VULCANIZED RUBBER.
EARLY USE OF CAOUTCHOUC BY THE INDIANS--COLLECTION OF THE GUM--EARLY
EXPERIMENTS FAILURES--GOODYEAR’S PERSISTENT EXPERIMENTS--NATHANIEL
HAYWARD’S APPLICATION OF SULPHUR TO THE GUM--GOODYEAR’S PROCESS OF
VULCANIZATION--INTRODUCTION OF HIS PROCESS INTO EUROPE--TRIALS AND
IMPRISONMENT FOR DEBT--RUBBER SHOE INDUSTRY--GREAT EXTENT AND
VARIETY OF APPLICATIONS--STATISTICS.
Most all important inventions have grown into existence by slow stages
of development, and by successive contributions from many minds, not a
few having descended by gradual processes of evolution from preceding
centuries. Vulcanized rubber, however, is not of this class. It belongs
exclusively to the Nineteenth Century, and owes its existence to the
tireless energy of one man. The value of the crude gum had been
previously speculated upon, and for years attempts had been made to
utilize it, but not until Goodyear invented his process of vulcanizing
it did it have any real value. This process was an important, distinct
and unique step, entirely the work of Mr. Goodyear, and it has never
been superseded nor improved upon to any extent. Charles Goodyear was
born in New Haven, December 29, 1800, and his life, beginning two days
in advance of the Nineteenth Century, furnishes an extraordinary
illustration of the struggles and trials of the inventor against adverse
fortune, and is a pathetic example of self denial, indefatigable labor,
and unrequited toil. Of feeble health, small stature, poor, and
frequently in prison for debt, he made the development of this art the
paramount object of his life, and with a pious faith and unfaltering
courage for thirty years he devoted himself to this work. Money he cared
nothing for, except in so far as it was necessary to carry on his work,
and he died July 1, 1860, poor in this world’s goods, but rich in the
consciousness of the great benefit conferred by his invention upon the
human race.
[Illustration: FIG. 160.--COLLECTING THE GUM.]
India rubber, or caoutchouc, as it is more properly called, is a
concentrated gum derived from the evaporation of the milky juice of
certain trees found in South America, Mexico, Central America and the
East Indies. The South American variety is called _Jatropha elastica_,
and the East Indian variety the _Ficus elastica_. The South American
Indians called it _cahuchu_. The province of Para, south of the equator,
in Brazil, furnishes the largest part and best quality of gum. The tree
from which the gum exudes grows to the height of eighty, and sometimes
to one hundred feet. It runs up straight for forty or fifty feet without
a branch. Its top is spreading, and is ornamented with a thick and
glossy foliage. The gum is collected by chopping through the bark with a
hatchet and placing under each series of cuts a little clay cup formed
by the hands of the workman. About a gill of the sap accumulates in each
cup in the course of a day, and it is then transferred to receiving
vessels and taken to camp. The first use of the gum was made by the
South American Indians, who made shoes, bottles, playing balls and
various other articles from it. Their method for making a shoe was to
take a crude wooden last, which they covered with clay to prevent the
adhesion of the gum. It was then dipped in the sap, or the latter was
poured over it, which gave it a thin coating. It was then held over a
smoky fire, which gave it a dark color and dried the gum. When one
coating became sufficiently hard another was added, and smoked in turn,
and so successive coatings were applied until a sufficient thickness was
obtained. When the work was completed it was exposed for some days in
the sun, and while still soft the shoes were decorated as the fancy or
taste of the maker suggested. The clay forms were then broken out, and
the shoe stuffed with grass to keep it in shape for use or sale. In 1820
a pair of these clumsy shoes was brought to Boston and exhibited as a
curiosity. They were covered with gilding, and resembled the shoe of a
Chinaman. Subsequently considerable numbers of these shoes were brought
from South America, and being sold at a large price, they served to
stimulate Yankee ingenuity into devising methods of making them from the
raw material, which being brought as ballast in the ships from Brazil,
could be had cheaply. In France some attention had been given to the
material, and the rubber bottles of the Indians had been cut into narrow
threads which were woven into strips of cloth to form suspenders and
garters. In England an application of it in thin solution had been made
by a Mr. Macintosh, who spread it between two thicknesses of thin cloth
to form Macintosh water-proof coats. The first practical use of the gum
on a large scale was instituted by Mr. Chaffee in Roxbury, Mass., about
1830. He dissolved the gum in spirits of turpentine and invented
steam-heated rolls for spreading it upon cloth. Companies were formed to
