66 
PHARMACEUTICAL  APPLICATION  OF  GLYCERINE. 
of  iron  may  be  made  by  dissolving  separately,  each  in  2  ounces 
of  glycerine,  76  grains  of  sulphate  of  iron  and  about  60  grains 
of  carbonate  of  potash,  and  mixing  the  solutions.  The  result 
•will  be  a  pale-green  solution  of  carbonate  of  iron,  containing  1 
gr.  in  fei.,  which  will  keep  a  considerable  time  without  change. 
The  carbonate  of  iron  is  thrown  down  as  a  flocculent  precipitate 
on  the  addition  of  water.  Gum  Ammoniacum  forms  a  white 
creamy  emulsion  with  glycerine,  in  the  proportion  of  ^i.  to  f  ^  i., 
which,  according  to  Demarquay,  does  not  separate.  I  imagined 
this  might  be  useful  for  the  instantaneous  production  of  a  kind 
of  Mist.  Ammoniaci,  but  the  result  of  my  experience  is  that  the 
resinous  part  of  the  Ammoniacum  gradually  separates  and  rises 
to  the  surface,  leaving  an  opalescent  solution  of  the  gummy  con- 
stituents below.  There  is  one  other  use  for  glycerine  which 
must  not  be  overlooked, — that  of  an  excipient  in  pill-masses. 
Alone  or  diluted  with  an  equal  weight  of  water  it  is  decidedly 
the  best  thing  for  "  making  up  "  pepsine  and  vegetable  powders, 
care  being  taken  not  to  add  too  much,  and  to  thoroughly  knead 
the  mass.  Pills  made  with  this  do  not  become  hard,  and  are 
therefore  always  in  a  condition  to  be  readily  dissolved  in  the 
stomach.  A  two-ounce  wide-mouthed  bottle  fitted  with  a  cork 
perforated  in  two  places,  through  one  of  which  a  piece  of  quill 
is  inserted  for  dropping  the  glycerine  from,  will  be  found  a  very 
serviceable  adjunct  to  the  dispenser's  board. 
Glycerine  has  been  honored  with  a  place  in  the  British 
Pharmacopoeia,  where,  however,  it  has  only  been  thought  worthy 
of  acting  as  a  solvent  for  the  tannin  in  »  Suppositoria  Tannici." 
The  test  there  given  is  that  it  shall  have  a  density  of  1-26  (the 
new  Pharmacopoeia  of  the  United  States  gives  1-25).  Price's  is 
almost  the  only  sample  I  have  met  with  which  reaches  this 
standard,  the  specimens  of  foreign  glycerines  I  have  examined 
being  considerably  below  the  mark,  and,  with  one  exception, 
having  a  disagreeable  odor.  This  odor  may  easily  be  detected 
by  rubbing  a  few  drops  on  the  back  of  the  hand.  One  of  the 
worst  of  these  importations  was  advertised  as  ««  equal  to  Price's 
in  every  respect."  I  have  not  detected  much  inorganic  impuri- 
ties in  the  foreign  glycerines,  and  the  presence  of  water  would 
be  of  comparatively  little  import,  if  it  were  possible  to  free  them 
from  the  well-known  rancid  odor,  which  renders  them  totally 
