292 [November, 1902.] 
IMPERIAL INSTITUTE JOURNAL. 
Vol. VIII. No. 95. 
continues, while the mines are only partially working, distress is certain to be 
occasioned. 
The Committee of the Chamber of Mines, the Committee of Consulting 
Engineers, and the Association of Mine Managers have prepared an important 
report on the labour question. They state that they have considered pro- 
posals regarding Canadian, Australian, Italian, Cypriot and Tunisian labour, 
and are of opinion that there would be no advantage in dealing with them 
at present. Three courses are open, they continue, to restore industry to the 
position it occupied before the war, namely, white unskilled labour in part as 
a substitution for native labour, an adequate supply of native labour, and 
imported coloured labour. They consider the success of the proposal regard- 
ing white labour impossible as a practical solution of the difficulty. Regarding 
the payment of natives, it is pointed out that the old “ boys,” who attained a 
considerable degree of skill, will not return unless they are paid higher wages, 
and it is further pointed out that other conditions exist which render it 
necessary to make wages more attractive. It recommends that the recruiting 
of unskilled labourers be confined to Africa, that the organisation of the 
Native Labour Association be strengthened, and that the pay of natives be 
increased, but so regulated that their average earnings do not exceed 50s. 
either for piece or day work. This computation is based on the average earn- 
ings of natives before the war. The adoption of the recommendations is 
contingent upon the present arrangements of the Native Labour Association 
for the recruiting and distribution of natives being rigidly adhered to. 
The annual report on the Federated Malay States contains many 
references to labour difficulties. The cost of living — food, wages, etc. — and 
of mining has so greatly increased of late years, while the exchange value of 
the dollar has decreased, that, with tin at, say $60 a picul of 133! lb., a con- 
siderable number of existing mines would be compelled to shut down or work 
without profit, until the rates of wages re-adjusted themselves. At Selangor, 
the Acting Secretary for Chinese Affairs reported that the miners had a bad 
year, owing to the claims for wages from coolies and disputes, which exceeded 
those of all former years. He attributed the cause chiefly to the scarcity and 
dearness of labour. There has been a falling off in the supply of Indian 
labour. Of the icpoo tickets for passengers from India to the colony and 
Federated Malay States which the Government guarantee annually, only 
7,243 were taken up. This is partly attributed to the improved conditions of 
life of the coolie in India, and partly to the more stringent compulsory 
medical examination of intending emigrants from Negapatam. It has been 
necessary to increase the rate of wages offered by Government, and it is pro- 
posed to raise the minimum rate of wages of statute immigrants fixed by law. 
Foreign Countries. — In France the trouble in the coal-mining 
industry again broke out. The men demanded that the question of the 
superannuation fund should be settled without delay, and that the eight- 
hours working day arrangement should be extended. They also required 
the wages question gone into, and demanded a settlement on a number of 
minor points; such as the representation of the miners on the board of 
inspectors. The strikers obtained for a time the co-operation of the dockers 
at Dunkirk and Marseilles, who decided not to unload any British coal until 
the miners’ demands were satisfied. This step was not very successful. A 
movement on the part of some extremists in the Belgian coal trade to take 
advantage of the situation by bringing about a general strike, was checked 
by the council of the Miners’ Federation. Considerable unrest, however, still 
prevails. The coal strikes in the United States, after lasting 23 weeks 
and causing, it is estimated, a general loss of $140,000,000, was terminated 
by the mediation of President Roosevelt. • That the end came none too 
soon is evidenced by the fact that the weekly normal output of 1,300,000 tons 
decreased to about 98,000 tons. The President did not ask for any state- 
ment of claim, but appealed to the men’s patriotism to avert the national 
catastrophe which a winter coal famine would bring about. He also promised 
to appoint a commission to investigate thoroughly the matters at issue. After 
prolonged conferences the constitution of this commission was agreed upon. 
