37 2  The  International  Exposition. 
to  whom,  likewise,  the  credit  is  due  of  having  proven  the  very  rapid  development, 
even  on  dry  snd  exposed  spots,  of  Euc.  globulus,  Labill.,  Euc.  obliqua,  L'Herit.,  and' 
other  Australian  trees  ("  Am.  Jour.  Pharm.,"  1868,  p.  51),  upon  which  quality  the 
malaria-destroying  properties  of  the  blue  gum  tree  (Euc.  globulus)  appear  to 
depend.  It  is,  however,  not  unlikely  that  the  presence  of  a  large  proportion  of 
volatile  oil  may  be  quite  an  important  factor  in  this  respect. 
Volatile  oils  are  found  in  all  the  eucalypts,  whether  they  merely  attain  the 
moderate  size  of  shrubs,  like  the  mallee  scrub  [Euc.  dumosa,  Cunn.,  E.  oleosa  and 
socialis,  Muel.),  or  rise  as  towering  giants  to  the  height  of  400  or  500  feet,  like  the 
Euc.  colossea,  Muel.,  and  Euc.  amygdalina,  Labill.  The  vast  amount  of  volatile  oil 
produced  by  the  Australian  eucalypts  has  been  well  set  forth  in  a  paper  read  by 
Mr.  Jos.  Bosisto,  President  of  the  Pharmaceutical  Society  of  Victoria,  before  the 
Royal  Society  of  Victoria,  August  10,  1874,  from  which  we  make  the  following 
abstract  : 
The  eucalypts  agree  in  this,  that  they  cast  their  bark  ;  that  the  leaves  are  ever- 
green and  have  translucent  oil  cells  ;  that  the  petiole  is  half  twisted  and  the  plane 
of  the  leaf  parallel  to  the  axis  of  the  tree  ;  that  the  roots  are  dispersive  and  drain 
water  largely  from  the  soil,  and  that  they  contain  tannin  (tannate  gum  resin),, 
volatile  acid  and  volatile  oil.  Most  parts  of  the  tree  contain  the  two  first  men- 
tioned principles,  but  the  oil  is  found  only  in  the  leaves.  Regarding  the  quantity 
of  the  volatile  oil  yielded  by  the  eucalypts,  the  following  8  out  of  130  species 
enumerated  by  Baron  Mueller  are  regarded  as  representative,  and  1,000  lbs.  of 
their  fresh  leaves  (attached  to  very  small  branches)  yield  the  quantities  of  volatile 
oil  stated  below : 
1  Euc.  odorata,  Behr,  or  peppermint  tree,         yield     7  fluidounces  volatile  oil.. 
2  Euc.  viminalis,  Labill.,  or  manna  gum, 
3  Euc.  rostrata,  Schlech.,  or  red  gum, 
4  Euc.  obliqua,  L'Her.,  or  stringy  bark, 
5  Euc.  globulus,  Labill.,  or  blue  gum, 
6  Euc.  sideroxylon,  Bent.,  or  iron  bark, 
7  Euc.  oleosa,  Muel.,  or  mallee, 
8  Euc.  amygdalina,  Labill.,  or  peppermint  tree, 
The  range  of  the  species  represented  by  the  first  two  is  limited,  while  the  others 
have  a  wide  range.  The  supply  of  oil  varies,  the  variation,  however,  does  not 
arise  from  any  diminution  of  leaves,  nor  does  it  follow  in  a  cycle  of  time  from 
maximum  to  mimimum,  but  it  is  intermittent.  The  full  causes  of  these  peculiari- 
ties are  not  known  ;  but  some  are  pointed  out  as  follows  : 
Euc.  amygdalina,  which  varies  in  size  from  that  of  an  ordinary  willow  to  over 
350  feet  in  height,  occupies  chiefly  the  higher  portions  of  undulating  forest  lands 
and  the  sides  of  the  ranges,  and  does  not  extend  over  100  miles  inland  5  the  ground 
where  it  grows  retains  a  little  moisture  throughout  the  summer  months,  September 
to  April,  the  roots  run  chiefly  lateral  and  are  seldom  lower  than  three  feet  from  the 
surface ;  they  are  surrounded  with  a  soil  evenly  cool,  but  the  temperature  of  the 
air  has  its  usual  summer  range,  and  during  these  months  the  supply  of  oil  from 
week  to  week  is  very  even  ;  but  as  the  cooler  or  winter  months  approach,  the 
/Am.  Jour.  Phariru 
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