exploit the products, and in the fall and winter of 1833 and 1834 many
thousands of dollars’ worth of goods were made by the Roxbury Company,
but the business proved a total failure, for in the summer the goods
melted, decomposed and became so offensive as to be worse than useless,
while the cold of winter rendered them stiff and liable to crack. With a
knowledge of these facts and conditions Charles Goodyear commenced his
experiments, believing that there was a great future for this material
if it could only be prevented from melting in summer and stiffening in
winter. He tried mixing it with many materials, first using magnesia,
which, however, proved ineffective. On June 17, 1837, he took out patent
No. 240, in which he proposed to destroy the adhesive properties of
caoutchouc by superficial application of an acid solution of the metals,
nitric acid with copper or bismuth being specially recommended. He also
claimed the incorporation of lime with the gum to bleach it. Under this
process Mr. Goodyear made various articles in the form of fabrics, toys
and ornamental articles, using the fabric to make clothing for himself,
which he wore to demonstrate its value and wearing qualities. A striking
word picture of Mr. Goodyear at this time is given by the reply of a
gentleman who, being asked by a man looking for Mr. Goodyear as to how
he might recognize him, replied, “If you meet a man who has on an India
rubber cap, stock, coat, vest, and shoes, and an India rubber money
purse in his pocket, without a cent of money in it, that is he.”
Many useful and artistic articles were made under this first patented
process, including maps, surgical bandages, etc., and were brought by
Mr. Goodyear to the notice of President Jackson, Henry Clay and John C.
Calhoun, from whom he received very encouraging letters. His efforts,
however, to introduce his process commercially were not attended with
success. Capitalists and manufacturers had been rendered so conservative
by the large loss of money in the Roxbury Company, that they were
disinclined to have anything further to do with it. Practically alone he
was obliged to continue his work. By the kindness of Mr. Chaffee and Mr.
Haskins he was allowed the use of the valuable machinery standing idle
in their factory at Roxbury, and he made shoes, piano covers, table
cloths and carriage covers of superior quality, and from the sale of
these, and of licenses to manufacture, he for the first time was able to
support his family in comfort. Mr. Goodyear had not yet discovered,
however, the process of vulcanization, upon which the rubber industry is
founded. In 1838 Mr. Nathaniel Hayward, of Woburn, Mass., who had been
employed in the bankrupt rubber company, discovered that the stickiness
of the rubber could be prevented by spreading a small quantity of
sulphur on it. The same result had also been noticed by a German
chemist. On Feb. 24, 1839, Mr. Hayward procured the patent, No. 1,090,
on his process, and assigned it to Mr. Goodyear. The patent covered a
process of dissolving sulphur in oil of turpentine and mixing it with
the gum, and also included the incorporation of the dry flowers of
sulphur with the gum, the product afterwards being treated by Mr.
Goodyear’s metallic salt process. This was the starting point of
vulcanization, for vulcanization consists simply in admixing sulphur
with the rubber, and then subjecting it for six to eight hours to a
temperature of about 300°. Its effect is to so change the nature of the
gum to prevent it from melting or becoming sticky under the influence of
heat, or of hardening and becoming stiff under the influence of cold,
the vulcanized gum remaining elastic, impervious, and unchangeable under
all ordinary conditions. This great discovery of the influence of heat
on the sulphur treated gum was quite accidental and wholly unexpected.
Heat above all things was the agency which in all previous observations
was most to be feared, for it was this more than anything else that
melted down, decomposed and destroyed all of his manufactured articles.
While sitting near a hot stove engaged in an animated discussion
concerning his experiments, a piece of the gum treated with sulphur,
which he held in his hand, was, by a rapid gesture, thrown upon the
stove. To his astonishment, he found that this relatively high heat did
not melt it, as heretofore, and while it charred slightly, it was not
made at all sticky. He nailed the piece of gum outside the kitchen door
in the intense cold, and upon examining it the next morning found it as
perfectly flexible as when he put it out. Goodyear had discovered the
process which afterwards came to be known as “vulcanization.” The
discovery was made in 1839, but was not accepted by those to whom it was
submitted as possessing any importance. Prof. Silliman, of Yale College,
however, in the fall of 1839 testified to the results claimed for it by
Mr. Goodyear--that it did not melt with heat, nor stiffen with the cold.
