244        Pharmacy  of  Calcium  Glycerophosphate.    {  A™u  J°Ui9f7harm- 
National  Formulary  obscures  the  fact  of  the  insolubility  of  the 
calcium  glycerophosphate  and  the  pharmacist  may  be  led  to  believe — 
unless  he  be  of  a  critical  turn  of  mind — that  each  liter  of  his  finished 
elixir  contains  16  Gm.  of  calcium  glycerophosphate. 
The  Compound  Elixir  of  the  Glycerophosphates,  N.  F.  IV,  was 
prepared  with  rigid  adherence  to  the  directions  except  that  the 
purified  talc  was  omitted  and  the  mixture  was  not  immediately 
filtered.  A  large  proportion  of  the  calcium  salt  was  found  out  of 
solution,  not  having  been  dissolved  and  then  precipitated  on  the 
addition  of  the  alcohol  which  might  have  happened.  It  had  never 
been  dissolved  and  no  other  manipulation  would  cause  its  solution. 
This  mixture  was  allowed  to  stand  two  days  at  room  temperature 
with  occasional  shaking  in  order  that  there  might  be  no  doubt  of  the 
establishment  of  equilibrium.    A  considerable  precipitate  remained. 
The  mixture  was  now  divided  into  four  equal  portions.  The 
first  portion  was  filtered,  made  up  to  volume  through  the  filter, 
bottled  and  set  aside  for  analysis.  To  the  other  three  portions 
lactic,  citric,  and  phosphoric  acids  were  severally  added  in  small 
amounts  until  the  insoluble  matter  was  dissolved.  4  Gm.  of  citric 
acid  per  liter  dissolved  the  precipitate  in  one  portion.  This  solution 
began  to  deposit  calcium  citrate  within  a  week  and  the  precipitation 
continued  until  the  acid  was  exhausted.  A  third  portion  required 
40  mils  of  U.  S.  P.  phosphoric  acid  per  liter  to  completely  dissolve 
the  precipitate  and  this  solution  quickly  became  cloudy  as  a  heavy 
precipitate  settled  out.  In  the  f  ourth  portion  the  undissolved  calcium 
salt  was  brought  into  solution  by  lactic  acid  in  the  proportion  of  30 
mils  per  liter  and  this  solution,  which  was  not  filtered,  shows  only  a 
barely  perceptible  cloudiness  after  standing  three  months.  This 
mixture  now  contains  40  mils  per  liter  of  lactic  acid  which  is  suffi- 
cient to  dissolve  and  retain  in  solution  16  Gm.  per  liter  of  commercial 
calcium  glycerophosphate. 
Lest  the  use  of  the  term  "  commercial "  in  the  above  paragraph 
lead  to  misunderstanding  let  me  add  that  the  adjective  was  used  to 
designate  the  mixture  of  isomers  found  in  commerce  which  conforms 
to  the  requirements  of  the  Pharmacopoeia.  All  of  the  materials 
used  in  this  investigation  complied  with  the  standards  of  the  U.  S.  P. 
IX  or  N.  F.  IV,  unless  otherwise  stated. 
The  first  portion  was  analyzed  for  calcium  glycerophosphate. 
29.57  mils  gave  0.00826  Gm.  of  calcium  oxide  corresponding  to  11.72 
Gm.  calcium  glycerophosphate  per  liter,  or  73.36  per  cent,  of  the 
formulated  amount. 
