Am.  Jour.  Pharm. 
June,  19 17. 
}    Pharmacy  of  Calcium  Glycerophosphate. 
247 
a  (anhydrous)  1 : 22  at  200. 
a         "         1 : 108  at  ioo° 
a         "         1:22.4  at  160. 
/?         "         1:60  at  200. 
(Power  and  Tutin.2) 
Both  isomers  are  insoluble  in  alcohol. 
Acids  increase  the  solubility  of  calcium  glycerophosphate  in 
water  but  those  acids  which  form  insoluble  calcium  salts  gradually 
produce  a  precipitate  in  the  solution,  which  is  undesirable.  In  addi- 
tion, any  admixture  with  acid  increases  the  rate  of  hydrolysis  of 
the  glycerophosphoric  acid  so  that,  even  in  the  presence  of  acids 
which  do  not  form  insoluble  calcium  salts,  a  precipitate  of  secondary 
calcium  phosphate  may  be  produced  unless  the  proportions  of  acid 
and  salt  are  so  adjusted  that  the  soluble  primary  calcium  phosphate 
is  formed.  Lactic  acid  appears  to  be  eminently  fitted  for  this  pur- 
pose. Citric,  phosphoric,  and  tartaric  acids  are  objectionable  be- 
cause they  lead  to  precipitation  and  other  acids  are  excluded  for 
therapeutic  reasons  or  pharmaceutical  inelegance. 
1.  Influence  of  Alcohol  upon  the  Solubility  of  Calcium  Glycero- 
phosphate in  Water. — For  this  purpose  a  solution  made  by  saturat- 
ing water  with  the  salt  at  25 0  was  used.    The  solubility  was  1 :  31.59. 
A.  To  35  mils  of  solution  1.5  mils  of  alcohol  were  added.  A 
flocculent  precipitate  immediately  appeared.  The  mixture  was 
shaken  and  allowed  to  stand  until  precipitation  was  complete.  The 
precipitate  was  filtered  off,  washed  with  a  small  quantity  of  5  per 
cent,  alcohol,  dried  at  no°,  and  weighed.    Wt.  ppt.  0.2308  Gm. 
B.  To  34.7  mils  of  mother  liquor  from  experiment  A  1.9  mils 
of  alcohol  were  added.  A  precipitate  was  produced  which  was 
treated  as  in  A  except  that  it  was  washed  with  10  per  cent,  alcohol. 
Wt.  ppt.  0.2195  Gm. 
C.  To  33.8  mils  of  nitrate  from  experiment  B  0.9  mils  of  alcohol 
were  added.  The  precipitate  produced  was  treated  as  in  A  and  B 
except  that  it  was  washed  with  12  per  cent,  alcohol.  Wt.  ppt. 
0.1366  Gm. 
Solution  A  contained  about  5  per  cent,  alcohol  by  volume,  B 
about  10  per  cent,  and  C  about  12  per  cent.  The  solubility  of  cal- 
cium glycerophosphate  in  diluted  alcohol  at  250  is  therefore: 
2  Jour.  Chem.  Soc,  87,  240  (1905). 
Experimental. 
