ON  EFFERVESCING  POWDERS. 
51 
20  grains  of  the  crystallized  citric  acid  will  saturate  18  grains 
of  the  bicarbonate  of  ammonia,  the  quantity  of  which,  however, 
may  be  enlarged  if  a  more  decided  action  of  the  ammonia  is 
wanted. 
Sometimes,  though  as  yet  not  very  often,  if  Seidlitz  powders 
are  excepted,  effervescing  powders  are  used  to  cover  the  un- 
pleasant taste  of  some  medicines ;  in  this  view  they  are  mostly 
used  in  connection  with  Rochelle,  Epsom,  and  Glauber's  salt, 
the  bitterness  of  which  salts  is  to  a  certain  degree  masked,  par- 
ticularly if  taken  in  connection  with  lemon  syrup.    Meirieu  has 
proposed  to  administer  sulphate  of  quinine  in  this  manner,  by 
mixing  1  decigramme  of  it  (1.5  grains)  with  1  gramme  of  tar- 
taric acid,  and  in  another  paper  1.2  grammes  of  bicarbonate  of 
soda  and  8  grammes  sugar ;  the  quantity  of  the  acid  just  suffi- 
ces to  convert  the  soda  into  the  neutral  tartrate,  and  to  render 
the  quinine  easily  soluble,  which  is  intended  to  be  taken  with  its 
bitterness  masked  by  the  sugar  and  the  evolved  carbonic  acid. 
A  ferruginous  effervescing  powder  has  been  proposed  by  Colom- 
bat,  and  the  formula  for  it  published  by  Dorvault.    The  pow- 
ders are  made  by  mixing  2  grms.  (grs.  30.87)  sulphate  of  iron, 
6  grms.  (grs.  92.60)  tartaric  acid,  and  12  grms.  (3  drachms) 
sugar,  and  dividing  the  mixture  into  12  powders,  which  are  done 
up  in  white  paper ;  each  of  the  blue  papers  contains  5  grs.  of 
bicarbonate  of  soda  and  15  grs.  of  sugar.    A  reaction  at  first 
takes  place  between  the  iron  and  soda  salt,  resulting  in  some  sul- 
phate of  soda  and  bicarbonate  of  the  protoxide  of  iron,  which  is 
decomposed  together  with  the  rest  of  the  bicarbonate  of  soda  by 
the  tartaric  acid;  the  acid  is  just  within  the  fraction  of  not 
quite  2  grains  for  the  12  powders,  sufficient  to  produce  tartrate 
of  the  protoxide  of  iron  and  bitartrate  of  soda.    If  the  assertion 
of  many  practitioners  be  correct,  that  iron  exhibits  the  most 
useful  and  reliable  action  in  the  animal  body  when  administered 
in  the  state  of  protoxide,  the  above  prescription  might  perhaps 
be  found  very  beneficial  and  claim  the  attention  of  physicians. 
Tartrate  of  protoxide  of  iron  is  but  little  soluble  in  water,  and 
it  might  perhaps  be  thought  objectionable  on  that  account ;  it 
remains  to  be  seen,  however,  whether  bitartrate  of  soda  or  the 
carbonic  acid  does  not  act  as  a  solvent,  or  whether  the  digestive 
liquids  do  not  easily  decompose  it,  so  as  to  assimilate  the  iron. 