In a series ol articles in the Moscow News, the writer shows by means 
of figures that not only Russian capital, but even Russian labour in the 
Russian naphtha-bearing regions, is being gradually ousted by British and other 
foreign labour. He shows, inter alia , that while the percentage of Russian 
hands employed at the Caucasian and other wells has fallen considerably 
during a recent period of 12 months, the percentage of the foreigners, for 
the most part British, has risen during the same period from 17*9 to 217 
per cent. He adds that at the present moment the efflux of Russian 
labourers from the Russian oil-bearing regions has swollen to such an extent 
that it has become nothing more or less than an emigration en masse, and he 
accuses the Russian authorities, not only of apathy in the matter, but of 
open administrative approval. He quotes Russian official statistics as 
proving that, during the nine months ending February of the present year, 
no less than 8,500 Russian hands, with their families, were deported out of 
Baku alone in consequence of the immigration into that town of British 
and other foreign workmen. The correspondent of The Times adds, by way 
of comment, that, though foreign labour is undoubtedly increasing at the 
Russian oil-wells and manufactories in Baku and the Caucasus generally, the 
writer apparently overlooks the fact that the Russian oil industry has of late 
suffered considerably from unfair competition, low prices, and other causes 
whose operation is likely to be only temporary. The recent depression has 
naturally resulted in the discharge of many men, and one explanation of the 
difference in the proportion of Russian to foreign discharged hands is to be 
found in the fact that the foreigner is, as a rule, a skilled workman and 
imported on a contract, while the bulk of Russian labour at the wells and 
factories is dischargeable at comparatively short notice. 
SCIENTIFIC AND TECHNICAL DEPARTMENT 
• OF THE IMPERIAL INSTITUTE. 
H 
EXPERIMENTS ON THE LATEX AND RUBBER FROM 
CASTILLOA ELASTICA . 
There are many important problems in connection with the extraction of the latex from 
rubber trees and its conversion into rubber which require careful investigation by scientific 
observers, and considerable interest, therefore, attaches to a series of articles contributed by 
Dr. C. O. Weber, a well-known rubber expert, to The India-rubber and Gutta-percha 
Traded Journal (Vol. xxiv., Nos. 6, 7, 8), giving an account of some experiments which 
he conducted while on a visit to the rubber plantation of the Las Cascadas Plantations Com- 
pany on the Isthmus of Panama. 
The plantation is situated in the hilly district near the town of Panama, where the land 
rises very gradually to a height of 1,200 feet or more, and, at the lower altitudes, is eminently 
suited for the cultivation of rubber, cacao and coffee. The Central American rubber tree, 
a variety of Castilloa , is the one cultivated, and, at the present time, the plantation contains 
70,000 of these trees, of which 15,000 are from eleven to twelve years old. An exact 
botanical identification of the tree was difficult, since at the time of the visit neither flowers 
nor fruit were present, but, from a close study of the morphological characters, Dr. Weber 
concludes that it is almost certainly the true Castilloa elastica. Very discrepant accounts are 
given by different observers as to the quantity of rubber which can be obtained from a 
Castilloa tree, figures ranging from 2 to 49 lb., or even more, being quoted as the yield 
from trees growing in Central America, while, on the other hand, experiments conducted 
by Dr. Trimen in Ceylon upon a large number of trees gave a maximum yield of only 
4*3 oz. The yield of rubber from the trees at Las Cascadas was as follows : — 
Age of tree. 
Yield of latex. 
Percentage of rubber 
in latex. 
Yield of rubber. 
6 years . 
. I lb. 13 oz. 
. 26 
. 7 '5 oz. 
7 it • 
. 2 lb. 5 oz. 
. 26 
. 9*6 oz. 
s ,, 
. 3 lb. I oz. 
. 29 
. 14*2 oz. 
n „ 
. 5 lb. 3 oz. 
31 
. 25*7 oz. 
The yields from the trees of eight and eleven years of age represent the means of a 
number of experiments, while the figures for the younger trees are the means of two trials ; 
the results were considered to be rather below than above the average. The trees can be 
tapped with perfect safety twice a year, so that the annual yield of rubber would be twice 
that given in the above table. There is little doubt that the amount of rubber yielded by tbe 
same tree in different districts is liable to considerable variation, and the need for careful 
experiments before the cultivation of any particular variety is undertaken upon a large scale 
cannot be too strongly emphasised. 
