'^ApriyimL'''}        Note  on  AmyJo-Nitrous  Ether.  147 
am  I  prepared  to  give  an  opinion  of  the  purity  of  the  few  samples  I 
have  seen.  Since,  however,  its  preparation  is  rather  tedious,  and 
since  it  is  very  apt  to  be  contaminated  with  other  ethers,  the  requi- 
site care  and  precautions  are  probably  not  always  applied. 
Having  had  occasion,  some  time  since,  to  prepare  it  repeatedly  for 
medicinal  purpose,  the  following  remarks  are  offered  as  indicating  a 
way  of  making  nitrite  of  amyl  on  a  convenient  scale.  Mr.  Umney 
prefers  the  process  of  passing  nitrous  (hyponitric)  acid  into  amylic  al- 
cohol. I  regard  this  process  as  unnecessarily  complicated,  since  pu- 
rification by  fractional  distillation  cannot  be  avoided  as  demonstrated 
already  hj  Raeckher.*  According  to  Bunge,t  oz.  amylic  alcohol 
require  from  eight  to  nine  hours,  before  becoming  completely  satu- 
rated with*  nitrous  acid ;  volatile  products  are  given  off,  and  the  residue 
contains  nitrite  and  valerianate  of  amyl  besides  a  black  non-volatile 
body,  crj'Stals  of  nitrate  of  ammonia  and  probably  nitrate  of  amyl. 
The. process,  which  was  first  suggested  in  1844  by  Baiard,  it  seems 
to  me  will  answer  all  requirements,  if  the  observations  of  W.  Hoff- 
mannj  regarding  the  formation  of  nitrate  of  amyl  are  not  disregarded  ; 
ethyl-amylic  ether,  amylic  aldehyde  and  hydrocyanic  acid  are  like- 
wise formed. 
Of  the  three  last  named  compounds,  the  hydrocyanic  acid  is  readily 
removed  from  the  distillate  by  treatment  with  an  alkali,  which  also 
separates  any  nitrous  and  nitric  acid  that  may  have  come  over.  The 
aldehyde  has  its  boiling  point  at  93°  C.  (Kopp)  and  the  ether  above 
110°  C.  These  figures  indicate  the  necessity  of  the  cautels  recom- 
mended by  Baiard,  Hoffmann,  Rieckher,  &c. 
It  is  advisable  to  use  only  rectified  amylic  alcohol,  since  the  pre- 
vious removal  of  ethylic  alcohol  is  much  easier  than  the  removal  of 
the  products  after  the  reaction  with  the  nitric  acid  has  been  com- 
pleted. This  purification  is  most  readily  and  economically  effected 
by  Hirsch's  method,§  with  solution  of  table  salt  and  subsequent  dis- 
tillation with  water. 
The  purified  amylic  alcohol  with  about  an  equal  bulk  of  nitric  acid 
is  introduced  into  a  capacious  glass  retort,  and  a  moderate  heat  is 
applied  and  very  gradually  increased.     As  soon  as  the  mixture  ap- 
*  Jahrb.  f.  pr.  Chem.  xiv,  p.  1. 
t  Krit.  Zeitschr.  ix.  34. 
t  Ann.  Chem.  und  Pharm.  Ixxv,  363. 
^  See  Amer.  Jour.  Pharm.,  1862,  p.  139,  328. 
