March 1, 1899.] THE TEOPICAL AGRICULTURIST. 601 
panies formed for rubber-planting, usually fated 
for an eplieiueial esis ence. Tlie tapping is done 
with considerable care by the natives, and even 
should a district become exhauste d, in a few years 
a fresh supply of trees springs up. From the 
planters' point of view Brazil is liardly a suitable 
country, for the cliniate is bad, it is diflicuit 
to obtain labour, and the exchange is liable to 
endless variations. The trees have, hov.-ever, been 
introduced into Ceylon, where small plantations 
exist, and into other colonies*. The method of 
preparing the rubber has been so frequencly des- 
cribed that repetition is needless; but a ''trans- 
lation of a valuable article on rubber of the 
Orinoco " § has received so much attention of late 
that it requires some examination. One of its 
most striking errors is the following: — " As the 
jiiice contains a considerable quantity of water, the 
preparation of rubber consists essentially in 
separating the former from the latter, which is 
perforii.ed by evaporating the water by means 
of a he.iting process or obtaining its coagulaiion 
by ceitain chemical processes. Altliough tlie last 
system is more rapid ihey prefer the former, as 
they pretend that the rubber thus obtained is 
of a superior quality — a supposition devoid of 
all leason." 
As 1 have already had occasion to show,t this 
statement is incorrect, for the heating continues 
for too short a time; (" the rubber" u not'' dried 
in a few minutes ") to evaporate off some 50 per 
cent, of water, and further there is no lois ot 
all reason," for it is a well-known fact that the 
smoked rubber is far preferable to that obtained 
by chemical processes. A comparison of the prices 
of " Park fine'' and " sernaiuby " should be suHi- 
cient proof of this. Why it is so may be made 
clearer from the following experiment. At the 
end of a day's work I had serveral litres of 
latex left, to which an equal volume of water 
had been added, which would not keep over 
night without coagulating. To this a small q^uantity 
of acetic acid was added, and in a short time the 
whole of it had formed a stiff cnrd. On pressing 
and drying, a portion of the water exuded from 
this mass of sernamby, but, it ;.till remained full 
of cavities, and the proteid matter in it quickly 
decomposed, so that ultimately a stinking, inflated 
mass was obtained. 
If this latex had been coagnlated by smoking it 
wouhl have yielded a wet rubber, but the suli- 
seqnent decomposition of protei'is would not have 
set in, for the creosote contained in the smoke 
would have acted as an antiseptic and prevented 
decomposition, as it does when meat is preserved 
by smoking. 
Then ai;ain we lind, " the ruliber thus prepared 
(by smoking) acquires a darkish colour, due to 
the particles of coal which adhere to tlie outer skin. 
■ Some people believe that this tends to inijirove 
it, but such is not the case, for it is thus impreg- 
nated with impurity. ^^'ow when these "bottles" 
of rubl)er are cut across, the fresh, lamiruited 
surfaces are a silvery grey C(dour, and as each 
layer is exposed to the same extent to the action 
of the smoke it is diflicuit to account for the 
outer layers only being so coloured. The freshly 
cut surfaces however soon darken and become 
black in turn, so that the explanation ol oxidation 
seeius far more probable, especially when taken 
in conjunction with the fuct that smoko iswiute§ 
" Kow Bullet i n ,"l8'.'3,iri 5'X 
f'l'rinid.ia HuUftiu," lb93, No. 18, and 1897, p. 36 
J Biffon," Anns. Bot." 18!)S, p.lCu. 
§ " Tiiuidad BullBlin," 1897, p. 36. 
and not black,* for the nuts are simply dry-distilled 
and not actually burnt. If the smoke of these 
heated urncuri nuts is condensed it forms two layers 
of liquid in the receiver, one a clear limpid solution 
consisting mainly of acetic acid, the other, darker 
in colour, of creosote. 
The hot vaiiour of acetic acid brings about 
the coagulation of the pioteids of tiie latex, as 
many easily be proved by direct experiment. 
A solution of alum is said to be in use for 
prei)aring rubber in some parts of the Amazon 
valley. AJorissef states that alum solution has no 
effect upon the latex of Hevea species iiowever. 
The loss in the factories on making up Park 
rubber is as followsj : — (1) Para tine. 10 to 15 per 
cent. ; (2) Entre-tine, the carelessly smoked 
pieces, 15 to 20 per cent.; (3) Sernau.by, rubber 
pulled [from the cuts on tlie tree and cups, 
coagulated by being allowed to stand, d'c, 20 
to 40 per cent. From these data we niay safe y 
conclude that the smoking method of pieparation 
is by far the best in use at present, a view 
which will be further strengtlienen when we coin- 
jiare the losses on making up other sorts of lubber. 
Ceara Rubber xs, the prodnctof Manihot Gluziovii, 
a tree growing chiefly in the highlands of the ytate 
of Ceara, Brazil. Cross is responsil le for most 
of the descriptions of the locality in which it 
irrows, but as his experience of it ;ippears to have 
been limited to Pacatuba, in which place its habitat 
is far from typical, they are not very accurate. 
He records it as giowing at an elevation of 200 
feet above sea level, among granite boulders, in 
a country whose dryness was indicated by the 
fact that "ferns, weeds, grasses, arid mosses" 
were absent. True, it does grow among granite 
boulders, in the scantiest of soil in such localities, 
but it is more at home in the mountains, up to 
a height of 3,600 feet, and even more, where there 
is an abundant rainfall. These facts will serve 
to show the wide range of conditions the tree 
will put ujj with, and were it not for the smallness 
of its yield (1 to 3 lbs per annum) it would he 
in valuable for introducing into many of our 
colonies. Coagulation is brought about either by 
smoking, as on the Amazons, or^by simply allow- 
ing the latex to dry on the tree-trunks or soil. 
The latter methods are objectionable, as the 
rubber invariably contains pieces of bark or grit. 
It may also be prepared by churning the latex, 
and pressing the resulting clots. The method is not 
to be recommended though, for even if the clots 
are cut into thin slices and exposed to the heavy 
pressure of a;mandiocca'press, a considerable jjer- 
centage of water remains in its cavities, and 
decomiiosilion sets in, but not to the same extent 
as in " Ceark scrap." 
Although so imqure it commands a price 
usually second only to "Park fine." The loss is 
from 20 to25 per cent., which, in inferior qualities, 
nniy even amount to 55 per cent. 
Manijabeiia ruhber also comes from T'earii. It 
is the product of //««cor/iia ^pccicva, a ilwarf tree 
with somewhat the iiabit of a birch. The rubber 
is prepared by the addition of an excess of salt 
to the latex, or by Strauss' method of adding 
alum. Even after thirty days' drying in the sun 
it is sjiongy and full of cavities of liquid. As 
might be expected, the loss on purilieation is 
enormous, amounting to fiom 40 to GO per cent. 
* Comn iro the plate on pxRa 757 of the ''Journ. Soo. 
Arts," 1893. 
t "Trinidad BuUelin." 1807, p. 37. 
j"Lo Caoutchouc," Ac, p. 67, 
