10 
an  invention  “for  the  rapid  coagulation  of  fresh  latex  from  rubber 
“ trees.  ” A few  words  explaining  my  method  may  perhaps  be  of 
interest  to  the  readers  of  the  Bulletin. 
So  far  we  know  of  3 modes  of  coagulation. 
1.  Spontaneous  coagulation  such  as  takes  place  on  the  tree 
from  the  heat  of  day,  producing  scrap. 
2.  Coagulation  by  chemicals. 
3.  Coagulation  by  artificial  dry  heat  such  as  that  employed  by 
the  Amazon  native. 
I make  no  mention  just  now  of  coagulation  by  formaldehyde 
recently  preconised  by  Dr.  Weber,  to  which  Mr.  PEARS  has  lately 
drawn  the  attention  of  planters;  nor  of  coagulation  by  centrifugal 
action.  I shall  come  to  them  presently. 
Spontaneous  coagulation  is  uncertain,  unclean  and  wasteful ; 
decomposition  is  liable  to  occur  in  the  milk  if  exposed  in  any  quan^ 
tity,  especially  that  of  Hevea  which  is  apt  to  turn  putrid  in  a few 
hours. 
Coagulation  by  chemicals  is  a handy,  clean  and  expeditious  way 
of  preparing  rubber,  but  we  cannot  blind  ourselves  to  the  fact  that 
it  has  not  yet  established  its  efficiency  to  the  satisfaction  of  the 
rubber  trade.  There  is  a keen  suspicion  abroad  that,  as  Dr. 
Weber  says  “ coagulation  of  rubber  by  acids  results  in  differentia^ 
“ting  it  more  or  less  from  the  original  product”  and  I believe  it  is 
a fact  that  its  behaviour  in  the  manufactured  state  does  not  tend  to 
give  it  a good  name.  If  that  is  so,  why,  the  treatment  of  rubber 
latex  by  acids  must  go  to  the  wall. 
We  have  to  consider  now  the  third  method,  viz.  coagulation  by 
artificial  dry  heat  as  employed  by  the  Amazon  natives.  The  method 
is  so  well  known  that  there  is  no  need  to  describe  it  here,  but  it 
will  be  well  to  settle  one  point  in  connection  with  it,  i.e.,  the  precise 
action  of  the  smoke  on  the  latex. 
It  was  thought  at  one  time  that  the  smoke  of  the  nuts  often  used 
by  the  natives  had  a strange  and  peculiar  property  of  coagulating 
the  milk  independently  of  the  heat  evolved;  but  this  is  not  so.  As 
consul  Temple  says  : “ It  is  a mistake  to  suppose  that  all,  or,  even 
“ a large  proportion  of  the  rubber  coming  from  the  Amazon  is  cured 
“in  this  way  (with  the  nuts).  It  is  on  the  contrary  very  rarely 
“ that  the  rubber  cutter  will  be  at  the  trouble  to  collect  these  nuts  ; 
“he  nearly  always  prefers  to  use  wood  chips  which  give  him  less 
“ trouble  to  procure.  ” 
We  may  infer  from  this  that  any  white  smoke  developing  suf- 
ficient heat,  and  not  actually  deleterious,  will  do  for  the  purpose  ; 
and  further  that  the  smoke  coagulates  not  because  of  any  virtue  of 
the  nuts  or  of  the  material  employed,  but  simply  because  it  is  hot, 
just  as  spontaneous  coagulation  is  brought  about  by  the  heat  of 
day.  The  native  employs  smoke  in  preference  to  an  open  fire  be- 
cause of  the  risk  of  burning  the  rubber,  a frequent  occurrence  even 
in  the  case  of  smoke  coagulation.  The  smoke  has,  moreover, 
antiseptic  qualities,  but,  as  a set-off  against  this,  the  particles  of 
soot  which  it  contains,  constitute  in  themselves  an  impurity.  I 
think  the  main  secret  of  the  success  of  the  Para  method  is  this  ; 
