554  New  Method  of  Detecting  Alcohol.     { Am^C;  *£m- 
cation  of  my  molybdenum  test  for  alcohol  to  the  detection  of  that  sub- 
stance when  used  for  such  adulteration,  and  finding  that  it  might  be 
usefully  employed  for  this  purpose,  I  brought  the  matter  under  the 
notice  of  the  Pharmaceutical  Society  of  Ireland,  at  its  meeting  in  last 
April.  A  number  of  circumstances,  however,  prevented  me  from 
publishing  before  this  my  communication  on  that  subject. 
Having  briefly  described  the  molybdenum  test  for  alcohol,  which 
was  published  last  year  in  the  "  Pharmaceutical  Journal,"  "  Chemical 
News/'  and  in  other  scientific  periodicals,  I  pointed  out  how  it  afforded 
a  very  ready  means  for  the  detection  of  alcohol  in  the  essential  or  vola- 
tile oils,  it  being  only  necessary  to  agitate  a  little  of  the  oil  under  exam- 
ination with  a  small  quantity  of  distilled  water,  and  having  allowed  the 
mixture  to  stand  for  a  short  time  till  the  oil  and  water  have  again  sepa- 
rated, to  take  a  drop  or  two  of  the  watery  portion  and  add  to  it  three 
or  four  drops  of  a  solution  of  molybdic  acid  in  strong  sulphuric  acid, 
when  the  characteristic  blue  reaction  will  appear  if  alcohol  be  present. 
The  following  very  simple  way  I  adopted  in  applying  this  test  to  the 
essential  oils  :  A  glass  tube  of  about  four  inches  in  length. and  of  about 
a  quarter  of  an  inch  in  diameter  in  its  internal  bore  was  taken,  one  end 
of  which  being  heated  was  drawn  out  to  a  point,  and  closed  so  as  still 
to  leave  a  very  small  hole,  whilst  the  edges  of  the  other  end  were 
merely  rounded  by  fusion,1  and  to  this  latter  was  adapted  a  sound,  well- 
fitting  cork,  ors  better  still,  an  India  rubber  stopper,  capable  of  closing 
the  aperture  perfectly  air  tight.  The  small  hole  being  closed  by  one 
of  the  fingers  placed  firmly  against  it,  the  tube  is  filled  to  about  one- 
third2  of  its  contents  with  distilled  water,  and  then  about  an  equal  vol- 
ume of  the  essential  oil  added.  The  larger  end  of  the  tube  is  now  to 
be  tightly  closed  with  the  cork  or  stopper,  the  finger  being  still  kept 
1  Several  tubes  suitable  for  this  purpose  may  be  easily  made  by  selecting  a  tube  of 
rather  soft  glass,  not  too  thin  in  its  substance  and  of  about  the  bore  stated,  and  hav- 
ing with  a  spirit  lamp  or  by  means  of  gas  drawn  it  out  to  a  fine  bore  at  intervals  of 
about  eight  or  nine  inches  apart,  the  tube  is  cut  with  a  file,  both  at  the  centres  of 
contraction  and  of  the  intervals  between  them,  and  finally  the  edges  of  the  larger 
end  of  each  tube  rounded  and  of  the  smaller  one  closed  to  a  fine  point  by  fusion. 
2  In  cases  where  the  degree  of  adulteration  may  be  small,  it  will  be  well  to  dimi- 
nish the  proportion  of  the  water  employed  so  as  not  to  dilute  the  adulterant  too 
much;  and  where  the  very  expensive  oils  are  the  subject  of  examination,  smaller 
sized  tubes  than  those  recommended  may  be  employed. 
