54 
ON  EFFERVESCING  POWDERS. 
water  is  used  for  the  menstruum.  Bicarbonate  and  bitartrate 
of  soda  must  be  used  in  the  proportion  of  9-20  to  furnish  a 
neutral  salt.  If  the  ingredients  are  pulverized  separately  and 
afterwards  mixed  with  finely  powdered  sugar,  the  mixture  will 
keep  very  well  in  a  paper  box,  with  no  other  precaution  except 
to  keep  it  away  from  dampness. 
In  a  similar  manner  effervescing  powders  may  be  prepared 
with  bicarbonate  of  ammonia,  of  which  14  parts  are  necessary  to 
completely  saturate  15  parts  of  tartaric  acid,  so  as  to  form  the 
neutral  tartrate  of  ammonia,  or  30  parts  of  the  acid  are  required 
if  the  formation  of  bitartrate  of  ammonia  is  desired.  7  parts 
of  bicarbonate  of  ammonia  will  saturate  18 J  parts  of  bitartrate 
of  potassa,  and  3  parts  of  the  carbonate,  8J  parts  of  bitartrate 
of  soda,  in  the  first  case  forming  the  tartrate  of  ammonia  and 
potassa,  in  the  latter  tartrate  of  ammonia  and  soda.  The  same 
results  may  be  arrived  at,  if  bitartrate  of  ammonia  be  used,  and 
it  may  suffice  simply  to  state  here  the  required  proportions : 
16  parts  of  it  saturate  7  parts  of  bicarbonate  of  ammonia, 
forming  neutral  tartrate  of  ammonia. 
2  parts  of  it  saturate  1  part  of  bicarbonate  of  soda,  forming 
tartrate  of  soda  and  ammonia. 
4  parts  of  it  saturate  2J-  parts  of  bicarbonate  of  potassa, 
forming  tartrate  of  potassa  and  ammonia. 
3  parts  of  it  saturate  1  part  of  dry  carbonate  of  soda,  forming 
tartrate  of  soda  and  ammonia. 
An  effervescing  powder  containing  magnesia  was  formerly 
more  extensively  used  in  Europe  than  at  present ;  it  consisted 
of  carbonate  of  magnesia  sjij,  tartaric  acid  3ss,  sugar  31,  oil  of 
lemon  gtt.  iij.  An  effective  and  very  pleasant  cathartic  may  be 
prepared  from  the  following  ingredients  :  carbonate  of  magnesia, 
citric  acid,  sugar,  aa  3ij  to  giij,  oil  of  lemon  gtt.  ij.  The  ingre- 
dients are  to  be  separately  rubbed  into  a  fine  powder  and  then 
mixed.  Thus  extemporaneously  prepared  and  soon  taken,  it 
makes  a  pleasant  drink  and  is  a  good  cathartic.  The  pow- 
der is  to  be  stirred  into  about  half  a  pint  of  water,  when  chemical 
reaction  will  instantly  commence ;  when  it  has  fairly  set  in,  it 
should  be  taken  at  once.  I  have  omitted  to  make  experiments 
with  regard  to  its  keeping.  It  remains  to  be  seen,  and  experi- 
ments ought  to  be  made,  whether  it  may  be  preserved  unaltered 
