160  ON  WOOD  OIL,  A  SUBSTITUTE  FOR  COPAIBA. 
Islands,  on  account  of  its  yielding  a  thin  liquid  balsam,  commonly  called 
Wood  Oil,  which  is  much  used  in  painting  ships,  houses,  &c. 
"  To  procure  the  balsam,  a  large  notch  is  cut  into  the  trunk  of  the  tree, 
near  the  earth,  (say  about  30  inches  from  the  ground),  -where  a  fire  is 
kept  up  until  the  wound  is  charred,  soon  after  which  the  liquid  begins  to 
ooze  out,  A  small  gutter  is  cut  in  the  wood  to  conduct  the  liquid  into  a 
vessel  placed  to  receive  it.  The  average  produce  of  the  best  trees  during 
the  season,  is  said  to  be  sometimes  40  gallons.  It  is  found  necessary, 
every  3  or  4  weeks,  to  cut  off  the  old  charred  surfaces  and  burn  it  afresh  ; 
in  large  healthy  trees  abounding  in  balsam,  they  even  cut  a  second  notch 
in  some  other  part  of  the  tree,  and  char  it  as  the  first. 
"  These  operations  are  performed  during  the  months  of  November,  De- 
cember;  January  and  February.  Should  any  of  the  trees  appear  sickly 
the  following  season,  one  or  more  years'  respite  is  given  them." 
The  same  author  also  states  that  Wood  Oil  is  afforded  by  D. 
costatus  i'D.  angustifolius  W.  et  A.),  D.  alatus  Roxb.  and  D. 
incanus  Roxb.,  the  last  mentioned  being  reputed  to  furnish  the 
largest  proportion  of  the  best  sort. 
Closely  allied  to  the  Wood  Oil  of  Dipterocarpus  is  the  oleo- 
resin  termed  CampJior  Oil,  produced  by  Dryobalanops  Oamphora 
Colebr.,  a  tree  of  the  same  natural  order.  For  a  specimen  of 
this  oleo-resin  and  of  an  analogous  liquid  called  Lagam  Oil,  both 
brought  from  Sumatra  by  Dr.  Junghuhn,  I  am  indebted  to  the 
courtesy  of  Dr.  J.  E.  De  Vrij  of  Rotterdam. 
Wood  Oil,  as  imported  from  Moulmein,  is,  after  filtration,  a 
transparent  dark  brown  liquid,  of  somewhat  greater  consistence 
than  Olive  Oil,  sp.  gr.  of  -964  and  an  odor  and  taste  like  co- 
paiba, though  perhaps  hardly  so  strong.  One  part  of  it  treated 
with  two  parts  of  alcohol  sp.  gr.  -796,  is  dissolved,  with  the  ex- 
ception of  a  minute  quantity  of  darkish  flocculent  matter,  which 
subsides  upon  repose. 
But  its  most  curious  property  (as  noticed  by  Mr.  Charles 
Lowe  with  reference  to  a  liquid  which  I  suppose  to  have  been 
Wood  Oil*)  is  that  exhibited  when  it  is  heated  in  a  corked  vial 
to  about  266°  F.  (130°  C.f).  Thus  treated  it  becomes  slightly 
turbid,  and  so  gelatinous  that  the  vial  may  be  inverted,  even 
*  On  a  new  variety  of  Balsam  of  Copaiba — Pharmaceutical  Journal,  vol. 
xiv.  pp.  65,  66. 
f  Mr.  Lowe  says  230°  F.,  but  a  much  more  striking  effect  is  produced 
on  the  Wood  Oil  by  the  temperature  I  have  named. 
