EXAMINATION  OF  POTATO  AND  RYE  WHISKEY.  573 
EXAMINATION  OF  POTATO  AND  EYE  WHISKEY. 
By  S,  J.  Kappel. 
I.  The  potato  whiskey  was  colorless,  of  the  known  disagreea- 
ble odor,  had  a  faintly  acid  reaction,  and  at  60v  F.  a  specific 
gravity  of  -930  =  53  per  ct.  by  measure  of  absolute  alcohol.  A 
few  drops  of  solution  of  potassa  were  added  to  about  half  an 
ounce  of  the  whiskey,  the  whole  was  evaporated  by  a  moderate 
heat,  and,  after  cooling,  an  excess  of  sulphuric  acid  was  added. 
Immediately  a  cheesy  odor  of  valerianic  acid  was  evolved,  which 
soon  after  gave  place  to  a  persistent  odor  of  fusel  oil. 
The  acid  reaction  of  whiskey  is  usually  attributed  to  the  pre- 
sence of  acetic  acid,  generated  from  the  alcohol  by  oxidation 
from  the  air  during  the  process  of  fermentation ;  the  oxidation 
of  fusel  oil  (amylic  alcohol)  to  valerianic  acid  is  analogous  to 
the  former,  and  might  evidently  take  place  under  similar  cir- 
cumstances.   To  determine  the  quantity  of  acid,  and  whether 
any  was  present  besides  the  valerianic,  1500  grains  of  the 
whiskey  were  digested  with  carbonate  of  baryta  in  excess  until 
the  acid  reaction  had  ceased,  the  filtrate  was  then  decomposed 
by  sulphuric  acid ;  the  precipitate,  after  washing  and  igniting, 
weighed  »7456  grains.     The  filtrate  was   neutralized  with 
potassa,  evaporated  to  a  small  amount,  then  distilled  with  an 
excess  of  sulphuric  acid ;  the  distillate  had  the  odor  of  pure  va- 
lerianic acid;  it  was  nearly  neutralized  with  potassa,  and  slowly 
evaporated  to  dryness.    The  saline  residue  had  the  sweet  taste 
of  the  alkaline  valerianates,  and  on  decomposition  by  sulphuric 
acid,  a  pure  valerianic  odor  without  any  acetic  smell  was  given 
off.     The  acid  of  the  whiskey,  therefore,  is  valerianic  acid  only, 
and  from  the  sulphate  of  baryta  (equivalents  116.7)  the  quanti- 
ty of  valerianic  acid  (C10  H9  03  ==  93)  is  calculated  116.7  :  93= 
•7456  :  -595  grains,  which  in  100  parts  of  whiskey  corresponds 
with  »0397  per  ct.  of  valerianic  acid. 
By  evaporation,  ignition,  treating  with  nitric  acid,  ammonia 
and  potassa  successively,  copper  was  detected,  yielding  «00184 
per  cent,  oxide  of  copper. 
II.  The  rye  whiskey  was  slightly  yellowish,  acid  and  con- 
tained 52  per  ct.  absolute  alcohol.  Treated  as  above,  no  acetic, 
but  .03125  per  ct.  valerianic  acid  was  detected.  The  small  quan- 
