602  Commercial  Sodium  Bicarbonate.       i^"^' j^^^.'J^^^ 
as  yet  not  been  proven,  and  it  is  not  improbable  that  a  number  of  dif- 
ferent compounds  may  ultimately  be  isolated,  having  similar,  yet  not 
identical  properties  ;  in  other  words,  that  the  coloring  matters  of  flow- 
ers differ  to  a  greater  extent  than  the  earlier  investigations  seemed 
to  indicate. 
ANALYSIS  OF  COMMERCIAL  SODIUM  BICARBONATE. 
A  contribution  from  the  Chemical  Laboratory  of  the  Philadelphia  College  of 
Pharmacy. 
By  Hermann  M.  J.  Schroeter,  Ph.  G. 
Read  at  the  Pharmaceutical  Meeting,  November  20th. 
The  Pharmacopoeia  directs  two  kinds  of  bicarbonate  of  sodium : 
"  Sodii  bicarbonas  and  "  Sodii  bicarbonas  venalis.''  The  commer- 
cial article  as  produced  now  on  a  large  scale  and  found  in  the  market 
is  believed  to  be  quite  pure  and  is  used  very  extensively.  If  the  com- 
mercial product  is  found  to  be  sufficiently  pure  to  be  used  for  most 
purposes,  it  would  obviate  the  direction  of  two  kinds  by  the  Pharma- 
copoeia. It  is  also  believed  that  the  commercial  article  is  in  most 
cases  used  by  the  pharmacist  and  by  some  exclusively.  The  object  of 
this  analysis  is  to  show  the  difference  existing  between  the  commercial 
and  the  chemically  pure  article  as  now  obtainable  in  the  market. 
Whether  any  of  the  commercial  products  respond  to  the  requirements 
of  the  pure,  will  be  shown  ;  and  also  whether  the  commercial  kind  is 
sufficiently  pure  for  most  purposes. 
The  commercial  bicarbonate  is  prepared  on  a  large  scale  among 
other  processes  by  saturating  sodium  carbonate  with  carbon  dioxide. 
The  excess  of  normal  salt  is  then  washed  out  with  water,  the  acid  salt 
being  much  less  soluble  in  water.  Accordingly  the  commercial  pro- 
duct contains  always  a  certain  amount  of  the  normal  salt.  It  is  also 
stated  that  a  small  amount  of  carbonate,  at  least  1  per  cent,  is  unavoid- 
ably present  in  every  bicarbonate;  this  is  due  to  the  loss  of  someCOg 
on  drying  ihe  salt  and  by  age.  By  repeated  washing  of  the  commer- 
cial product,  all  of  the  normal  salt  is  eliminated,  besides  some  impuri- 
ties, as  chlorides  and  sulphates ;  but  on  drying  even  without  applica- 
tion of  heat,  by  moistening  the  washed  salt  with  alcohol  and  then 
drying  between  folds  of  filter  paper,  it  undergoes  partial  decomposition 
and  contains  about  1  per  cent,  of  normal  carbonate. 
The  following  analysis  consists  of  an  investigation  of  16  brands  of 
