410  CHEMICAL  RESEARCHES  ON  AMYLENE. 
tion  demand  a  higher  degree  of  heat 
than  can  be  imparted  to  it  in  an  in- 
stant on  the  conducting  metal. 
Pouring  a  little  of  thia  product 
in  a  glass  tube  containing  water, 
and  reversing  the  tube,  after  hav- 
ing corked  it,  the  crude  oil  changes 
the  water,  in  traversing  it  becomes 
opalescent,  and  communicates  to  it 
a  milky  appearance  ;  and  if  the  ex- 
periment be  conducted  in  a  gradu- 
ated tube,  and  the  mixture  be 
strongly  agitated,  after  repose  it 
will  be  observed  that  the  superin- 
cumbent oil  is  diminished  in  quan- 
tity, correspondingly  with  the 
amount  of  alcohol  which  has  been 
dissolved. 
When  it  contains  alcohol,  the 
latter  is  naturally  accompanied 
with  water ;  but  the  mixture  is 
rapidly  warmed,  when  a  salt  which 
has  a  strong  attraction  for  water  is 
introduced,  as  the  dry  chlorides  of 
zinc  and  calcium. 
Purification  of  Potato- Oil. 
We  must  look  to  the  method  which  possesses  the  greatest  effi- 
cacy, and  which  is  at  the  same  time  the  least  expensive.  After 
various  trials,  the  method  of  purification  which  has  been  attended 
with  the  best  success  in  our  hands,  is  the  following :  I  pour  the 
amylic  alcohol  in  the  cucurbit  of  an  alembic,  and  adding  four  or 
five  times  its  volume  of  water,  I  agitate  the  mixture,  and  luting 
the  apparatus,  I  distil  with  a  very  moderate  heat.  At  first,  the 
resulting  product  is  a  limpid  and  homogeneous  product,  odor 
strongly  alcoholic,  and  miscible  with  water  without  turbidity.  Up 
to  this  the  product  appears  to  be  ordinary  alcohol,  but  soon  the 
distillation  slackens",  and  then  the  first  product  must  be  removed., 
and  the  recipient  must  be  changed.  At  this  second  step,  the 
distilled  liquor  is  milky,  which  is  a  mixture  of  ordinary  alcohol, 
amylic  alcohol,  and  water ;  then  comes  the  amylic  alcohol  almost 
pure,  accompanied  with  water  only  ;  and  finally,  the  distillation 
is  to  be  arrested,  when  it  is  found  that  nothing  passes  over  but 
ing  crystalline  scales.  It  stains  pa- 
per, the  stains  disappearing  some 
time  after.  It  is  sparingly  soluble 
in  water,  to  which  it  imparts  its 
odor.  It  mixes  in  all  proportions 
with  alcohol,  and  ether  and  the 
fatty  and  the  essential  oils,  etc. 
(Liebig). 
We  may  add  that  in  agitating 
this  pure  oil  with  water  in  a  wide 
tube,  it  arises  again  to  the  top,  and 
occupies  the  same  space  in  the  tube 
that  it  occupied  at  first.  In  the  ex- 
periment, the  potato-oil  ought  to 
retain  its  transparency,  and  the 
water  itself  ought  to  remain  limpid. 
When  an  iron  blade,  moistened 
with  it,  is  brought  near  the  flame  of 
a  bougie,  the  metal,  receiving  apart 
of  the  heat,  leaves  no  trace  of  the 
amylic  alcohol.  In  order  to  inflame, 
under  these  circumstances,  the  potato 
oil  must  be  at  39°  to  40°  of  the 
aerometer.  This  test  is  of  value  only 
in  the  absence  of  ordinary  alcohol. 
