ON  COMMERCIAL  IRON  BY  HYDROGEN. 
23 
as  the  magnetic  oxide  FeO  +  O3,  the  specimens  contain  of  ] 
this  compound  6-3075,  4-024  and  3-77  grs.  consequently  an 
available  amount  of  uncombined  iron  of  3-6925,  5-976  and  6-23 
grs.  These  last  calculations  are  not  quite  exact,  because  the 
sulphur  and  carbon,  although  their  amount  is  small,  ought  to 
have  been  deducted  from  the  oxygen,  whereby  the  magnetic  ox- 
ide would  have  been  lessened  and  the  iron  slightly  increased. 
Taking  everything  together,  No.  2  is  to  be  preferred,  as  yielding 
the  least  odorous  gas  on  dissolving,  and  nearly  the  largest  per- 
centage of  pure  iron. 
But  it  will  be  seen,  that  if  the  above  samples  fairly  represent  j 
the  reduced  iron  in  our  market,  we  are  far  from  having  it  as 
pure  as  it  ought  to  be.  The  sulphur  is  easily  accounted  for  by 
negligent  washing  of  the  precipitated  oxide  o'f  iron  ;  but  where 
does  the  carbon  come  from  ?  Professor  Woehler  states  that  the 
hydrogen  evolved  from  iron  and  sulphuric  acid,  may  be  employ- 
ed for  deoxidation  without  disadvantage,  it  yielding  a  product 
quite  as  pure  as  when  evolved  from  zinc;  the  carbon,  therefore, 
could  scarcely  have  any  other  origin  but  the  dust,  which  cannot 
probably  be  effectually  excluded  from  the  oxide  during  the  pro- 
cess of  washing,  when  made  on  the  large  scale. 
The  presence  of  sulphur,  however,  is  more  objectionable  even 
than  a  small  percentage  of  carbon,  and  the  manufacturers  will 
therefore  have  to  turn  their  attention  to  the  careful  washing  out 
of  the  sulphates,  or  else  prepare  the  oxide  in  a  manner  where 
such  a  contamination  is  impossible. 
In  this  connection,  it  may  be  well  to  again  direct  atten- 
tion to  the  researches  of  Woehler,  as  published  in  the  Amer. 
Jour.  Pharm.  1856,  139.  His  method  for  obtaining  a  pure 
sesquioxide  is  unobjectionable,  at  least  so  far  as  the  result 
is  concerned  :  and  as  the  oxalate  of  iron  yields  pure  iron  in  a 
current  of  hydrogen  at  a  lower  temperature  than  any  other  pre- 
paration, this  may  be  of  special  usefulness.  The  quantity  of  the 
ferrous  oxalate  will  be  increased,  if,  instead  of  oxalic  acid,  the  ox- 
alate of  soda  is  employed  for  precipitation,  but  a  careful  washing 
willthen  be  indispensable.  The  increase  of  cost  by  the  use  of 
oxalic  acid  or  an  oxalate,  I  should  suppose,  ought  to  be  counter- 
balanced by  the  less  trouble  and  the  easier  reduction,  conse- 
quentlyby  a  purer  preparation  and  an  increased  yield. 
Philadelpliia,  Bee.  1860. 
