392  Caustic  Soda  Sold  as  Caustic  Potash.  {AmAi°^uimm' 
^CRUDE   CAUSTIC   SODA  SOLD  IN  THE  MARKET  AS 
CAUSTIC  POTASH. 
By  Carl  E.  Smith. 
(Report  from  Research  Committee  D,  Section  II. ,  of  the  Committee  of  Revision 
of  the  U.  S.  Pharmacopoeia.) 
In  the  course  of  an  investigation  into  the  quality  of  commercial 
crude  caustic  potash,  the  writer  has  recently  examined  five  samples 
that  proved  to  be  nothing  more  nor  less  than  caustic  soda  of  vary- 
ing degrees  of  purity.  Dr.  Charles  Rice,  who  requested  the  writer 
to  investigate  this  subject,  obtained  these  samples  from  various 
sources  through  which  the  grocery  trade  is  supplied.  They  appear 
to  be  representative  of  what  is  sold  in  New  York  City  as  potash  to 
such  consumers  as  are  not  supposed  to  test  their  purchases  chemi- 
cally. The  potash  present  was  no  larger  in  amount  than  that  which 
crude  soda  might  naturally  contain,  and  in  some  cases  the  quantities 
of  chlorides  and  sulphates  were  extraordinarily  large.  As  the  two 
alkalies  rather  closely  resemble  each  other  physically,  such  a  sub- 
stitution may  easily  be  overlooked,  and,  as  some  of  these  products 
present  a  very  good  appearance,  pharmacists  may  sometimes  be 
tempted  to  use  potash  obtained  from  such  sources  for  the  prepara- 
tion of  potassium  bromide  or  iodide,  soft  soap,  etc.,  without  con- 
sidering a  previous  chemical  examination  necessary.  In  some  such 
cases  the  substitution  may  not  even  be  detected  during  the  process 
of  manufacture,  as  in  the  case  of  soft  soap. 
The  following  table  indicates  the  composition  of  the  five  samples, 
the  potash  calculated  as  sulphate,  in  accordance  with  a  rule  formu- 
lated by  Fresenius  : 
A. 
B. 
C. 
D. 
n. 
Per  cent. 
Per  cent. 
Per  cent. 
Per  cent. 
Per  cent. 
65 '9 
828 
7r6 
87-0 
85-2 
4  75 
53 
3-i8 
3-iS 
^  e> 
170 
7  "45 
4-2 
5 '5 
i'57 
2*04 
9  "25 
2-S 
2'3 
"  silicate  
0-58 
o-33 
0-4 
0-13 
°'55 
2  4 
0*58 
4'35 
073 
0-38 
7'o 
3*4 
6-4 
47 
2'4 
021 
none 
o-i7 
trace 
trace 
