Am.  Jour.  Pharm.  l 
February,  1902.  J 
Seidlitz  Powders. 
77 
which  the  quantitative  work  was  taken  up  ;  the  white  powders  or  the 
tartaric  acid  were  first  examined,  followed  by  the  blue  or  the  Seid- 
litz mixture. 
Quantitative  Tests. — The  volumetric  solutions  used  for  these  tests 
were  : 
The  tartaric  acid  was  titrated  with  sodium  hydrate  volumetric 
solution,  phenolphtalein  as  indicator,  as  mentioned  in  experiments, 
the  calculation  being  made  in  the  regular  way. 
Ihe  Seidlitz  Mixture  was  analyzed  by  first  estimating  the  sodium 
bicarbonate  by  a  carbon-dioxide  determination,  then  the  Rochelle 
salt  by  ignition  and  titration. 
This  method  will  be  best  understood  by  carrying  through  an 
example,  thus : 
.  If  1722  grammes  of  Seidlitz  mixture  be  placed  in  a  carbon- 
dioxide  apparatus  and  a  slight  excess  of  hydrochloric  acid  used  for 
decomposition,  it  will  yield  0-225  grammes  of  carbon-dioxide  gas. 
The  amount  of  sodium  bicarbonate  is  then  calculated  from  this 
weight  of  C02  as  follows :  , 
(C02  43-85) :  (NaHCO.3  83-85)  :  :  -225  :  -42985  grammes  of  NaHC03, 
then, 
1722  :  -42985  :  :  100  :  24-96  per  cent,  of  NaHC03. 
For  the  Rochelle  salt  estimation  another  portion  of  1-722  grammes 
is  taken  and  ignited  carefully  in  a  small  crucible  to  entire  carboniza- 
tion. This  ignited  mass  is  then  taken  up  with  water,  all  of  the 
washings  being  carefully  collected.  This  solution  now  contains 
the  carbonates  from  the  Rochelle  salt,  also  that  from  the  sodium 
bicarbonate.  This  solution  is  titrated  directly  with  the  sulphuric 
acid  volumetric  solution,  using  methyl  orange  as  indicator.  The 
solution  of  carbonates  required  74-75  c.c.  of  the  sulphuric  acid 
solution. 
From  this  must  be  deducted  the  number  of  c.c.  required  for  the 
carbonate  from  the  sodium  bicarbonate  in  order  to  determine  the 
Sodium  hydrate,  of  which  1  c.c, 
Sulphuric  acid,  of  which  1  c.c. 
/  '05633  grammes  NaOH 
1-01055       «  H2C4H406 
(  'O09327  grammes  H2S04 
\  -004184      "  co2 
(  -2684  «  KNaC4H40( 
