402  Oils  of  Wintergreen  and  Birch.  {AmA.lglllFm9m' 
muslin  strainer,  washed  with  a  little  cold  water,  pressed,  washed, 
pressed  again  and  recrystallized  from  boiling  water.  The  washings 
were  concentrated,  the  acid  as  far  as  possible  recovered,  purified, 
mixed  with  the  pressed  lot  and  the  whole  dried  at  60°  C. 
The  dry  mass  was  pulverized  to  reduce  its  bulk  and  then  macerated 
successively  with  three  portions  of  petroleum  ether.  The  latter  was 
partly  recovered  by  distillation  and  the  residue  allowed  to  stand  and 
become  cool,  when  a  crop  of  crystals  of  salicylic  acid  separated. 
After  removing  these  the  liquid  was  allowed  to  evaporate  sponta- 
neously ;  the  crystalline  residue  from  the  evaporation,  although  small 
in  amount,  was  purified  by  crystallizing  several  times  from  boiling 
water  and  petroleum  ether,  when  the  crystals  became  pearly  in  char- 
acter, and  gave  the  odor  of  benzoic  acid  when  dissolved  in  boiling 
water.  On  the  addition  of  ferric  chloride  solution  only  faint  evidence 
of  salicylic  acid  was  obtained.  The  crystals  from  oil  of  wintergreen 
by  this  process  melted  at  125°  C,  and  those  similarly  obtained  from 
oil  of  birch  melted  at  124°  C.  It  may  be  recalled  that  benzoic  acid 
melts  at  121-4°  C. 
The  crystals  from  oil  of  wintergreen  yielded  the  following  results 
on  combustion : 
0-0712  gram  substance  gave  0-1771  C02  and  0-0311  H20. 
Calculated  for  Calculated  for 
Found.  Benzoic  Acid.  Salicylic  Acid. 
C,       67-84  per  cent.       68*85  per  cent.      60*87  per  cent. 
H,        4*85     "  4*92     "  4*34  " 
O,       27*31     «  26*^3     "  34-79  " 
100-00  100-00  100-00 
Vapor  Density. — 0*0671  gram  substance  displaced  13*3  cc.  air. 
Found  4*36 
Calculated  for  Benzoic  Acid  4*23 
"         "  Salicylic  Acid  4*78 
The  crystals  similarly  obtained  from  oil  of  birch  gave  on  combus- 
tion the  following  results: 
0-0812  gram  substance  gave  0-2035  C02  and  0*035  H20. 
C,  68*35  per  cent. 
H,   4*79  " 
O,  26*86  " 
100-00 
