ON  HYDRATED  OXIDE  OF  IRON,  ETC. 
327 
4.  A  minute  quantity  of  a  neutral  salt  added  to  the  concen- 
trated solution  separates  gradually  the  entire  quantity  of  the 
hydrated  ferric  oxide ;  the  same  eifect  is  instantly  produced  by 
diluting  and  boiling  the  mixture. 
5.  Organic  or  mineral  acids  transform  this  modification  of  the 
oxide  into  the  ordinary  kind,  the  solution  becomes  lighter  in 
color,  and  is  then  affected  by  the  usual  reagents. 
6.  Bitter  principles,  like  salicin,  cetrarin,  &c.,  also  digitalin 
and  the  vegetable  alkaloids,  particularly  those  of  morphia,  also 
small  quantities  of  the  volatile  oils,  separate  the  hydrated  oxide 
in  its  soluble  modification. 
By  triturating  the  freshly  precipitated  oxide  in  a  mortar,  to 
promote  the  evaporation  of  the  water,  and  testing  the  solubility 
in  syrup  and  glycerin,  Hornemann  found  that  the  oxide  was 
completely  soluble  therein  when  it  contained  7-2,  7*03,  and  6*6 
equiv.  of  water,  but  did  not  yield  a  clear  solution  when  it  con- 
tained 5'8  equiv.  The  authors  conclude  that  this  soluble  oxide 
of  iron  contains  6  equiv.  of  water  of  hydration. 
Regarding  its  therapeutical  use,  the  authors  state : 
1.  That  it  is  resorbed  is  proven  by  its  secretion  through  the 
kidneys. 
2.  After  its  use  for  several  weeks,  in  the  form  of  syrup  con- 
taining 2  per  cent,  oxide^  or  as  troches,  coating  of  the  tongue, 
blackening  of  the  teeth  and  constipation  are  not  observed ;  the 
preparation  agrees  well  with  chlorotic  women,  weakened  by 
hemorrhage  in  abortion,  with  reconvalescents  and  weak  children  ; 
if  it  should  show  a  tendency  to  diarrhoea,  it  must  be  discontinued 
for  some  days. 
3.  The  preparation  may  be  given  with  fresh  milk  of  an  alka- 
line reaction,  with  arrowroot,  soups  of  mtal  and  extract  of  beef, 
beef  tea,  coffee  and  chocolate,  the  taste  of  which  is  not  affected. 
4.  All  kinds  of  wine  may  serve  as  vehicles  ;  it  may  be  added 
to  the  infusion  of  bitter  remedies  like  gentian,  juglans,  quassia, 
menyanthes  and  Colombo,  or  united  with  their  extracts ;  with 
cinchona  it  can  only  be  given  in  the  forms  of  pills. 
5.  Cold  infusions  of  orange  peel  and  cinnamon  may  serve  as 
vehicles ;  with  other  aromatics  it  can  only  be  given  in  the  form 
of  powder. 
