Am.  Jour.  Pharm.  \ 
October,  1900.  J 
Seidlitz  Powders. 
463 
Heated  at  74  °  C.  the  mixture  loses  water  and  carbon  dioxide,  at 
a  higher  temperature  is  decomposed,  froths,  becomes  brown,  and 
gives  off  inflammable  vapors  having  the  odor  of  burning  sugar, 
finally  leaving  a  residue  consisting  of  alkaline  carbonates  mixed 
with  carbon. 
With  silver  nitrate  test  solution  a  solution  of  the  mixture  yields 
a  white  precipitate,  which  becomes  black  on  boiling.  If  the  white 
precipitate  is  dissolved  by  the  addition  of  a  few  drops  of  ammonia 
water,  a  silver  mirror  will  be  produced  on  heating.  The  solution 
of  the  mixture,  acidified  with  acetic  acid,  yields  a  yellow  precipitate 
on  the  addition  of  sodium  cobaltic  nitrite  test  solution. 
Arsenic,  Lead,  Copper,  etc. — A  small  quantity  of  the  seidlitz  mix- 
ture slightly  supersaturated  with  hydrochloric  acid,  and  followed 
by  an  equal  volume  of  hydrogen  sulphide  test  solution,  should  not 
be  rendered  turbid. 
Iron,  Aluminum,  etc. — The  clear  filtrate  from  the  above  should 
not  be  rendered  turbid  on  slight  supersaturation  with  ammonia 
water. 
Chlorides. — If  1-2  grammes  of  seidlitz  mixture  be  dissolved  in  10 
c.c.  of  dilute  nitric  acid,  then  -5  c.c.  of  decinormal  silver  test  solu- 
tion added,  and  the  precipitate,  if  any,  removed  by  filtration,  the 
clear  filtrate  should  remain  unaffected  on  the  further  addition  of 
silver  nitrate  test  solution. 
Sulphate,  Sulphite  and  Hyposulphite. — If  2*5  grammes  of  seidlitz 
mixture  be  dissolved  in  11  c.c.  of  dilute  hydrochloric  acid,  then  «i 
c.c.  of  nitric  acid  and  -25  c.c.  of  decinormal  barium  chloride  test 
solution  added,  and  the  precipitate,  if  any,  removed  by  filtration, 
the  clear  filtrate  should  remain  unaffected  by  the  further  addition 
of  barium  chloride  test  solution. 
Calcium. — The  aqueous  solution  should  not  be  rendered  turbid 
by  ammonium  oxalate  test  solution. 
Sulphocyanate. — The  aqueous  solution  slightly  supersaturated 
with  hydrochloric  acid  should  not  be  colored  red  by  a  drop  of  ferric 
chloride  test  solution. 
Quantitative  Tests. — If  2  grammes  of  the  mixture  of  sodium 
bicarbonate  and  rochelle  salt  be  dissolved  in  water,  normal  sul- 
phuric acid  volumetric  solution  added  until  effervescence  ceases, 
and  the  solution  is  strongly  acid,  then  boiled  for  five  or  ten  minutes, 
phenolphtalein  test  solution  added,  and  the  excess  of  acid  neu- 
