The Ely miner. [volume] (Ely, Minn.) 1895-1986, 1910-01-28

4 extensively as an insufat-
ing material, being one of the best
insulators Of electricity in the world.
Nearly all the wires that carry cleo
trical current are protected with rub
Der insulation. Rubber prevents the
electricity escaping through contact
of the wire with other conductors; 1t
prevents accidents, fires, and keeps
the electrical apparatus from burn
ing out and destroying itself. Besides
being used for insulating wires and
cables at the plants of the General
Electrical Company, rubber is used in
the manufacture of motors, switches,
generators, and nearly all electrical
machines.
The story of rubber is the story of
the conquest of the tropical 5ungles;
the fights against disease, poisonous
reptiles and insects, man-eating anil
mails, hunger and thirst and the dan
ger of being lost forever.
Civilization first heard of rubber in
Herrera's account of the second voy-
age of Columbus. in the year 1893,
where he speaks of elastic balls made
by the natives from the gum of a tree.
The first authentic account Of it's
practical use was recorded in 1745
by the leader of French government
expedition returning from South
America, who reported that the ma
tives secured from the juice of tree
certain gum which was very elastic,
impervious to water and used in max
ing bottles, shoes and squirt guns.
Thirty years later it was introduced
to commerce when an Englishman
brought from Assam, India, soft,
spongy substance which would erase
lead pencil marks and which after
wards became known as India rubber.
Many primitive uses were found
for this wonderful gum, but owing to
its susceptibility to changes Of tenn
perature, which rendered it sticky and
more or less fluid, rubber did not come
into it's own until early in the last
century. At that time it was discov-
cred, after a great deal Of expert
ment, that by mixing sulphur with
crude rubber and subjecting it to a
high degree of heat, these former de-
f1ciencies were eliminated and mate
rial was produced which was both
tough and elastic, and would retain
those properties under varying tenn
peratures. This process of curing was
called INFLAMMATION and is the basis
OF rubber making to-day.
So great has been the development
of rubber manufacture since the time
that its products now exceed a value
of $500,000,00O annually.
Contrary to the popular impression,
rubber gum is not derived from the
sap. 1t Is secured from a milky Juice
or latex which is found only in the
bark. This latex contains a substance
known as caoutchouc (the active prin-
ciple of RUBBER, together with GER
tain albuminoids, resins, etc., which
upon the evaporation of moisture
coagulate, forming a thick, spongy
substance. The percentage of caout-
chouc, in proportion to other ingredi-
ents contained in the later, deter
mines the quality of the rubber.
The regions from which rubber
gum is secured form an irregular belt
in the tropics and sub-tropics extend
ing around the earth, the quality pro-
cured varying greatly according to the
species of plant, the soil and the eli
mate. Great quantities are produced
in Africa, Mexico, Ceylon and the
Malay islands, but the most desirable
rubber of resiliency and wear resist
ance is secured from tree found in
the Amazon river district, South
America. This rubber is known as
Para, the name being derived from its
chief city Of export. 1t not only con-
tains as high as 95 per cent of caout-
chouc, but the methods used by tho
natives in preparing it for market are
20 much superior that it is selected