'''"•  ■^Txs^so!'"' }  Analysis  of  Iodine-Iron  Codliver  Oil.  507 
Oct. 
This  weight  multiplied  by  0*7  gives  the  quantity  of  iron  in  the  oil.  If 
the  oil  is  of  the  right  kind  there  should  be  0*27  per  cent,  of  iron.  One 
has  to  be  very  careful  in  burning  the  oil,  as  it  is  very  combustible,  and 
the  experiment  consequently  liable  to  fail. 
The  vessel — I  always  use  one  of  platinum — should  be  filled  for  no 
more  than  one-sixth.  It  should  be  heated  by  a  gas  flame  under  the 
chimney.  The  oil  will  be  observed  to  lose  the  violet  color  and  become 
brownish-red.  As  soon  as  the  color  of  the  oil  has  changed  in  this  way, 
there  will  be  a  sufficient  quantity  of  combustible  vapor,  that  may  be 
ignited  by  a  flame,  and  will  keep  burning  for  some  time.  At  that 
moment  the  gas  flame  should  be  removed,  and  the  combustion,  that 
heretofore  took  place  in  a  very  great  flame,  will  keep  on  quietly.  As 
soon  as  the  flame  is  extinguished,  the  vessel  should  be  heated  anew,  and 
again  some  inflammable  vapors  will  appear.  When  the  oil  is  com- 
pletely carbonized,  a  beginnino;  should  be  made  with  a  total  combus- 
tion of  the  carbon.  This  last  process  may  be  quickened  a  good  deal, 
if  every  now  and  then  a  drop  of  water  is  poured  on  the  cooled  carbon, 
and  after  a  slow  and  careful  evaporation  of  the  water  the  carbon  is 
ignited  afresh.  The  red  ash  may  be  determined  as  pure  iron  oxide. 
Should  further  proof  be  wanted,  the  ash  may  be  dissolved  in  hydro- 
chloric acid,  reduced  by  zinc,  after  which  the  iron  may  be  easily 
determined  by  the  ordinary  titrated  solution  of  potassium  permanga- 
nate. 
To  find  out  the  iodine,  5  grams  of  the  oil  is  sufficient.  This  should 
be  saponified  with  an  alcoholic  solution  of  potash  (which  must  contain 
no  iodine,  of  course),  by  heating  it  for  an  hour  or  two,  in  a  porcelain 
cup  on  a  water-bath.  After  this  the  soap  must  be  completely  carbon- 
ized in  the  same  cup  by  careful  heating,  and  the  carbon  treated  with 
water,  until  it  ceases  to  have  an  alkaline  reaction.  As  a  test  that  the 
combustion  has  taken  place  in  the  right  manner,  the  solution  must  be 
totally  colorless.  The  clear  liquid  must  be  rendered  a  little  acid  by 
admixture  of  hydrochloric  acid  and  precipitated  by  a  solution  of  palla- 
dium. The  precipitate  may  be  weighed  now,  or  as  palladium  metal, 
after  heating.  If  the  preparation  has  been  of  the  right  composition,, 
5  grams  will  produce  about  0'o87  gram  of  iodetum  palladiosum,  or 
about  0-025  of  palladium. — Ibid. 
