216 
NOTE  ON  COD-LIVER  OIL,  ETC. 
is  again  applied,  and  more  oil  is  obtained.  The  pulpy  matter  is 
then  taken  out  almost  dry.  There  is  a  yet  finer  pulpy  matter, 
which  oozes  through  the  cloth  of  the  press  at  the  bottom  and 
sides." 
The  practical  details  of  "  rendering  "  the  oil,  as  it  is  called, 
involving  the  proper  cooking  "  of  the  livers,  require  some 
skill  and  experience,  so  as  to  separate  it  completely  and  yet  not 
oxidize  or  expose  it  unnecessarily,  so  as  to  induce  acridity  or 
rancidity.  That  the  oil  should  keep  well  it  must  be  entirely 
freed  from  watery  particles  ;  to  be  but  moderately  heated,  and 
the  process  should  be  executed  promptly.  Cod-liver  oil  rapidly 
absorbs  oxygen  from  the  air  if  exposed,  and  always  should  be  en- 
closed in  tight  vessels  immediately  after  its  preparation.  Messrs. 
Marvin  Bros.  &  Bartlett  bottle  all  the  oil  they  make,  and  thus 
secure  it  from  change.  A  sample  of  this  oil  received  with  the 
specimens  was  found  to  be  sweet,  and  free  from  acridity  or  ran- 
cidity, with  the  odor  and  taste  proper  to  this  oil. 
The  pulpy  matter  left  in  the  press  cloth  before  alluded  to,  as 
we  received  it,  was  of  a  soft  cheesey  consistence,  of  a  yellowish- 
salmon  color,  and  possessing  the  odor  of  good  cod-liver  oil ;  but 
on  keeping  it  with  exposure  to  the  air  a  few  days,  it  acquires  a 
rank,  rancid  odor  of  old  cod-liver  oil,  becomes  much  darker  in 
color,  and  contracts  greatly  from  loss  of  moisture.  It  is  strongly 
nitrogenous,  and  when  distilled  with  caustic  potassa  and  chloride 
of  ammonium  it  yields  propylamin  among  other  products.  So 
far  its  only  use  has  been  for  agricultural  purposes,  as  a  manure. 
The  watery  liquid  pressed  from  the  livers  is  presumed  to  be 
the  material  used  in  Paris  to  make  the  extract  of  cod-liver  pills, 
of  which  some  notice  has  been  presented  in  the  Journals.  We 
had  not  time  to  examine  this  before  it  spoiled,  no  means  having 
been  taken  to  preserve  it.  It  was  our  intention  to  examine  it 
'  for  iodine  salts  and  for  propylamin.  If  there  be  any  merit  in 
cod-liver  oil  due  to  iodine  or  bromine,  it  certainly  ought  to  be 
found  in  this  liquid, — yet  it  may  be  questioned  whether  these 
agents  have  anything  to  do  with  the  therapeutic  value  of  this 
popular  remedy. 
