WOOD  SPIRIT  AND  ITS  DETECTION. 
157 
relations  of  this  peculiar  compound,  and  likewise  enables  me  to 
point  out  how  this  particular  reaction  may  be  made  available 
for  the  detection  of  "  methylated  spirits." 
Detection  of  Wood  Spirit.— It  is  a  well-known  fact  that 
the  liquid  sold  under  the  name  of  «  methylated  spirits"  is  a 
mixture  of  ten  per  cent,  wood-naphtha,  and  ninety  of  spirit  of 
wine.  The  addition  of  the  former  communicates  a  very  disa- 
greeable taste  and  odor  to  the  latter,  thus  rendering  it  unpota- 
ble,  and,  it  is  said,  unfit  for  internal  use.  This  mixed  spirit, 
though  easily  recognized  by  its  odor  when  alone,  yet,  if  used  in 
the  preparation  of  many  strong-smelling  tinctures  or  essences, 
cannot  be  thus  detected,  and  we  are  then  obliged  to  resort  to 
chemicil  means  to  aid  us  in  the  discovery  of  the  adulteration. 
Up  to  the  present  time,  but  one  test  has  been  proposed  for  the 
detection  of  wood-spirit ;  this  is  generally  known  as  "  Ure's 
test,"  having  been  first  mentioned  by  the  eminent  chemist  of 
that  name.  This  test  simply  consists  in  adding  powdered  hy- 
drate of  potash  to  the  suspected  liquid  ;  if  wood-spirit  be  pres- 
ent, the  mixture  becomes  brown  in  about  half  an  hour.  That 
this  is  a  simple,  easy,  and  correct  test  when  the  spirit  is  un- 
mixed with  vegetable  principles,  I  do  not  deny ;  but  there  is 
one  serious  source  of  error,  which,  I  think,  prevents  it  from 
being  generally  applicable  to  the  detection  of  wood-spirit  in 
alcoholic  tinctures,  and  this  I  will  now  endeavor  to  make  evident. 
In  commencing  the  examination  of  a  sample  of  any  tincture,  it 
is,  of  course,  necessary  to  distil  it,  and  apply  the  test  to  the 
distillate.  We  all  know  that  most  tinctures  contain  some  vol- 
atile principles  extracted  from  the  plants  used  in  their  prepara- 
tion •  when  these  are  distilled,  the  volatile  oil,  though  generally 
of  a  high  boiling-point,  is  dissolved  in  the  vapor  of  the  spirit, 
and  thus  contaminates  even  the  first  portions  of  the  distillate. 
If  to  this  we  add  caustic  potash  in  powder,  in  many  cases  the 
liquid  will  assume  a  brown  tint,  even  though  wood-spirit  is  not 
present,  owing  to  the  well-known  action  of  the  alkali  on  many 
essential  oils — thus  indicating  an  adulteration  which  did  not 
really  exist. 
The  method  which  I  adopt  in  testing  for  wood-spirit  is  as 
follows  : — A  small  quantity  of  the  suspected  spirit  is  placed  in 
a  tube  retort,  and  distilled  over  into  a  cooled  test-tube ;  two  or 
