466 
Granular  Effervescent  Salts. 
J  A.m.  Jour.  Pharm 
t     October.  1903. 
EFFERVESCENT  SODIUM  PHOSPHATE. 
Sodium  phosphate,  uneffloresced  crystals 
Sodium  bicarbonate,  dried  and  powdered 
Tartaric  acid,  dried  and  powdered  .  .  . 
Citric  acid,  uneffloresced  crystals  .  .   .  . 
477 
252 
162 
500  grammes. 
Dry  the  sodium  phosphate  on  a  water-bath  until  it  ceases  to  lose 
weight;  after  powdering  the  dried  salt,  mix  it  intimately  with  the 
citric  acid  and  tartaric  acid,  then  thoroughly  incorporate  the  sodium 
bicarbonate. 
The  mixed  powders  are  now  ready  for  granulation.  The  change 
in  manipulation  which  is  suggested  to  replace  that  usually  followed, 
requires  either  a  gas  stove  or  a  blue-flame  coal-oil  stove,  and  one  of 
the  small  tin  or  sheet-iron  ovens  which  are  so  largely  used  with 
these  stoves.  The  stove  itself  will  be  found  in  almost  every  drug 
store,  and  the  oven  costs  but  from  $\  to  $2. 
The  oven  is  heated  to  about  200°  F.  (the  use  of  a  thermometer  is 
desirable  at  first,  but  one  will  quickly  learn  how  to  regulate  the 
flame  to  produce  the  desired  temperature),  and  the  previously  mixed 
powders  are  placed  on,  preferably,  a  glass  plate,  which  has  been 
heated  with  the  oven,  about  y2  pound  being  taken  at  a  time, 
dependent  upon  the  size  of  the  oven.  The  door  of  the  oven  is  now 
closed  for  about  one  minute,  and,  when  opened,  the  whole  mass  will 
be  found  to  be  uniformly  moist  and  ready  to  pass  through  a  suitable 
sieve,  the  best  kind  and  size  being  a  tinned  iron  No.  6.  This  moist, 
granular  powder  may  then  be  placed  upon  the  top  of  the  oven, 
where  the  heat  is  quite  sufficient  to  thoroughly  dry  the  granules, 
and  the  operator  may  proceed  immediately  with  the  next  lot  of 
mixed  powder,  easily  granulating  10  or  more  pounds  within  an  hour. 
Sugar  has  often  been  proposed  as  an  addition  to  these  salts,  but 
experience  has  shown  that  the  slight  improvement  in  taste,  which  is 
sometimes  questioned,  does  not  offset  the  likelihood  of  darkening, 
which  is  apt  to  occur  when  the  salt  is  being  heated,  or  the  change 
in  color  after  it  has  been  made  several  months. 
It  should  be  remembered,  too,  that  in  making  a  granular  effer- 
vescent salt  by  the  method  which  depends  upon  the  liberation  of 
water  of  crystallization,  a  loss  in  weight,  amounting  to  about  10  per 
cent.,  will  be  experienced.  This  is  due,  in  part,  to  the  loss  of  water 
which  is  driven  off,  and  also  to  a  trifling  loss  of  carbon  dioxide  when 
the  powder  is  moistened. 
