  form  suitable  for  redissolving  in  distilled 
water  for  intravenous  injection.  No  sodium  chloride  of  sufficient 
purity  was  obtainable  on  the  market,  and  in  attempting  to  make  a 
quantity,  it  was  found  that  during  evaporation  in  a  carefully  purified 
solution,  the  sodium  chloride  would  attack  tinned  copper,  aluminum, 
and  several  grades  of  special  enameled  iron  to  such  an  extent  that 
the  crystals  when  redissolved  in  water  would  show  a  weighable 
