AKnJe°Ui9?7harm'  ^    Pharmacy  of  Calcium  Glycerophosphate.  249 
B.  On  the  same  date  100  mils  of  a  saturated  solution  of  calcium 
glycerophosphate  in  water  made  by  the  second  method  was  prepared 
and-  set  beside  the  above  solution,  both  being  securely  stoppered. 
This  solution  precipitated  in  three  days  and  at  the  end  of  a  month 
there  was  fully  ten  times  as  much  precipitation  in  the  aqueous  as 
in  the  glycerin  solution.  These  experiments  show  roughly  that, 
while  glycerin  does  not  prevent  the  hydrolysis  of  the  calcium  glycero- 
phosphate, it  does  retard  it. 
C.  1.75  Gm.  calcium  glycerophosphate  were  treated  with  100 
mils  of  a  25  per  cent,  solution  of  glycerin  in  water.  The  salt  was 
not  quite  completely  soluble.  This  quantity  was  just  soluble  in  100 
mils  of  water. 
D.  To  the  foregoing  solution  0.5  mil  of  lactic  acid  were  added. 
The  remainder  of  the  calcium  salt  dissolved.  The  solution  pre- 
cipitated in  the  same  fashion  as  in  experiment  A  and  to  the  same 
extent.  This  indicates  that  glycerin  retards  the  hydrolysis  in  acid 
solutions  also. 
4.  Joint  Influence  of  Alcohol  and  Glycerin  on  the  Solubiliy  of 
Calcium  Glycerophosphate. — A.  An  aqueous  mixture  containing 
12.5  per  cent,  of  alcohol,  and  25  per  cent,  of  glycerin  was  employed. 
100  mils  were  added  to  1.75  Gm.  of  the  calcium  salt.  Very  little 
dissolved.  3  mils  of  lactic  acid  were  sufficient  to  effect  the  solution. 
This  solution  did  not  precipitate ;  in  three  months  a  small  cloudiness 
only  was  visible. 
5.  Influence  of  sodium  glycerophosphate  solution  upon  the  solu- 
bility of  the  calcium  compound. 
A.  An  aqueous  solution  of  the  U.  S.  P.  solution  of  sodium 
glycerophosphate  which  contained  40  Gm.  per  liter  (or  the  same 
strength  that  is  used  in  the  N.  F.  compound  elixir)  was  employed 
to  dissolve  1.75  Gm.  of  the  calcium  salt.  Required  178.85  mils  of 
solvent.  Solubility,  1 :  102.2  at  25 °.  The  calcium  compound  is, 
therefore,  only  half  as  soluble  in  this  solvent  as  it  is  in  water.  In 
addition,  this  solution  hydrolyzed  rapidly. 
6.  Influence  of  alcohol,  glycerin,  and  sodium  glycerophosphate 
upon  the  solubility  of  calcium  glycerophosphate  in  lactic  acid  solution. 
A.  1.75  Gm.  of  the  calcium  salt  were  treated  with  a  solvent 
composed  of  12.5  per  cent,  alcohol  by  vol.,  25  per  cent,  glycerin,  40 
Gm.  per  liter  of  sodium  glycerophosphate  solution  U.  S.  P.  and  I 
per  cent,  of  lactic  acid.  Required  294  mils  of  solvent.  Solubility, 
1 : 168  at  250. 
