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 fibre, 
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 r 
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 extremely 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 attributed to the 
exceeding thinness or fluidity both of the Asiatic and African rubber 
latices. Great cart should also be taken in the packing, and lor all 
varieties of gum which are destined to lie for any length of time 
near the points of production 1 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 
