CHEMICAL  RESEARCHES  ON  AMYLENE. 
409 
obtain  it  from  the  potato  distilleries,  always  contains  ordinary 
oil — to  such  extent,  indeed,  that  it  is  not  rare  to  find  it  in  the 
proportion  of  fifty  per  cent.  The  potato-oil  is,  moreover,  most 
generally  colored,  and  presents  a  burning,  penetrating  and  dis- 
agreeable odor  which  sensibly  diminishes  during  rectification.  It 
is  of  much  importance  to  purify  the  potato-oil,  which  is  used  for 
the  preparation  of  amylene  ;  for  without  this  precaution  the 
chloride  of  zinc,  acting  on  the  ordinary'  alcohol  and  carbonizing 
the  coloring  matter,  develops  an  empyreumatic  product  which 
ought  to  be  avoided  from  the  beginning,  otherwise  thus  taking 
birth,  and  accompanying  the  amylene,  it  cannot  be  separated 
from  it  subsequently. 
M.  Hepp  has  recommended,  following  the  process  of  M. 
Cahours,  to  agitate  the  potato-oil  with  water  in  order  to  remove 
the  alcohol ;  but  if  this  process  has  succeeded  in  the  hands  of 
our  learned  confrere,  it  must  be  owing  to  the  fact  of  his  being 
in  possession  of  almost  pure  amylic  alcohols  ;  for,  if  like  ourself, 
he  had  had  the  misfortune  to  get  hold  of  none  but  highly  alcoholic 
potato-oils,  he  would,  like  us,  have  found  that  the  washings,  while 
carrying  away  the  ordinary  alcohol,  would  likewise  carry  away 
the  fourth,  the  half  and  even  the  whole  of  the  potato-oil.  The 
water  separates  the  alcohol,  it  is  true,  but  the  latter  acquires  im- 
mediately a  great  solvent  power  over  the  potato-oil.  Before  sub- 
mitting it  to  washing,  we  should,  in  all  cases,  look  to  the  quality 
of  the  amylic  alcohol,  and  in  view  to  this  we  here  submit  the 
parallel  of  character  which  we  have  observed  between  the  pure 
and  impure  amylic  alcohols  : 
Qualities  of  pure  Amylic  Alcohol.  Qualities  of  impure  Amylic  Alcohol, 
Potato  oil  is  a  colorless,  limpid  The    crude  potato-oil  is  more 
liquid,  of  an  oily  appearance,  of  a  fluid  and  less  oily  ;  its  odor  is  more 
strong  odor  ;  agreeable  in  its  first  alcoholic  and  stronger,  being  ordi- 
impression,  but  afterwards  nausea-  narily  colored,  and  more  inflamma- 
bund  in  a  high  degree.    When  its  ble  than  the   pure   oil.    When  it 
vapor  is  respired,  asthmatic  symp-  contains  only  one-tenth  of  ordinary 
toms  occur,  which  produce  cough,  alcohol,  and  an  iron  plate  is  moist- 
and  even  vomitings.    Its   taste  is  ened  with  it,  it  burns  when  brought 
very  acid.    It  is  inflammable,  and  into  contact  with  the  flame  of  a 
burns  with  a  whitish  blue  flame.  It  bougie.    The  oil  of  potato  is  very 
boils  at  270°,  and  its  sp.  gr.  is  combustible  ;  but  it  will  not  take  fire 
0.812.  under  such  condition,  from  the  fact 
At  19°  or  20°  it  solidifies,  form-  that  its  volatilization  and  combus- 
