AVugaiPi8f4RM  }      Acids  with  Oil  of  Peppermint.  365 
liquor  was  filtered,  and  a  portion  of  it  agitated  with  fifty  centigrams 
of  oil  of  peppermint  in  a  test-tube.  The  green  color  was  very  evi- 
dent after  twenty-four  hours. 
The  author  has  made  no  experiments  with  beer,  but  he  suggests 
that  it  might  be  tested  by  evaporating  the  suspected  beer  to  the  con- 
sistence of  honey,  treating  the  extract  with  alcohol  to  which  a  few 
drops  of  nitric  acid  have  been  added,  filtering  the  liquid,  concentrat- 
ing and  agitating  with  a  little  oil  of  peppermint.  Nitric  acid  is  used 
for  the  purpose  of  oxidizing  any  acid  that  may  have  been  reduced  to 
picramic  acid  by  the  action  of  sugar  in  the  beer,  and  to  saturate  the 
lime  salts  present. 
Action  of  other  Acids  on  Oil  of  Peppermint. — The  question  as  to 
what  this  coloration  is  due  may  receive  some  elucidation  from  obser- 
vation of  the  action  of  other  acids  upon  oil  of  peppermint,  which  has 
not  yet  been  carefully  studied.  The  following  are  the  principal 
effects  noted  by  the  author  : — 
Sulphuric  Acid  produced  at  first  a  rose  color,  then  reddish-yellow, 
passing  rapidly  to  reddish-brown.  When  ether  was  added  it  acquired 
a  beautiful  yellow  color,  whilst  the  lower  portion  of  the  mixture  was 
colored  red.  When  water  was  added  and  the  mixture  shaken  the 
liquid  separated  into  two  layers,  of  which  the  lower  acid  aqueous 
layer  was  rose-colored,  and  the  uppermost  ethereal  layer  took  a  green- 
ish-blue tint  and  had  a  strong  red  fluorescence. 
Hydrochloric  acid  induced  a  rose  color  rather  slowly.  Upon  the 
addition  of  ether  this  became  faintly  green.  When  water  was  added 
the  underneath  layer  was  rose- colored,  but  the  ether  retained  its  green 
color.    In  some  experiments  a  blue  color  was  produced. 
Nitric  acid  caused  first  a  rose  coloration,  then  red,  soan  becoming 
greenish;  Upon  adding  ether  and  water  and  shaking,  the  underneath 
layer  was  rose,  and  the  ether  rising  to  the  top  took  a  violet-blue  grey 
color. 
The  blue  and  green  tints  were  rapidly  altered  by  the  action  of  air 
and  light. 
These  observations  were  made  upon  pure  and  quite  colorless  oil  of 
peppermint.  When  the  yellow  or  greenish-yellow  tinted  oils  fre- 
quently met  with  in  commerce  were  employed,  the  phenomena  of  col- 
oration were  much  more  intense  with  sulphuric  and  hydrochloric  acids  ; 
whilst  with  nitric  acid  the  ethereal  layer  acquired  a  magnificent  green 
