386 
Composition  of  Oil  of  Birch. 
f  Am.  Jour.  Pharm, 
t    August.  1883. 
by  distillation.  It  has  a  specific  gravity  of  1-180  at  15°C.  (59°F.), 
and  its  boiling  point  is  constant  at  218°C.  (424-4°F.) 
A  portion  of  the  oil  when  shaken  with  a  concentrated  solution  of 
sodium  bisulphite  afforded  no  crystalline  compound,  thus  proving  the 
absence  of  an  aldehyde. 
The  plan  of  analysis  adopted  was  as  follows : 
To  100  grams  of  the  oil  contained  in  a  half  liter  flask  provided 
with  an  inverted  condenser  a  concentrated  solution  of  50  grams  of 
potassium  hydrate  was  added,  which  is  somewhat  more  than  the  theo- 
retical quantity  required  for  the  decomposition  of  the  oil,  and  the  mix- 
ture boiled  for  six  hours  upon  a  sand-bath.  At  the  end  of  this  time 
the  oil  was  completely  decomposed,  and  a  clear  liquid  was  obtained, 
without  the  separation  of  any  oily  layer,  and  also  affording  none  upon 
dilution  with  water  or  upon  supersaturation  with  an  acid.  This  obser- 
vation demonstrated  conclusively  the  absence  of  a  terpene,  which,  had 
such  been  present,  would  have  remained  undecomposed  by  the  caustic 
alkali,  and  become  separated  at  once  or  upon  subsequent  dilution  of 
the  strongly  alkaline  liquid  with  water.  In  this  manner  400  grams  of 
the  oil  were  treated. 
The  resulting  liquids  were  then  distilled  from  a  sand-bath  until  one- 
fourth  of  the  entire  amount  had  passed  over;  this  distillate  was 
then  redistilled  from  a  sand-bath;  collecting  one-fourth  as  before,  and 
the  latter  distillate,  which  would  contain  all  the  methyl-alcohol,  was 
then  distilled  from  a  water- bath,  and  further  rectified  and  deprived  of 
water  by  distilling  twice  from  quick  lime.  This  liquid  thus  obtained 
then  possessed  the  unmistakable  odor  of  methyl  alcohol,  and  corre- 
sponded to  it  in  its  specific  gravity  and  boiling  point. 
The  liquid  remaining  from  the  first  distillation,  which  would  contain 
the  salicylic  acid  combined  with  the  potassium,  was  then  slightly 
supersaturated  with  hydrochloric  acid,  whereby  a  dense  white  precipi- 
tate of  salicylic  acid  was  obtained.  This  was  then  washed  with  a  little 
water,  dried  by  exposure  to  the  air,  and  purified  by  crystallization 
from  hot  petroleum  benzin,  from  which  it  was  deposited  in  light,  col- 
orless and  lustrous  crystals. 
Upon  adding  a  concentrated  solution  of  potassium  or  sodium  hydrate 
to  the  oil,  as  had  been  previously  observed  by  Procter  {loo.  cit,  1844, 
page  243),  combination  immediately  ensues,  with  liberation  of  heat, 
and  a  white,  crystalline  compound  is  formed,  which  is  decomposed  by 
acids,  with  the  separation  of  the  original  oil. 
