ess still the third
month. On an average twenty trees give about one litre of latex a day.
Three litres of latex are necessary in order to obtain one litre of
rubber. At the head-waters of the Arinos River 600 trees gave from 30 to
35 arobas (450 to 525 kils.) of fine rubber in the first month, and about
20 arobas (300 kils.) of _sarnambe_ (second quality with impurities). One
aroba is 15 kils.

The latex of the seringueira in the Arinos region was of a beautiful
white, quite liquid, and with a pungent, almost sickening, odour. When a
new tree was tapped, the lower towards the ground the incisions were made
the better. If after considerable tapping the tree did not yield much, it
was advisable to incise the tree higher up. In that region the trees
exuded latex more abundantly when they began to have new leaves in
October. Late in the dry season the latex flowed less freely. When the
weather was windy all the latex seemed to contract to the summit of the
trees and hardly flowed at all from the incisions. When it rained, on the
contrary, it flowed freely, but was spoilt by being mixed with water; so
that a good seringueiro must know well not only where and how, but also
when to tap the trees, in order to get good results.

[Illustration: Balls of Rubber outside a Seringueiro's Hut.]

[Illustration: Method of Pressing Rubber into Cakes.

The alum process of coagulation being used.]

Several ways were employed in order to coagulate the latex. The simplest
was the one used in Matto Grosso. The latex was poured into a rectangular
wooden mould, 0.61 m. long (2 ft.), 0.46 m. wide (11/2 ft.), and 0.15 m.
deep (about 6 in.). Upon the latex was placed a solution of alum and
warm water. Then coagulation took place. In order to compress the
coagulating latex into solid cakes, a primitive lever arrangement was
used--merely a heavy wooden bar, one end of which was inserted into the
cavity of a tree, above the wooden mould, while at the other end of the
bar heavy logs of wood were suspended. One night was sufficient for the
latex to coagulate thoroughly and be properly compressed into cakes,
weighing each about 221/2 kils. The cakes were lifted out by belts of liane
which had been previously laid into the moulds.

The discoverer of the method of coagulating rubber with alum was Henry S.
Strauss. He also found that by keeping the latex in hermetically sealed
vessels it could be preserved in a liquid state. The same result could be