558 
Inorganic  Chemistry  of  the  U.S. P. 
f  Am.  Jour.  Pharm. 
i   December,  1905. 
More  frequently  we  see  the  formula  of  this  salt  written  Fe5(OH)& 
when  the  iron  atom  is  assumed  to  be  quadrivalent,  or  pseudo-triva- 
lent.  According  to  this  view  the  constitution  of  ferric  hydroxide  is 
graphically  represented  thus 
/  O— H 
/  O— H 
Fe  —  O— H 
I 
Fe  —  O— H 
\  O — H 
\0— H 
There  are  good  reasons  for  believing  that  the  atoms  of  iron  as  well 
as  those  of  chromium  and  manganese  have  trivalent  power,  in 
which  case  ferric  hydroxide  would  be  correctly  represented  by  the 
formula  Fe(OH)3 ;  with  our  present  knowledge,  however,  it  is  diffi- 
cult to  say  which  of  these  views  is  correct.  Ferri  hydroxidum, 
U.S.P.,  if  used  as  an  arsenical  antidote  must  be  freshly  prepared  to 
be  of  the  most  benefit,  but,  before  using,  care  should  be  taken  to 
completely  remove  all  excess  of  ammonia  which,  being  a  caustic,  is 
itself  harmful.  The  thorough  washing  of  the  precipitated  ferric 
hydroxide  for  the  removal  of  ammonia  cannot  be  quickly  enough 
done,  when,  as  is  usually  the  case,  the  antidote  must  be  administered 
without  delay,  hence  it  is  recommended  to  employ  Ferri  Hydroxidum 
cum  Magnesii  Oxido.  This  latter  preparation  was  formerly  official 
under  the  name  of  Ferri  oxidum  hydratum  cum  magnesia.  It  is 
prepared  by  adding  a  mixture  of  magnesium  oxide  and  water  to  a 
diluted  solution  of  ferric  sulphate.  The  reaction  which  takes  place 
results  in  the  formation  of  ferric  hydroxide  and  magnesium  sulphate. 
There  is  no  necessity  for  washing,  and  the  mixture  can  be  given  at 
once,  as  the  presence  of  the  magnesium  sulphate  is  an  advantage 
rather  than  otherwise. 
Liquor  Sodce  Chlorates  is  now  called  Liquor  Soda  Chlorinates. — 
The  method  of  preparation  is  the  same  as  that  of  the  old  Pharma- 
copoeia. In  the  new  book,  monohydratic  sodium  carbonate  is  used, 
and  this  being  stronger  than  the  hydrous  salt,  a  much  smaller 
quantity  is  taken.  Calx  chlorinata  of  the  present  U.S.P.  is  30  per 
cent,  strength,  while  that  of  the  old  U.S.P.  was  35  per  cent.,  hence 
a  larger  quantity  of  this  compound  is  taken.  The  resulting  product 
contains  0.2  per  cent,  less  of  available  chlorine.    This  compound, 
