330 
Bismuth  Subgallate. 
(  Am.  Jour.  Pharm. 
t       July,  1899. 
No.  7  contained  many  microscopical  crystals.  The  process  given 
by  H.  Causse1  is  said  to  yield  a  crystalline  product.  The  method 
is,  however,  not  suitable  for  practical  purposes,  and  the  writer  is  of 
the  opinion  that  the  above  crystalline  product  was  not  obtained  by 
this  process.  At  all  events,  the  amorphous  is  preferred,  since  it  is 
less  irritating  to  tender  surfaces. 
The  reaction  of  bismuth  subgallate  on  litmus  paper  appears  to  be 
anomalous.  On  treating  this  chemical  with  water,  filtering  and  then 
ascertaining  the  reaction  of  the  filtrate  on  litmus,  it  will  generally 
be  found  neutral.  But,  if  blue  litmus  paper  be  moistened  and  then 
laid  on  a  small  amount  of  the  bismuth  subgallate,  it  will  be  found 
that  in  a  longer  or  shorter  time  an  acid  reaction  will  manifest  itself. 
The  bismuth  oxide  was  estimated2  by  ignition  in  a  porcelain  cru- 
cible and  the  reduced  metal  oxidized  either  by  prolonged  incinera- 
tion or  nitric  acid  or  ammonium  nitrate.  It  was  found  that  pro- 
longed heating  gave  results  identical  with  those  obtained  by  the 
use  of  either  ammonium  nitrate  or  nitric  acid  and  with  much  less 
inconvenience.  When  nitric  acid  is  used,  great  care  must  be  exer- 
cised in  evaporating  all  of  the  moisture  before  applying  the  burner, 
otherwise  there  will  be  loss  by  spirting,  and  in  the  cooling  and  re- 
heating there  is  much  danger  in  cracking  the  crucible.  With  am- 
monium nitrate  there  is  less  chance  of  loss  by  either  spirting  or 
breaking  of  crucible,  but  the  writer  much  prefers  to  somewhat 
prolong  the  heating.  With  a  little  practice  the  operator  can  easily 
see  when  oxidation  is  complete. 
The  solubility  of  this  bismuth  salt  in  the  fixed  alkaline  hydrates 
is  a  distinct  advantage.  Some  claim  that  it  is  soluble  in  the  alka- 
line carbonates  also,  but  in  this  the  writer  has  not  been  successful. 
There  seems  to  be  some  solution,  but  not  of  such  an  extent  as  to 
be  useful.    Bismuth  subtannate  is  also  soluble  in  a  10  per  cent. 
1  1893,  Comp.  rend.,  117,  232  ;  Chem.  Ztg.,  17,  216. 
2  Note — Since  writing  the  above,  Duyk  (Bull.  Acad.  Med.  Belg.)  advises  that 
the  bismuth  be  estimated  as  an  oxalate,  since  oxalic  acid  possesses  the  property 
of  replacing  all  other  acids  in  combination  with  bismuth.  Bismuth  oxalate 
(BiC2H4OH)  theoretically  contains  66*56  per  cent,  of  bismuth,  and  it  is  claimed 
to  be  of  quite  constant  composition,  from  whatsoever  source  obtained.  Duyk 
advises  the  following  procedure  :  Into  a  suitable  vessel  place  about  1  gramme 
of  the  powdered  substance,  add  from  30  to  40  centigrammes  of  oxalic  acid,  warm 
gently,  add  100  c.c.  of  water,  boil  a  few  minutes  and  set  aside.  Collect  the 
precipitate  on  a  tared  filter  paper,  wash  with  warm  water  and  dry  at  no°  C. 
