304 
Sodium  Phosphate  Solution. 
Am.  Jour.  Pharm. 
June,  1898. 
sodium  phosphate.  The  one  most  generally  employed  is  that  of  a 
"  solution  of  citro-phosphate  of  sodium,"  originated  by  William  C. 
Wescott  (American  Journal  of  Pharmacy,  1896,  256),  as  a  result  of 
his  analysis  of  a  widely-advertised  proprietary  preparation,  claimed 
by  the  manufacturers  to  contain,  in  each  fluidram,  85  grains  of  com- 
bined sodium  phosphate,  citric  acid,  and  sodium  nitrate. 
Wescott's  formula  is  as  follows  : 
Sodium  phosphate,  crystals   7  ozs.  (Troy)  290  grains. 
Citric  acid  475  grains. 
Sodium  nitrate   73  grains. 
Water,  a  sufficient  quantity  to  make    ...     8  fluidounces. 
Triturate  the  salts  and  acid  until  they  liquefy,  and  add  the  water. 
Now,  it  will  be  noticed  that,  in  this  formula,  the  proportion  of 
citric  acid  used  to  anhydrous  phosphate  is  very  large,  relatively,  i.e., 
about  one-third.  Three  thousand  six  hundred  and  fifty  grains  of 
crystalline  salt  would  yield  1,449  grains  of  anhydrous  salt,  and  for 
this  475  grains  of  citric  acid  is  directed. 
The  question  that  naturally  arises  at  this  point  is,  "  What  chemi- 
cal change  ensues  in  the  making  of  this  preparation?"  In  the 
writer's  opinion,  part  of  the  official  sodium  phosphate,  or  acid  phos- 
phate, is  changed  into  sodium  diacid  phosphate,  and  sodium  citrate 
according  to  the  following  reaction : 
3Na2HP04.i2H20  +  H3C6H507H20  = 
1071-96  2095 
3NaH2P04  +  Na3C6H507  +  37H20. 
359-4  257-54  664-52 
If  this  theory  be  correct,  it  will  be  seen  that  a  part  of  the  sodium 
phosphate  is  changed  to  sodium  citrate.  Assuming  that  the  reaction 
given  is  correct,  it  will  be  found  by  equation  that,  in  the  8  fluid- 
ounces  of  solution,  475  grains  of  citric  acid  are  changed  to  584  grains 
of  sodium  citrate,  or  about  9  grains  of  the  latter  to  each  fluidram. 
The  question  that  we,  as  pharmacists,  should  like  to  ask  of  you, 
as  physicians,  is  this,  u  Whether  or  not  the  presence  of  sodium 
citrate  and  of  sodium  nitrate  is  ever  contraindicated,  therapeutically, 
when  the  use  of  sodium  phosphate  is  indicated  ?  "  If  they  are,  then 
a  formula  should  be  devised,  whereby  this  objection  shall  be  elimi- 
nated. 
For  more  than  a  year  past,  the  writer  has  used  in  the  Philadel- 
