AlocSbertPi5M,;m*}      Salicylic  Acid  in  Food  and  Drink.  479 
contents  of  the  beaker  are  then  boiled  for  five  minutes.  The  cloth  is 
then  removed,  washed  in  cold  water,  and  then  boiled  for  five  min- 
utes in  water  which  has  been  very  slightly  acidulated  with  hydro- 
chloric acid. 
If  the  coloring  matter  be  of  fruit  or  vegetable  origin,  the  cloth 
will  either  be  uncolored  or  will  be  changed  to  a  very  faint  pink  or 
brown  tint.  If  coal-tar  or  aniline  colors  have  been  used,  the  cloth 
will  be  dyed  a  bright  pink,  red,  yellow  or  brown,  according  to  the 
color  present.  To  confirm  the  results,  remove  the  cloth  from  the 
acidulated  liquid,  wash  it  well  in  water,  place  it  in  a  beaker  with 
a  little  water  and  add  a  few  drops  of  stronger  ammonia  water.  Veg- 
etable or  fruit  colors  will  not  dissolve,  but  will  change  to  a  green, 
purple  or  yellow  color.  Aniline  or  coal-tar  colors  will  not  be 
changed  in  color,  but  will  be  dissolved,  especially  when  the  solution 
is  heated  to  boiling;  after  which,  upon  the  removal  of  the  cloth, 
acidifying  as  in  the  original  dyeing  test,  inserting  a  fresh  piece  of 
cloth  and  boiling  as  before,  the  color  will  again  be  deposited. 
This  second  dyeing  test  is  considered  an  absolute  proof  of  the  pres- 
ence of  added  coloring  matter,  as  no  fruit  colors  have  yet  been 
found  which  will  be  deposited  upon  the  wool  the  second  time,  while 
aniline  colors  will  always  be  so  deposited. 
When  cochineal  is  present  a  bright  color  is  obtained  with  the  first 
dyeing  which  might  be  mistaken  for  an  aniline  color ;  but  when  the 
ammonia  water  is  added  in  preparing  it  for  the  second  dyeing,  the 
red  color  changes  to  purple,  and  the  second  dyeing  comes  out  prac- 
tically colorless. 
In  testing  for  salicylic  acid,  the  material  is  to  be  prepared  as  in 
testing  for  coloring  matter,  except  that  it  is  to  be  acidulated  with 
sulphuric  acid  instead  of  hydrochloric  acid.  After  acidulating, 
about  50  c.c.  (or  2  fluid  ounces)  of  the  liquid  is  placed  in  a  tall  cyl- 
indrical stoppered  graduate  (a  tall  cylindrical  bottle  will  answer  the 
purpose)  and  a  layer  of  ether  poured  on  the  top  (about  one-fourth 
as  much  ether  as  the  liquid  to  be  extracted).  The  contents  of  the 
cylinder  are  then  mixed  by  inverting  it  a  number  of  times,  taking 
care  not  to  agitate  the  contents  too  violently,  which  would  cause 
the  formation  of  an  emulsion. 
After  complete  separation  of  the  ethereal  layer  has  taken  place, 
about  10  c.c.  (or  2  fluid  drams)  are  cautiously  removed  by  careful 
decantation  or  the  use  of  a  pipette,  transferred  to  a  watch  glass,  and 
the  ether  allowed  to  evaporate  at  a  low  temperature. 
