THE TROPICAL AGRICULTURIST. 
[Jan. 1, 19C3. 
time daikeca into a browcish black. This pheno- 
menon, which is at least one of the causes of the 
very bad colour of all the (Jentral American rubbers 
of the present day, in tact, of all the rubbers obtained 
from Castilloa eltstica, I found to be due to the 
presence in the latex of an oxidising ferment (oxydase 
and it is, therefore obvious that in attempting to) 
produce a high-class, pure rubber from Castilloa 
latex the presence of this ferment has to be taken 
into consideration. 
The taste of the Castilloa latex is intensely bitter. 
This appears to be due to the presence in it of a 
Bubstance of the class of bodies chemically described 
aa glucosides. It is this same body which is the 
cause of the intense dark green colouration proiluoed 
by the addition to the 1 itex, or better to its aqueous 
vehicle, of a few drops of a solution of ferric chloride. 
1 presume that th's reaction has been observed 
before, and led the observers to the altogether 
erroneous assumption that the Castilloa latex con- 
tains tannic acid, which latter as is well known, 
produres much the same coloura ion with forric- 
chloride. As a matter of fict, tht-re is not the 
slightest trace of tannic acid to be found in tiiis 
latex, and 1 doubt whether it occurs in the latex 
of any other rubber tree. It is really only necessary 
to state that the latex of Castilloa elastica, beside 
the bodies clceady named, contains a very large 
proportion of albumen, and to remind the reader 
that slbamen may be quantitatively precipitated 
with tannic acid, in order to prove that the pre- 
sence of tannic acid in the latex is an impossibility. 
Indeed, on adding to a solution of the aqueous 
vehicle of the the latex of Castilloa a few drops of 
a dilu e solution of tannic acid, a most copious 
precipitate of albumen tannate is at once obtained. 
Considering that all the different specimens of rub- 
ber latex I have fo far as an opportunity of exam n- 
ing contain albumen in varying qnHntities, though 
none as much as the latex of Cistilloa ela-tica, is 
at the same time sufficient proof of the absence of 
tannic acid in every case. 
A quantitative determination of the amount of 
albumen and albuminous matters in general in the 
latex yielded the rather surprising result that there 
is as much as 11 per cent, of these bodies present. 
Thi?, I believe, is the cause of the extreme etise 
with which the latex of Cat 1 la elastica can be 
cnagulated, I am quite aware that this has been 
attributed to the comparatively large size of the 
rubber globules in the Castilloa Id' et, bui for reason?, 
base! upon evidence, I shall prodi c '. in another paper 
on this important suject, I believe this assumption to 
be erroneous. 
Jn my communication I showed that the latex of 
an 11 year old Castilloa tree contains 31 per cent, 
of pure rubber, and it will, therefore, be seen from 
the above statement regarding the amount of albumin- 
ous matter) in the latex that if we coagulate the 
latter without first removing from it this albuminous 
matter we obtain a rubber containing over 25 per 
cent, of albuminous matter. The native rubber 
collectors prepare the rubbsr from the latex in such 
a way that at least part of the aqueous vehicle of 
the latex is drained away before coagulation tak;3 
place, and consequently we never lind a Central 
American rubber (crude) which contains as much 
as the above stateS quantity (25 per cent, of albumin- 
cua matter), but lots containing from 9 to 13 per 
cent, are quite common. It is, indeed, the presence 
of such a Jarge amount of albuminous matter in the 
Central American and some other Castilloa rubbers 
which is largely responsible for their frequently 
reaching American and European ports in a state 
of pronounced putrid fermentation, of the atrocious 
smell they emit on washing, and of their often 
very unsatisfactory behaviour in the process of 
vulcanisation. When such rubber in a state of ad- 
vanced putrid fermentation is subjected to the wash- 
ing process a very considerable proportion of the 
90»^ulated iilbuwiuous matter, tendered eolubla bj 
the fermentation, is removed, but the rubber, although 
not taking itself an active paic in this fermentation 
is, nevertheless, found to have suffered more or less' 
severely fiom it, to possess little strength, and, after 
vuloanisition, only very moderate distensibility 
(elasticity). If, on the other hand, the rubber 
reaches the factory in fair condition, it contains 
practically the whole of the albuminous matter 
in an insoluble condition and so intimately 
intermixed with the rubber that the washing 
altogether fails to remove more than a mere 
trace of it. We obtain than a washed rubber 
which contains a very 1 rge proportion of albumin- 
ous matter, the presence of which in the washed 
and dried rubber is scarcely noticeable, but which 
is the cause of such rubber forming invaiiably a 
peculiarly "short" and none-resilient vulcanisation 
p.-oduct. It will thus be seen that whatever h:ip- 
pens to such rubber duiing transit it is alway.s 
a very inferior product from what it might be if 
the albuminous matter were kept out of it. In 
fact, I scarcely think 1 want any fur;her justifica- 
tion for the statement that the Castilloa rubber of 
the present day owing to the above discussed 
defect, occupies a much lower position than it would 
hold considering the intrinsic quality of the pure 
rubber it contains. I am, indeed, of the opinion 
that properly prepared Castilloa rubber is superior to 
most of the present day Para grades. 
Incidentally I may remark here that the presence 
of substantial quantities of albuminous matter not 
only in Castilloa rubber, but also in some other 
(African) brands, and the odour they produce owing 
to fermentation has given rise to the now almost 
ineradicable nursery tale that iu certain dis'ricts 
th6 rubber is coagulated by means of one of the 
by-products in the economy of the hu-nan body 
the use of which would be far more commendable on 
account of its inexpensive character than for its 
attractiveness. This fable has never been substan- 
tiated, and I believe that its origin is simply to 
to be found in the offensive urinal smell developed 
on the fermentation of the albuminous matter in 
crude rubber. 
The meihods followed by the native collectors tor 
the coagulation of the Castilloa latex vary con- 
siderably : 
1. The latex is washed with water, but just as 
often this is neglected, and then treated with a 
decoction of the crushed stem of the moon-plant 
Calonyction speciosum. This, according to Dr 
Morris, is the proce.ss practised in British Honduras, 
2. The latex is treated with the juice expressed 
from Ipomoea bona ncx which is stated to be hiehlv 
alkaline. (?) 
3. The latei is collected in shallow holes dug in 
the ground and mixed with a boiling solution of 
soap in water. This process is e.vteusively practised 
in the Isthmus of Panama. 
5. The lattx is treated with a solution of alum . 
Ihese various methods call for the following re- 
marks :— All of them effect the so-called coagulation 
by adding to the latex substances— acids, or alkaliea 
—capable of coagulating the albumen. In other 
words there is no such thing as the coagulation of 
the tndiaruhher itself. What takes place is that 
through the addition to the latex of either an acid, 
or faintly alkaline solution the albumen, of which 
I have shown there is such a large amount in the 
Castilloa latex, is coagulated and carries down 
with it the rubber globules suspended in the latex. 
If the latex is entirely freed from all albuminous 
matter by a carefully conducted series of washings 
it may still be diluted with water, and then forma 
a liquid milky liquid of a some what lighter colour 
than the original latex, but otherwise indistir guisb- 
able from it. But if we now try to coagulate this 
albumin-free liquid with any of the above named 
coagulants we find that the rubber remains quite 
nneffected, no coagulation taking place. Therefore, 
whenever we coagulate the rubber, we c^a onl^ dQ 
