66 
Nitrite  of  A  my  I. 
\  Am.  Jour.  Pharm. 
t      Feb.,  1879. 
However,  two  amylic  alcohols  do  exist  in  the  fusel  oil  of  commerce  : 
one  of  them  is  levogyrate  and  the  other  is  inactive  or  a  mixture  of  levo- 
and  dextrogyrate  alcohols,  almost  impossible  to  separate,  for  their  boil- 
ing points  are  very  nearly  the  same.  If,  however,  the  mixture  be 
treated  with  sulphuric  acid,  two  amylsulphuric  acids  are  obtained,  of 
which  the  barium  salts  present  different  solubilities. 
It  has  long  been  doubtful  whether  these  two  alcohols  were  of  the 
same  or  different  molecular  structure,  but  inasmuch  as  the  active 
alcohol  yields  a  valerianic  acid  of  which  the  quinia  salt  refuses  to 
crystallize,  while  the  quinia  salt  of  the  acid  obtained  from  the  inactive 
alcohol  crystallizes  readily,  it  may  be  fairly  assumed  that  the  difference 
is  dependent  upon  chemical  constitution. 
The  recent  researches  of  J.  A.  Le  Bel1  have  considerably  eluci- 
dated the  subject.  By  subjecting  the  low  residues  obtained  in  the  frac- 
tionation of  propylic  (98°C.)  and  butylic  (ioo,°C.)  alcohols  to  fractional 
distillation  in  a  vacuum,  he  has  succeeded  in  separating  the  two  amylic 
alcohols,  grace  to  the  greater  tension  of  vapor  of  the  inactive  variety. 
Are  we  to  conclude  that  the  difference  in  purity  of  different  samples 
of  nitrite  of  amyl  is  due  to  the  mixture  of  the  two  alcohols  ?  By  no 
means,  for  the  boiling  points  of  the  two  isomeric  nitrites  would  not  be 
widely  separated. 
But,  by  whatever  process  nitrite  of  amyl  be  made,  it  is  quite  possi- 
ble that  its  isomeride  nitropentane  may  be  formed  at  the  same  time, 
and  this  would  raise  the  boiling  point  of  the  product. 
The  amylic  alcohol  which  passes  after  two  or  three  fractionations 
between  128  and  I32°C.  can  be  considered  sufficiently  pure  for  all 
pharmaceutical  preparations,  and  should  the  nitrite  of  amyl  made  from 
it  be  of  poor  quality,  a  faulty  process  or  carelessness  in  the  rectification 
must  have  been  the  cause. 
A  very  fair  yield  of  nitrite  of  amyl  may  be  obtained  by  the  action 
of  potassium  nitrite  and  sulphuric  acid  on  the  alcohol.  The  potassium 
nitrite  may  be  easily  made  by  maintaining  potassium  nitrate  for  some 
time  at  a  dull  red  heat.  It  is  then  heated  with  amylic  alcohol  in  a  flask 
on  a  water  bath,  and  sulphuric  acid,  diluted  with  its  volume  of  water, 
gradually  added.  Nitrite  of  amyl  distils  over  regularly  with  some 
vapor  of   water.     After  washing  the  product  with  a   solution  of 
Comptus  Rendus.    Tome  lxxxvii,  p.  213. 
