182 
Eucalyptus  Products. 
J  Am.  Jour.  Pharm. 
X      April,  1886. 
cording  to  the  time  of  year  at  which  the  leaves  are  distilled.  E.  oleosa 
gives  at  one  time  only  2  pints,  and  at  others  as  much  as  1  gallon  of 
volatile  oil  per  ton  of  leaves.  In  summer,  when  the  soil  is  hard  and 
dry,  it  yields  but  little  oil;  but  in  winter,  when  the  moistened  earth 
permits  of  more  vigorous  vegetation  and  development,  the  percentage 
of  oil  is  much  larger.  The  contrary  is  the  case  with  E.  amygdalina, 
which  grows  in  upland  districts,  and  which  consequently  has  its  vege- 
tation checked  by  the  greater  cold  in  winter,  and  therefore  yields  oil 
most  abundantly  in  the  summer.  The  eucalyptus  oil  of  commerce,  as 
pointed  out  by  Mr.  MacEwan  and  others,  has  hitherto  consisted  chiefly 
of  the  oils  of  E.  amygdalina  and  E..  dumosa.  The  former  lends  itself 
well  to  the  dilution  of  the  more  valuable  essential  oils,  such  as  neroli, 
rose,  etc.,  for  use  in  perfuming  soaps,  etc.  The  latter  finds  its  princi- 
pal use  in  the  manufacture  of  varnishes,  a  comparatively  small  pro- 
portion being  used  in  medicine.  This  will  be  readily  understood  from 
the  fact  that  in  Mr.  Bosisto's  manufactory  alone  at  least  six  tons  of 
leaves  are  operated  on  daily,  and  the  annual  production  is  not  less 
than  12,000  lbs.  of  the  oil. 
The  solvent  powers  of  eucalyptus  oil  on  resins,  etc.,  have  been  given 
in  the  following  order:  mastic,  sandarac,  elemi,  xanthorrhea,  resin, 
benzoin,  copal,  amber,  anime,  shellac,  caoutchouc,  and  guttapercha. 
The  oil  added  to  methylated  spirit,  in  the  proportion  10  ounces  of 
the  former  to  1  gallon  of  the  latter,  is  used  to  dissolve  kauri  resin, 
which  will  dissolve  in  this  mixture  without  the  aid  of  heat,  to  the  ex- 
tent of  2  lbs.  out  of  every  2  J  lbs.  used :  the  addition  of  a  little  colo- 
phony or  Venice  turpentine  rendering  the  kauri  resin  completely  solu- 
ble. It  is  also  used  to  dissolve  asphaltum  for  photograph  varnish. 
In  veterinary  practice  it  is  used  in-  Australia  as  an  embrocation  for 
swellings,  bruises  or  stiff  joints.  In  domestic  practice  it  is  employed 
for  rheumatism,  etc. 
The  necessity  for  manufacturing  the  oil  cheaply  as  a  commercial 
product  has  naturally  led  to  the  choice  of  the  two  species  mentioned, 
which  as  will  be  seen  from  the  above  table,  yield  a  much  larger  quantity 
than  E.  globulus.  The  two  other  species  which  yield  more  oil  than 
the  latter,  viz. :  E.  leucoxylon  and  E.  goniocalyx,  being  probably  more 
scattered  in  mode  of  growth,  would  be  less  easily  procurable. 
The  oil  which  passes  in  commerce  under  the  name  of  oil  of  E.  du- 
mosa1 is  likely  to  vary  considerably  in  specific  gravity  and  in  charac- 
1  E.  dumosa  is  considered  to  be  a  small  form  of  E  incrassata. 
