Am.  Jour.  Pharm. 
May,  1904. 
Calcium  Glycerophosphate . 
213 
3  kilos  phosphoric  acid,  60  per  cent. 
3  kilos  600  grammes  glycerin  (sp.  gr.  i'24). 
Mix  together  and  keep  at  a  temperature  of  100-1100  C.  for  six 
days,  agitating  three  or  four  times  daily.  The  second  day  it  com- 
mences to  color  and  emit  fumes ;  the  fifth  day  it  will  have  turned 
brown  and  ceased  to  fume ;  on  the  seventh  day  it  is  allowed  to  cool, 
and  is  then  viscous  and  transparent.  After  cooling,  the  free  acid  is 
neutralized  by  mixture  of  500  grammes  calcium  carbonate  in  2  kilos 
of  water,  and  allowed  to  settle  two  or  three  hours,  when  more  of  the 
chalk  mixture  is  added  and  the  process  repeated  until  all  the  acid  is 
saturated,  which  generally  takes  about  two  days.  The  mixture  is 
filtered,  and  the  filtrate  exactly  neutralized  by  means  of  90  per  cent, 
alcohol.  The  precipitate  which  forms  settles  very  rapidly;  after 
about  an  hour  the  supernatant  fluid  is  decanted,  the  precipitate  is 
washed  and  drained.  It  is  then  redissolved  in  cold  water,  filtered 
and  evaporated  at  a  low  temperature.  The  salt  thus  obtained  is  a 
white  crystalline  powder,  soluble  in  15  parts  of  cold  water,  almost 
insoluble  in  boiling  water,  insoluble  in  alcohol. 
The  reactions  involved  in  the  manufacture  of  calcium  glycero- 
phosphate are  represented  by  the  following  equations : 
(1)    Glycerin -J- Phosphoric  acid  =  Glycerophosphoric  acid 4- Water 
C3H5(OH)3+       H>04        =  C,H,PO,  +  H20 
(2)  Glycerophosphoric  acid  -f-  Calcium  hydroxide  -f  Water  = 
C3H9P06  +         CaOH  +    H20  = 
Glycerophosphate  of  calcium 
C3H8CaP06+  2  H20 
The  theoretical  amount  of  calcium  oxide  in  calcium  glycerophos- 
phate is,  therefore,  about  22-66  per  cent. 
The  estimation  of  this  ingredient  (calcium)  is  the  keynote  of  the 
examination  of  calcium  glycerophosphate,  for  if  true  glycerophos- 
phoric acid  is  not  formed  in  the  first  reaction,  the  free  phosphoric 
acid  left  uncombined  will  require  a  larger  percentage  of  calcium  for 
neutralization,  and  will  thus  be  shown  by  this  determination.  A 
sample  of  an  English  brand  of  calcium  glycerophosphate  examined 
contained  33  05  per  cent,  of  calcium  oxide  and  was  slightly  acid  in 
reaction.    This  would  tend  to  prove  the  above  assumption. 
In  estimating  the  calcium,  I  followed  the  usual  method  as  given 
