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THE  NEW  RUBBERS. 
The  three  species  of  Manicobar  which  have  been  botanically 
described — Manihot  dichotoma,  M.  piauhyensis,  and  a third  M. 
heptaphylla , seed  of  which  we  have  not  yet  succeeded  in  obtain- 
ing in  Ceylon — occur  wild  in  the  Provinces  of  Bahia  and  Piauhy 
in  Brazil  in  latitudes  ranging  from  8 to  15  degrees  south.  So 
far  much  the  fullest  account  of  these  plants  in  their  native  country 
is  that  given  by  Dr.  Ule  in  the  “Tropenpflanzer”  for  December, 
1907,  a translation  of  which  appeared  in  the  “Tropical  Agri- 
culturist” for  March,  1908.  From  this  account  it  appears  that 
these  species  grow  naturally  in  a much  drier  and  more  mountain- 
ous country  than  the  Para  rubber  ( Hevea  brasiliensis) . 
“Here  Manihot  dichotoma  grows  in  the  true  Catinga  forest, 
and  is  especially  abundant  on  the  mountain  spurs.  The  more 
park-like  regions  where  individual  trees  stand  scattered  is  avoided 
by  M.  dichotoma , which  prefers  a rather  more  thickly  wooded 
country.  It  develops  best  on  a red  loamy  soil,  and  is  less  fre- 
quently to  be  found  on  a sandy  substratum.  Within  a few 
miles  of  Porto  Alegre  on  the  Rio  das  Contas,  a central  station 
for  the  production  of  rubber  from  this  species  of  Manihot,  I 
have  seen  the  mountain  spurs  so  thickly  covered  with  this  tree 
that  it  made  up  almost  half  the  total  forest.”  (Ule.) 
From  an  account  of  the  methods  employed  in  tapping  these 
trees  in  a wild  state,  and  of  the  yield  so  obtainable,  reference  may 
be  made  to  the  above-mentioned  translation  of  Dr.  Ule’s  paper. 
We  are  now  more  directly  concerned  with  the  value  of  Mani- 
cobar rubber  as  a cultivated  product  when  planted  on  estates. 
Dr.  Ule  gives  it  as  his  opinion  that  the  wild  thickets  of  Manihot 
dichotoma  will  very  soon  cease  to  have  any  value  as  a source  of 
rubber.  The  export  of  rubber  from  the  State  of  Bahia  is  said 
to  have  increased  more  than  ten-fold  between  the  years  1900  and 
1906,  that  is  to  say,  from  100  tons  to  over  1,100  tons,  but  very 
little  of  this  was  from  plantations.  Recently,  however,  large 
areas  in  this  district  appear  to  have  been  planted  up  with  these 
Manicobars,  and  from  the  accounts  given  by  Ule  and  others  the 
success  of  these  undertakings  seems  to  be  assured. 
The  following  advantages  are  claimed  by  Messrs.  Vilmorin 
for  the  new  rubbers  as  compared  with  ordinary  Ceara : 
The  latex  is  not  so  thick ; it  coagulates  less  rapidly,  and  is 
therefore  easier  to  deal  with ; it  yields  a rubber  of  much  higher 
quality. 
Secondly,  it  contains  a much  larger  proportion  of  pure  dry 
rubber. 
Lastly,  the  yield  is  greater.  Whereas  the  raw  rubbers  of  Ceara 
and  Piauhy  give  only  60  to  67  per  cent,  of  pure  caoutchouc,  the 
proportion  obtained  from  Manihot  dichotoma  varies  from  70  to 
92  per  cent.  These  figures  do  not,  of  course,  refer  to  planta- 
tion rubbers. — Tropical  Agriculturist,  Colombo. 
