ON  OLEUM  ARACHIS  HYPOGiEiE. 
298 
both  in  the  East  and  West  Indies.  At  all  events  it  is  extensive- 
ly cultivated  in  tropical  countries  as  well  as  in  the  southern  part 
of  the  United  States,  and  will  even  grow  in  this  latitude.  It 
seems  to  prefer  a  sandy  soil,  and  in  favorable  localities  is  a 
very  prolific  bearer. 
The  plant  above  described  yields  what  are  known  to  us  as 
ground  nuts  or  pea  nuts.  These  nuts  contain  besides  emulsin 
and  other  matter,  from  20  to  25  per  cent,  of  a  fixed  oil.  In 
the  preparation  of  the  oil,  the  nuts  including  the  external  shells 
which  are  necessary  in  order  to  prevent  the  mass  from  caking, 
are  ground  under  heavy  chasing  stones,  of  about  seven  feet  in 
diameter,  and  after  remaining  there  for  half  an  hour,  the  pulp 
is  heated  in  order  to  facilitate  the  operation  ;  the  whole  is  then 
submitted  to  a  pressure  of  about  forty  tons  to  the  square  inch, 
and  yields  the  oil  upon  expression.  The  nuts  are  imported  for 
the  purpose,  direct  to  this  city,  from  Sierra  Leone,  Goree  and 
Gambia,  on  the  western  coast  of  Africa.  The  Gambia  nuts  are 
of  a  superior  quality,  but  as  the  other  varieties  yield  quite  as 
good  an  oil,  they  are  used  by  the  manufacturer  in  preference  to 
the  more  expensive  ones.  In  order  to  ascertain  the  exact  pro- 
portion of  oil  contained  in  the  nuts,  one  thousand  grains  de- 
prived of  the  outer  shells  were  bruised  and  exhausted  with  ether, 
and  yielded  260  grains  of  oil,  or  in  the  proportion  of  26  per 
cent. 
Pea  nut  oil,  known  in  commerce  by  the  simple  name  of  nut  oily 
is  of  a  bright  yellow  color,  rather  darker  than  the  oil  of 
sweet  almonds  ;  it  has  a  mild  and  not  unpleasant  taste,  and  the 
characteristic  odor  of  the  nuts.  A  portion  of  the  nuts  deprived 
of  their  cuticle,  yielded  an  oil  almost  entirely  colorless,  but  in 
no  other  respect  superior  to  the  commercial  variety.  The  oil  is 
soluble  in  all  proportions  in  ether,  chloroform  and  benzine,  and 
is  insoluble  in  alcohol  and  acetone.  Nitric  acid  first  blackens 
and  then  reddens  it,  and  sulphuric  acid,  by  acting  upon  the  or- 
ganic matter,  thickens  it  and  produces  a  deep  red  color.  It  has 
a  specific  gravity  of  0-918  at  60°  F.  and  placed  in  a  mixture  of 
salt  and  ice,  it  was  found  to  thicken  at  38°,  and  congeals  into 
an  imperfectly  homogeneous  mass  at  the  freezing  point  of 
water.  Heated  to  a  temperature  of  580°  F.  the  mercury 
remains  stationary  for  a  short  time,  and  then  rises  suddenly  ; 
