t mn directed by experience 3*. to 4*. per lb. may be secured. The 
Hevea Brazdiensis yields the most satisfactory results on the 
Amazon and elsewhere, both in quantity and quality of milk. The 
climatic conditions favourable to its development are — a hot damp 
atmosphere, with the greatest possible amount of saturation, and a 
fairly dry warm soil. Excessive flooding is liable to cause "wet 
feet,” thus preventing the growth of the tree and oftentimes prov- 
ing fatal to it. 
The trees are tapped when upwards of 8 to 10 years old. The 
incisions are usually made in a series of V-shaped channels con- 
nected with each other by a horizontal channel about § inch deep 
by f inch wide. These must be most carefully cleansed and freed 
from any particle of sand, bark, vegetable fibre or grit of any kind. 
The collecting cups and cans also must be perfectly clean for 
cleanliness is really the first care, and upon its du ? observance 
depends largely the resulting product. The rubber manufacturer 
must have his raw material absolutely clean, and to secure this 
result the rubber is subjected to a process of rolling and heating 
and tearing between grooved friction rollers under a stream of 
water which washes away the foreign matter. Growers should 
always remember that the" value of the rubber to the manufacturer 
is the value of the weight of the washed product, not of the raw 
gum, as imported. In this connection we may mention that Para 
rubber will lose from 5 to 15 per cent, in weight, whilst some badly 
collected rubbers will lose as much as 50 to 70 per cent. The evil 
effect of this introduction of foreign matter is not limited to the 
corresponding loss of weight, for the necessary heating, tearing 
and rolling the rubber tends to weaken the gum,* to reduce its ten- 
sile strain and to break up its fibres, thus often causing a loss of 
the vitality of the rubber of from 5 to 25 per centage of foreign 
matter removed. 
Most unfortunately the otherwise good rubber of Rangoon and 
Assam contain 20 to 30 per cent, of barky matter, which render 
them unsuitable for the higher classes of work, as oftentimes some 
of these particles eventually find their way into the manufactured 
article. The waterproofing of a garment, the insulation of an 
ocean cable, or indeed any fine work may be rendered useless by 
the presence of these particles. In the case of a cycle inner tube, 
the grain of sand may become embedded in the thin structure of 
the tube, inflation causes this grain to "pop” out, subsequent infla- 
tations extend this point of fracture into a bubble which eventually 
bursts and spoils the tube. And yet all these difficulties could so 
easily be avoided by the exercise of due care in collection. It 
would not cost the collector much to make a practically clean rub- 
ber, whereas, on the other hand, the increased profit obtained 
thereby would be considerable. A few years ago the Congo rubbers 
were carelessly collected and realised barely is. 3, d . to is. 6d \ per 
lb. Now by careful collection good prices can be obtained, in 
some cases as much as 4s. to 4s. 3d. per lb. Cape Coast kinds have 
advanced from the same cause, whilst on the other hand many 
brands have decreased in price from careless and imperfect collec- 
