56  ON  THE  RANCIDITY  OF  FATS. 
tion,  and  of  whose  valuable  labors  I  have  freely  availed  myself. 
There  can  be  no  question  of  the  presence  of  water  in  all  neu- 
tral fats ;  albuminous  matter  in  some  form  may  also  be  safely 
assumed  to  be  in  company  with  it.  It  is  often  met  with  in  a  floc- 
culent  form  at  the  bottom  of  jars  of  olive  oil,  and  cannot  fail 
to  be  present  in  all  fats  of  animal  origin,  whilst  MM.  Saussure 
and  Pelouze  have  noted  the  absorption  of  oxygen  during  the 
drying  of  siccative  oils,  some  of  which  in  return  evolve  hydro- 
gen and  carbonic  acid.  I  have  myself  observed  a  candle  low- 
ered into  a  jar  partly  filled  with  cod-liver  oil,  that  had  remained 
some  time  in  contact  with  the  air  in  the  upper  part  of  the  ves- 
sel, suddenly  extinguished.  It  is  doubtless  true,  on  the  suppo- 
sition of  a  ferment  being  the  agent  that  effects  the  disturbance, 
that  the  removal  of  any  one  of  the  essential  conditions  would 
prevent  its  action.  But  can  it  be  done  in  a  practical  way  ?  I 
believe  not.  To  remove  the  last  trace  of  humidity  would  be 
impossible,  except  by  tedious  and  expensive  methods.  Still,  a 
partial  drying  is  better  than  none,  and  the  experience  of  house- 
wives is  unanimous  on  the  point  as  regards  the  melting  of  lard, 
which  they  say  will  not  keep  unless  it  has  been  made  to  boil. 
Albumen  has  been  sought  to  be  removed  by  agitation  with  sul- 
phuric acid  of  40°  Beaume',  washing  with  water  and  subse- 
quently drying.  The  process  was  employed  some  years  ago  in 
preparing  rape  oil  for  burning  in  light-houses,  and  was  found 
to  hinder  its  oxidation.  I  have  not  been  able  to  imagine  an 
easy  process  for  freeing  oils,  etc.,  of  this  dangerous  ingredient, 
and  have,  therefore,  made  no  experiments  in  that  direction. 
M.  Pelouze  made  many  attempts  to  insulate  the  body,  but 
failed.  Nevertheless  he  was  able  from  its  effects  to  identify  it 
as  one  of  the  albuminous  series.  I  shall  be  able  to  show,  fur- 
ther on,  that  its  activity  may  be  effectually  neutralized  by  a 
simple  method.  The  entire  exclusion  of  air  is  of  course  prac- 
tically impossible. 
The  length  of  time  required  for  the  development  of  these 
changes  makes  experimenting  very  tedious,  and  renders  one 
unable  to  do  so  much  in  a  given  time  as  one  could  wish.  I 
have,  therefore,  confined  myself  within  very  narrow  limits,  re- 
lating to  practical  remedies  only,  and  to  lard  as  the  base  of 
experiment. 
