■^'"'ocTi^^so^'"''}     ^^^y  Ingredients  in  Cod  liver  Oil.  505 
ASHY  INGREDIENTS  IN  Light  Colored  COD  LIVER  OIL. 
By  Professor.  E.  A.  Van  der  Burg. 
In  the  first  part  of  the  Scheikundige  Onderzuckingen,"  by  G.  J. 
Mulder,  Dr.  L.  J.  de  Jongh  says,  on  page  479  of  his  Chemical 
Investigation  of  the  Composition  of  Cod  Liver  Oil":  "-No  less  differ 
the  series  of  inorganic  ingredients  which  we  have  discovered  in  codliver 
oil  from  those  mentioned  by  others."  Further  on,  on  page  480,  line 
10:  ''The  reason  why  Marder,  who,  to  our  knowledge,  has  been  up 
to  the  present  time  the  only  one  that  makes  special  mention  of  the 
inorganic  ingredients  of  the  cod  liver  oil,  has  found  no  phosphoric  acid, 
is  that  he  has  not  tried  to  find  it.  In  declaring  this,  viz.,  the  reasons 
why  the  results  of  our  investigations  on  this  point  differ  from  those  of 
others,  we  believe  we  have  done  no  more  than  our  duty.  If  we  now 
look  on  the  different  results  of  our  own  investigations  of  the  three 
sorts  of  cod  liver  oil  we  may  state  that  the  light-colored  oils  contain 
more  inorganic  ingredients  than  the  dark-colored." 
Dr.  Jongh  also  tells  us  that  his  investigations  led  him  to  the  discov- 
ery that  in  the  former  the  quantity  of  phosphoric  acid  is  nearly  double 
and  that  of  lime  more  than  double  what  is  found  in  the  latter. 
Considering  that  hardly  any  incombustible  matter  is  found  in  the 
light-colored  oil,  it  may  be  of  importance  to  know  how  Dr.  de  Jongh 
got  those  figures. 
To  determine  the  phosphoric  acid  and  the  sulphuric  acid  a  certain 
quantity  of  the  oil  was  saponified  by  the  admixture  of  potassa  caustica. 
The  soap  which  was  obtained  in  this  way  was  decomposed  with  hydro- 
chloric acid.  After  the  removal  of  the  fatty  acids  the  phosphoric  acid 
in  the  filtered  liquor  was  determined  as  phosphas  ferricus  and  the  sul- 
phuric acid  as  sulphas  barycus. 
In  order  to  see  how  much  calcium,  magnesia  and  soda  the  mixture 
contained  a  certain  quantity  of  it  was  carbonized,  the  caibon  digested 
with  hydrochloric  acid,  and  the  phosphoric  acid  removed  from  the  acid 
liquor  as  phosphas  ferri.  After  filtration  the  calcium  was  determined 
as  oxalas  calcis,  and  after  this  had  been  removed  the  magnesia  was  pre- 
cipitated as  phosphas  ammonico-magnesicus.  The  filtrate  was  now 
mixed  with  sulphuric  acid,  evaporated  in  a  platinum  cup,  incinerated 
and  weighed,  and  as  no  potash  was  found  the  weight  was  taken  account 
of  as  sulphas  sodae. 
In  this  manner  the  author  found  in  light-colored  cod  liver  oil  the 
following  percentages  : 
