268 
Diffusive  Properties  of  Iron. 
( Am.  Jour.  Pharm. 
)        May,  1880. 
Residue  in  Dialyzer. 
4*86  2-75 
Total,  .  136-82  6i-io 
Loss,       ,      63-18  3-48 
200-00  64-C8 
It  will  be  seen  that  of  the  200  grains  of  the  salt,  containing  64-58 
grains  of  Fe^Og,  put  into  the  dialyzer,  131*96  grains  of  salt,  contain- 
ing 58'35  grains  of  Fe203,  had  diffused  in  twenty-nine  days,  and  that 
there  was  then  a  residue  in  the  dialyzer  amounting  to  4*86  grains  of 
salt,  containing  275  grains  of  Fe203.  There  was  thus  an  apparent 
loss  in  the  process  of  63-18  grains  of  salt,  but  of  only  3*48  grains  of 
FcgOo,  the  latter  no  doubt  partly  arising  from  adhesion  to  the  septum. 
No  entire  cessation  of  diffusion  was  observed. 
The  citrate  of  iron  used  in  the  experiment  was,  as  it  always  is,  acid 
to  test  paper,  and  the  first  two  diffusates  were  so  also,  but  the  third  and 
subsequent  diffusates  were  neutral,  indicating  the  disappearance  of  some 
of  the  acid  radical. 
2.  Ainmonio-c'itrate  of  Iron. — This  salt,  as  met  with  in  commerce, 
usually  contains  about  30  per  cent,  of  peroxide  of  iron,  FcgOg,  but  the 
proportion  varies  in  different  samples.  Several  samples  were  submitted 
to  dialysis. 
(2,  a.) — A  10  per  cent,  solution  of  ammonio-citrate,  containing 
30-21  per  cent,  of  Fe203,  was  dialyzed,  and  the  results  examined  as  in 
the  previous  experiment.  At  the  expiration  of  two  days,  124-59  gf^ins 
or  62-29  P^^'  cent,  of  the  salt  had  diffused,  and  this  contained  27*22 
per  cent,  of  the  FcgOg.  At  the  end  of  another  four  days,  25*79  grains 
more  of  the  salt,  with  32*90  per  cent,  of  Fe^Og,  had  diffused,  making 
the  total  diffusate  in  six  days  150*38  grains,  or  75*19  per  cent,  of  the 
salt  put  into  the  dialyzer,  and  70  per  cent,  of  the  iron  contained  in  the 
salt.  The  diffusion  afterwards  went  on  very  slowly,  yielding  only  3-79 
grains  in  ten  days,  and  at  the  end  of  twenty- two  days  from  the  com- 
mencement, when  the  diffusion  had  nearly  stopped,  the  dialyzer  con- 
tained 20-26  grains  of  a  salt  in  solution,  in  which  the  FegOg  amounted 
to  6i-6i  per  cent. 
(2,  — A  10  per  cent,  solution  of  a  salt  containing  30-9  per  cent. 
3f  Fe203  was  dialyzed  for  two  days.  The  diffusate  gave  108*94  grains, 
or  54'47  per  cent,  of  dried  salt,  containing  27*9  per  cent,  of  Ytf^^. 
In  four  days  more  another  diffusate  was  obtained,  giving  37*36  grains. 
Per  cent.  FeoOg 
in  residue. 
56-65 
