April 1, 1.904. J THE TROPICAL AGRICULTURIST. 
665 
The purified oaontchoue from the rubber of the 
yoQDg trees waa very soft aod sticky, whereas that 
furnished by the robber from the older trees exhibited 
very satiafaotory physical properties. 
RE3IN IN THE LATEX DIMiNISHES WITH AOE. 
These tinalysea amply confirm the opinion based 
upon the appearance of the samples, nnd prove that 
the rubber prepared from the latex of the young trees 
of Castilloa elaxdca is a very inferior product, con- 
sisting largely of resin. The results agree with pre- 
vious analyses recorded by different investigators, 
who have invariably found that the amount of resin 
in the latex of Castilloa elastica is very large in the 
young trees, but gradually diminishes with age, 
until after the eighth year or so the tree yields 
robber of good quality. Practical experiments in 
the oaltivation of Castilloa elastica fully support this 
conclusion. The age of the " old trees " under notice 
was not stated, but the amount of resin present 
in the rubber, viz., 15 8 per cent., is much greater 
than is permissible in rubber of good quality. 
Samples of Castilloa rubber, prepared by the Superin- 
tendent of the Royal Botanic Gardens, were for- 
warded to the Imperial Institute for chemical exami- 
nation and commercial valuation by the Government 
of Trinidad. Full particulars regarding the collec- 
tion and preparation of the specimens were furnished 
in a letter from Mr. Hart. These had been pre- 
pared by different methods, and from trees of dif- 
ferent age. 
DESCRIPTION OF THE SAMPLES. 
(a) " 350 c.c. Castilloa latex from trees years 
old. Added 150 c c. alcohol. After coagulation and 
draining the rubber blackened quickly. Obtained 140 
grams of wet rnbber." 
The specimen consisted of a single piece aboat 
4 in. by 2 in. by 1 in. weighing 95 grums, and 
was evidently of very inferior quality. The mass 
was very hard, but could be indented with the finger 
nail and its shape altered by compression; it was 
almost black externally, but dark browu within, and 
small fragments of bark were dibtributed through it. 
Small pieces of the material were soft, and exhibited 
only slight elasticity and very little tenacity. 
(6) " 350 c.c. of Castilloa latex from trees 4J years 
old. Added two litres of water and set to cream 
for 12 hours. Coagulated with alcohol and obtained 
118 grama of wet rubber. This appears brittle. 
Creamed rubber is always cleaner and whiter than 
rubber from latex coagulated as gathered. It appears 
to wash away much proteid matter," 
This was very similar to the preceding sample i^a) 
in appearance and characters, but was a little 
softer and more elastic. It was a single piece 
about 5 in. by 2 in. by 1 in., weighing 85 grams, 
which was dark brown externally, but much lighter 
within, the freahly-cnt surface having a glossy appear- 
ance. 
(c) " 50? c.c. Castilloa latex from trees 4k years 
old. Poured direct on copper mesh (fine wire) and 
allowed to drain. Rnbber coagulated by air naturally 
in 48 hoars. Was taken off wire and doubled up." 
The specimen consisted of a sheet of black rub- 
ber, about 12 in, square and ^ in, thick, which was 
Bligbtly mouldy on the surface. It was of very 
inferior quality, being only slightly elastic, and exhi- 
biting very little tenacity. 
(rf) " 600 CO, of Castilloa latex from trees over 
12 years old. Added alcohol to coagulate. Coagula- 
tion appeared imperfect. To be compared with («) 
old and young," 
This specimen consisted of a single piece of black 
tubber weighing 200 grams. When cut open it was 
foand to be very porous and to contain a consider- 
able quantity of acid liquid ; it was therefore cut 
into slicss and air-dried before analysis. It also con- 
tained nnmerous f>ae;ments of bark and wood of 
. lather large size, \sbich, ou removal, were found to 
ttaouDt to i"i per cent, of the total weight, The 
rubber was very elastic and tenacious, and only slightly 
sticky. 
(e) "Specimen of rnbber made from washed and 
creamed latex of trees 12 years old and over. Coagu- 
lated with alcohol. This appears to be the best speci- 
men of Castilloa sent." 
The sample was a small piece of black rnbber 
weighing 27 grams ; internally it was a dark greyish 
colour thioughout, dry, and quite free from foreign 
matter. The physical characters of the rnbber were 
very satisfactory ; it exhibited considerable elasticity 
and tenacity, and tvas not sticky. In appearance 
and character it wa,3 certainly the best specimen 
of Castilloa rubber submitted. 
CHEMICAL EXAMINATION. 
The following results were obtained on analysis of 
the various samples : — 
SAMPLES AS RECEIVED, 
Variety a Ash in- 
of Rub- Age of Mois- Caout- g ^-^^^ eluded 
ber. Trees, ture. chouc. p3 ' in Dirt. 
Y . Per Per Per Per Per 
lears. ^.^^^^ gg^^^ ceai. cent. cent. 
a Castilloa ih 103 37 1 47-1 5-5 1-47 
b „ 4i 4-3 41-1 53-8 08 0 31 
c ,, 8 0 40 8 45-4 5 8 1 24 
over 
d ,, 12 15-2* 70 1 11-7 3 0t 0-79 
e ., 12 & 2'2 89 1 8-2 0'5 0-25 
over 
CALCULATED FOB DR7 MATERIAL, 
a Castilloa 4^ ,.. 41-3 52 6 6'1 1-64 
b „ 4^ ... 430 56-2 0-8 032, 
c „ 4^ ... 44-4 49-3 63 134 
over 
d „ 12 .,. 82-7 13-8 3 5t 0-93 
e „ 12 & ,.. 91-2 8 3 0 5 0-25, 
over 
It will be seen from these figures that the three 
specimens of Castilloa rubber, Nos. a, h and c, which 
were obtained from trees 4^ years old, contain 
very large amounts of resin, viz., 52'6, 56'2 
and 49'3 per cent, respectively on the dry 
material, and they would, therefure, possess little 
value as rubbers. The results of the chemical 
examination confirm the opinion baaed upon the 
physical characters of the specimens, anJ it is clear 
from these results that Castilloa trees 4i years old 
will not yield a marketable rnbber. Tnis conclu- 
sion agrees with that arrived at by previous investi- 
gators, but it must be remarked that the amount 
of resin present in the specimens under notice, and 
also in the small sample of Castilloa rubber from 
a tree four years old which is already dealt with in 
this report, is considerably greater than has 
been hitherto recorded for Castilloa rubber obtained 
from trees of the same age growing in other conn- 
trie?. Thus Weber in some experiments conducted 
at Las Cascadas on the isthmus of Columbia found 
that the rubber obtained from the trees of 
Castilloa elastica 4 and 5 years old contained 26*47 
and 18 18 per cent, of resin respectively, which is 
about half the amount found in the present case. 
The much higher percentages of resin found in the 
specimens from Trinidad may possibly be due to 
differences of climate, soil, &o. The different me« 
tbods of preparation followed in the three caaea baa 
not influenced the composition of the rubber to 
any appreciable extent, the only striking difference 
being that (b) which was prepared by creaming, 
contained very little foreign matter and ash as com- 
pared with the other two specimens. 
The two samples of Castilloa rubber (c?) and (e) 
which were ohtained from trees 12 years old and 
* These specimens were air-dried before analysis, 
t Exclusive of 4"f} per cent, of back removed before 
analysis, 
