556  New  Method  of  Detecting  Alcohol.     { AmN^u,rl8p7h7arm- 
The  experiments  I  have  made  on  a  number  of  the  essential  oils,1 
which  were  apparently  pure,  or  at  least  were  unadulterated  with  alco- 
hol, show  that  if  they  are  agitated  with  distilled  water,  and  after  they 
have  again  separated  from  it  a  drop  or  two  of  the  watery  portion  be 
taken  and  tested  in  the  manner  already  described,  there  will  either  be 
no  change  of  color  observable,  or,  what  is  more  frequently  the  case, 
there  will  be  a  faint  light-brown  or  yellowish-brown  tint  produced,  or 
lastly,  in  some  few  instances  a  light  olive  or  grey  is  developed,  quickly 
changing  to  the  former  tints,  all  of  which  soon  fade  away,  leaving  the 
mixtures  colorless  or  very  nearly  so.  But  if  the  oil  is  adulterated  with 
alcohol,  the  water  dissolving  out  that  substance,  a  drop  or  two  of  the 
aqueous  portion  develops  with  the  test  solution,  after  a  few  moments, 
the  deep  azure-blue  coloration  which  is  so  characteristic  of  that  sub- 
stance, and  this  is  much  more  permanent,  generally  speaking,  than  the 
shades  of  color  caused  by  the  essential  oils  alone  when  so  treated, 
though  even  this,  as  in  their  case,  will  fade  away,  leaving  the  mixture 
colorless,  or  very  nearly  so,  after  a  shorter  or  longer  exposure  to  the 
air.  If  the  amount  of  alcohol  present  be  considerable  the  blue  effect 
will  be  produced  after  a  few  moments,  even  at  the  ordinary  tempera- 
ture, but  where  the  quantity  is  very  small  I  have  found  that  the  appli- 
cation of  a  very  gentle  heat  renders  the  test  far  more  sensitive. 
As,  however,  I  have  ascertained  that  a  heat  of  21 2°  Fahrenheit, 
and  in  some  cases  a  temperature  even  considerably  below  that  point, 
especially  if  continued  for  some  time,  will  develop  a  more  or  less  blue 
coloration  with  the  water  which  has  been  agitated  along  with  essential 
oils  apparently  pure,  when  it  reacts  on  the  molybdic  solution,  some 
caution  must  be  observed  in  the  application  of  heat. 
It  appears,  however,  from  my  experiments  with  the  essential  oils  I 
have  operated  on,  that  the  water  so  treated  and  then  allowed  to  sepa- 
rate from  them,  as  in  this  method  of  testing,  might  be  heated  with  the 
molybdic  solution  to  120°  Fahr.  on  a  water-bath,  without  developing 
a  blue  coloration,  at  least,  unless  that  heat  is  continued  for  a  consider- 
able time,  though  such  a  comparatively  low  degree  of  heat  is  quite 
1  The  following  were  the  essential  oils  experimented  on  :  otto  of  roses,  rose  gera- 
nium, neroli,  neroli  petit  grain,  santal  wood,  rhodium,  patchouly,  bergamot,  ver- 
bena, lavender,  rosemary,  cinnamon,  bitter  almonds,  lemon,  bitter  orange,  cloves, 
caraway,  peppermint,  nutmeg,  mustard,  anise,  fennel,  cajaput,  cubebs,  juniper,  tur- 
pentine. 
