Am.  Jour.  Pharrn. 
April,  1894. 
Salicylic  Acid  in  Food. 
195 
phuric  acid  and  the  mixture  subjected  to  distillation,  the  distillate 
being  collected  in  fifty  cc.  portions.  The  first  portion  is  thrown 
away  and  the  acid  estimated  in  the  next  two  colorimetrically.  The 
quantity  found  is  multiplied  by  eight,  it  being  assumed  that  one- 
eighth  of  the  total  salicylic  acid  will  come  over  in  those  two  fractions 
when  using  the  amounts  of  liquid  specified. 
All  the  samples  of  canned  vegetables  were  examined  in  this  way, 
using  the  fresh  contents  of  the  cans.  Afterwards,  for  various 
reasons,  I  had  the  whole  series  gone  over  again  and  the  extraction 
done  in  a  different  fashion.  The  residual  contents  of  the  cans  had 
in  the  meantime  been  dried  and  ground  to  a  powder  capable  of 
going  through  a  hundred  mesh  sieve.  Portions  of  this  powder 
were  made  into  a  paste,  or  rather  a  very  stiff  dough,  with  dilute 
sulphuric  acid,  and  the  product  placed  in  an  ordinary  ether 
extraction  apparatus  where  it  was  extracted  with  ether  for  several 
hours.  When  the  ether  extract  was  evaporated  to  dryness,  and  the 
residue  taken  up  with  water  and  distilled,  the  distillate  gave  the 
salicylic  acid  reaction  with  much  greater  brilliancy  than  had  the 
original  test,  and  many  samples  were  found  to  contain  the  acid 
which  had  before  given  only  doubtful  tests  or  none  at  all  in  some 
cases.  The  cause  of  this  difference  was  no  doubt  the  imperfect 
extraction  in  the  first  method  of  separation,  which  practically  gave 
only  the  salicylic  acid  present  in  the  juice,  while  the  latter  method 
gave  that  existing  in  the  solid  portions  as  well.  Many  reactions 
were  quite  faint,  so  much  so  as  to  raise  the  question  of  the  purpose 
of  the  addition  of  such  minute  quantities  of  salicylic  acid.  The 
smallness  of  these  quantities  was  probably  due,  however,  to  a  cause 
first  pointed  out  by  Kolbe  in  1880.  Kolbe  found  that  salicylic  acid 
completely  disappeared  from  wine  and  from  water  preserved  in 
casks,  while  in  similar  samples  preserved  in  glass  this  disappearance 
did  not  take  place.  Four  months'  standing,  in  some  cases,  were 
sufficient  to  cause  this  disappearance.  As  an  experiment,  he  placed 
thoroughly  washed  cubes  of  different  woods  in  glass  flasks  in  con- 
tact with  different  solutions  of  salicylic  acid  and  found  that  they 
caused  a  complete  disappearance  of  the  acid  after  various  periods  of 
time,  while  control  samples  in  which  no  wood  was  placed  retained 
their  full  content  of  salicylic  acid.  From  the  results  of  this  work 
he  drew  the  inference  that  woody  tissue  not  only  removed  the  sali- 
cylic acid  from  solution  but  caused  its  total  destruction  in  some 
way,  since  he  could  not  recover  it  from  the  cubes  of  woods  used  in 
