404  Oils  of  Wintergreen  and  Birch.  {Amkl°^^m' 
The  sample  examined  by  us  had  a  boiling  point  of  217°  C,  and  a 
specific  gravity  of  1*1833  at  15°  C.  Immediately  on  the  addition  of 
potassium  hydrate  the  characteristic  wintergreen  odor  disappeared, 
and  a  disagreeable  phenol-like  odor  was  noticed.  Petroleum  ether 
removed  nothing  from  this  alkaline  solution.  On  adding  chemically 
pure  hydrochloric  acid  a  very  bulky  precipitate  separated.  This  was 
collected,  pressed,  purified  and  dried  as  in  the  case  of  the  acids  from 
the  oils,  when  it  was  found  to  be  about  four  times  as  Iftilky  as  they. 
In  weight,  however,  it  was  the  same.  Its  melting  point  was  150°  C. 
Pure  salicylic  acid  melts  at  156°  C.  The  powdered  acid  was  heated 
with  petroleum  ether  and  the  solution,  after  removing  the  first  crop 
of  crystals,  was  allowed  to  evaporate  spontaneously. 
The  residue  from  this  evaporation  was  much  larger  than  that  ob- 
tained from  the  oils,  and,  after  purification  was  found  to  melt  at  122° 
C.  or  only  six- tenths  of  a  degree  above  benzoic  acid.  The  crystals 
gave  off  the  characteristic  odor  of  benzoic  acid  when  warmed  and 
when  dissolved  in  hot  water,  and  otherwise  corresponded  with  that 
acid. 
0*1012  gram  substance  gave  0*2548  C02  and  0*0443  H20. 
Calculated  for 
Found.  Benzoic  Acid. 
C,  68*67  per  cent.  68*85  per  cent. 
H,  4*87       "  4*92 
O,  26*46      i(  26*23  " 
100*00  100*00 
Vapor  Density. — 0*062  gram  substance  displaced  12*5  cc.  air. 
Found  4*29 
Calculated  for  Benzoic  Acid  4*23 
Both  the  combustion  and  the  vapor  density  determination  were  re- 
peated without  important  variation.  We  made  no  exact  determina- 
tion of  the  proportion  of  benzoic  acid  present,  but  it  was  not  far  from 
15  per  cent,  of  the  total  acid  precipitated.  In  the  acid  precipitated 
from  the  oils  it  was  not  more  than  1  per  cent.  Great  loss  necessarily 
occurred  in  the  process  of  purification. 
SUMMARY. 
I.  Previous  investigators  have  found  oil  of  wintergreen  to  consist 
of  methyl  salicylate  and  a  hydrocarbon,  called  gaultherilene;  and  oil 
of  birch  to  be  composed  of  methyl  salicylate  alone. 
