204 
other  places  should  reach  the  European  markets  in  a better  state 
of  preservation.  Most  of  the  localities  of  western  Africa  which 
furnish  rubber,  from  trees  lie  upon  the  coast  and  are  therefore  most 
conveniently  situated  ; the  gum  is  not  allowed  to  remain  long  upon 
the  ground  but  is  promptly  hurried  to  the  seaports  and  shipped  to 
Europe  with  the  utmost  despatch.  Shipments  from  Lagos,  Gold 
Coast,  Senegambia,  and  Sierra  Leone  frequently  reach  Liverpool 
within  50  or  60  days  after  the  sap  from  the  trees  has  been  dried. 
Such  favourable  conditions  are  manifestly  impossible  with  the 
products  from  the  Congo  basin,  and  chiefly  for  the  reason  that  the 
perfect  construction’ of  the  African  respositories  plays  such  an  im- 
portant part  in  the  healthful  preservation  of  our  products.  That 
rubber  should  be  more  or  less  inclined  to  become  viscous  depends 
much  upon  the  method  pursued  in  its  coagulation.  Thus  the 
method  employed  by  the  Bokako  (Bossanga)  furnishes  a gum  of 
greater  resistance,  though  the  process  which  gives  an  extra  dry 
rubber,  exposes  the  product  to  a more  pronounced  as  well  as  rapid 
contamination.  For  example,  let  us  take  a ball  from  Lopori ; 
although  it  is  less  desiccated,  it  resists  the  contaminating  influences 
to  a greater  degree  than  the  well  dried  sheets  from  Kassai.  If  the 
drying  has  been  imperfectly  accomplished  and  the  gum  is  placed  in 
storage  in  such  a manner  as  to  be  deprived  of  the  necessary 
circulation  of  air,  a condition  which  ensues  when  the  balls  are 
packed  too  closely  together,  a sort  of  fermentation  is  set  up  in  the 
interior  of  the  balls  which  in  the  long  run  attacks  the  elastic  flbre, 
and  the  gum  dies,  and  this  is  what  the  English  technically  describe 
as  dead,  perished,  or  flaky  rubber;  it  is  not  viscous  but  pasty.  If, 
however,  reasonable  care  be  taken  in  the  storing  of  the  gum,  even 
watery  or  moist  rubber  will  not  suffer  oxidation.  At  this  point  it 
may  be  well  to  add  that  the  mixing  of  several  varieties  of  latex 
before  coagulation  is  extremel}^  likely  to  induce  organic  decom- 
position ; in  such  cases  the  viscous  character  is  internal  or,  so  to  say, 
inherent.  Happily  such  cases  are  of  rare  occurrence  with  our  rubber 
from  the  Congo. 
The  best  known  preventive  of  oxidation  consists  in  the  drying 
of  the  latex  by  a low  heat,  in  contact  with  the  smoke.  Rubber 
from  Para,  Colombia,  and  Bolivia  is  dried  in  this  way.  It  is 
greatly  to  be  regretted  that  the  milk  of  the  African  rubber  vines 
[Landolphia)  does  not  lend  itself  kindly  to  the  smoke  treatment, 
and,  strange  as  it  may  appear,  even  the  milk  from  the  African  rubber 
trees  is  equally  rebellious  under  this  form  of  treatment.  Some 
samples  of  Kickxia  rubber,  from  the  Gold  Coast,  which  had  been 
dried  in  smoke,  were  critically  examined  by  me,  and  I found  that 
though  the  gum  was  pure  and  of  handsome  appearance,  yet  it  had 
lost  its  elasticity.  This  peculiarity  is  generally  attriliuted  to  the 
exceeding  thinness  or  fluidity  both  of  the  Asiatic  and  African  rubber 
latices.  Great  care  should  also  be  taken  in  the  packing,  and  for  all 
varieties  of  gum  which  are  destined  to  lie  for  any  length  of  time 
near  the  points  of  production  I recommend  that  they  be  put  up  in 
ordinary  sacking,’ and  this  applies  especially  to  those  sorts  which 
have  been  dried  with  extra  care. 
Returning  to  the  subject  of  the  effects  of  the  sun  upon  the  outer 
surfaces  of  the  balls,  I desire  to  state  that  I experimented  upon  some 