The yield of rubber is, of course, intimately associated with the amount of latex 
furnished by the tree, and many experiments have been made from time to time to determine 
the best method of making the incisions in order to secure the maximum quantity of the 
latter. The point to be aimed at in the tapping process is to obtain as large a supply of 
latex as possible without in any way injuring the vigour and growth of the tree. It is clear 
that the best method of making the incisions will depend largely upon the distribution and 
arrangement of the laticiferous tissue, and, as the latter may vary widely, it is impossible to 
lay down any universal rule ; the method of tapping must be adapted to suit the particular 
conditions. The laticiferous vessels in rubber trees are usually stated to lie in the layers of 
bast immediately beneath the bark, without extending into the wood, but Dr. Weber found 
that in Castilloa, although the bulk of the vessels were thus situarted, there were also a number 
of large ducts distributed through the wood, and a considerable number surrounding the pith 
in the centre. Whether these inner vessels communicate at all with the outer ones was not 
investigated at the moment, since, in any case, only the external vessels lying in the bast can 
be opened without risk of seriously injuring the tree. In the bast the vessels were found to 
run longitudinally, and there was surprisingly little evidence of any lateral intercommunication 
between them. This observation at once explained the fact that longitudinal incisions in the 
bark gave either an extremely small flow of latex, or, in many cases, none at all, and 
suggested that horizontal cuts would yield the best result. In the case of Castilloa, however, 
a horizontal cut is not very satisfactory for the collection of the exuding latex, and, in 
addition, a large number of such cuts require to be made in order to extract the whole of the 
available latex, so that it was found preferable to employ a continuous spiral cut which can be 
made to drain practically the whole of the trunk. A spiral incision of this kind, made at an 
angle of not more than 45 degrees, gives an excellent result as far as the flow of latex is 
concerned, and is much better than the system of making a series of V-shaped cuts connected 
by a single vertical one. 
The method of making the incisions is of some importance, since if they are carried too 
deep there is danger of inflicting permanent injury upon the tree, though Dr. Weber, as the 
result of his observations, expresses the opinion that cuts penetrating to the wood are not 
necessarily injurious to the tree, but may retard the healing process. With a view to 
preventing the attacks of insects on the exposed surfaces, the wounds were treated with an 
antiseptic paint, and it was found that this materially assisted the healing, as in these cases 
the cuts began to close up a week after the tapping. A new kind of tool, enabling a clean 
and continuous cut to be made, was also introduced with very satisfactory results, and 
particulars of this are promised in a later communication. 
The latex obtained from Castilloa elastica at Las Cascadas does not flow like milk, but 
issues from the cuts in the form of a thick cream containing a very high percentage of rubber. 
This point again illustrates the variation shown by the same tree growing in different districts, 
for while a similar latex is yielded by Castilloa elastica in some parts of Guatemala and 
Venezuela, yet in general it gives a fairly thin milk. The variation in this respect cannot be 
due to a difference of species, differences of altitude, or range of temperature, but may possibly 
be connected with the condition of the soil and the annual rainfall. At the moment of 
issuing from the cuts the latex forms an almost pure white creamy mass, which, however, 
almost immediately begins to discolour, and in a very short time becomes brownish-black, 
changes due to the presence of an oxidising ferment in the latex. It is intensely bitter in 
taste, due, it is thought, to the presence of a glucoside, and contains a large percentage of 
albuminous matter, which may reach as much as 11 per cent. This latter fact is thought by 
Dr. Weber to account for the ease with which Castilloa latex can be coagulated, rather than 
the large size of the rubber globules to which it is generally attributed. 
The methods adopted by the native collectors for coagulating Castilloa latex vary con- 
siderably, and are usually of a very crude nature. The following are the most important : — 
1. The latex is washed with water, but just as often this is neglected, and is treated 
with a decoction of the crushed stem of the moon-plant, Calonyction speciosum, which is 
strongly acid in reaction. This is the process employed in British Honduras. 
2. The latex is treated with the juice expressed from Ipomcea bona nox , which is stated 
to be strongly alkaline, though this latter point is open to considerable doubt. 
3. The latex is collected in shallow holes dug in the ground, and is mixed with a boiling 
solution of soap in water. This method is extensively used in the Isthmus of Panama. 
4. The latex is treated with a solution of alum. 