On June 15, 1844, Mr. Goodyear took out his celebrated patent, No.
3,633, covering this process, in which he not only used sulphur, but
added a proportion of white lead. The proportions named were 25 parts of
rubber, 5 parts of sulphur, and 7 parts of white lead, the ingredients
either to be ground in spirits of turpentine, or to be incorporated dry
between rolls. The odor imparted by the sulphur was to be destroyed by
washing with potash or vinegar. This patent was reissued in two
divisions Dec. 25, 1849, and again on Nov. 20, 1860, and was extended
for seven years from June 15, 1858, which was the end of the first term.
Under this patent two kinds of rubber were made and sold--“soft rubber,”
containing only a small proportion of sulphur, while the other, known as
the “vulcanite,” “ebonite,” or “hard rubber,” had from 25 to 35 per
cent. of sulphur and was subjected to a longer heat.
The history of this patent is a remarkable one. Immensely valuable as it
was, Goodyear reaped but a small share of the profit, for in the midst
of his poverty and necessities he was obliged to sell licenses and
establish royalties at a figure far below the real value of the rights
conveyed. Some idea of the great value of the business which Mr.
Goodyear had developed may be had from the fact that the companies who
held rights under the patent for the manufacture of shoes paid at one
time to Daniel Webster the enormous fee of $25,000 for defending their
patent interests.
With the idea of extending his invention Mr. Goodyear visited England in
1851, where he found that Thomas Hancock, of the house of Macintosh &
Co., had forestalled him, although not the inventor. A peculiar
provision of the English patent law, which gives the patent to the first
introducer, permitted this. Nothing daunted, however, he organized a
magnificent exhibit for the Great International Exhibition held in
Crystal Palace at Hyde Park, London, in 1851. This exhibit cost him
$30,000, and he called it the Goodyear Vulcanite Court. It comprehended
an elegantly constructed suite of open rooms made of hard rubber
ornamented with handsome carvings, and furnished with rubber furniture,
musical instruments, and globes made of rubber, and it was also carpeted
with the same material. For his exhibit he received the “Grand Council
Medal,” which was one of the highest testimonials of the exposition.
This exhibit was afterwards moved from London to Sydenham, where it was
exposed and used as an agency for some years for the sale of rubber
goods.
[Illustration: FIG. 161.--MACHINE FOR GRINDING AND WASHING CRUDE
RUBBER.]
Mr. Goodyear had obtained a French patent for his invention, and at the
Exposition Universelle in Paris, in 1855, he fitted up at an expense of
$50,000 two elegant courts with India rubber furniture, caskets and rich
jewelry, and for this exhibit he had conferred upon him by the Emperor
Napoleon the “Grand Medal of Honor” and the “Cross of the Legion of
Honor.” It was a singular instance of the irony of fate that the
decoration of the “Cross of the Legion of Honor” should have been
conveyed to him while imprisoned for debt in “Clichy,” the debtors’
prison in Paris. The lofty courage of the man was well illustrated at
this time in his reply to his wife’s solicitous inquiries as to how he
had spent the night while in prison. He said, “I have been through
nearly every form of trial that human flesh is heir to, and I find that
_there is nothing in life to fear but sin_.” The declining years of his
life were full of sorrow, pain and affliction, and at his death in 1860
his estate was $200,000 in debt. He lived long enough, however, to see
his material applied to nearly five hundred uses, giving employment in
England, France and Germany to 60,000 persons, and producing in this
country alone goods worth $8,000,000 a year.
[Illustration: FIG. 162.--MAKING RUBBER CLOTH.]
The greatest of all applications of rubber are to be found in the
manufacture of boots and shoes. The number of attacks of cold,
rheumatism, and death-dealing diseases from wet feet, that have been
averted by the use of rubber shoes, can never be estimated, but perhaps
it is safe to say that the rubber shoe has done more to conserve the
health of the human family than any other single article of apparel.
In the manufacture of shoes the finest quality of rubber is received in
wooden boxes 4 × 2 × 1½ feet, containing about 350 pounds in lumps of 1
to 75 pounds. These lumps are cut to suitable size, and are then ground
and washed in the machine shown in Fig. 161, water and steam being
sprayed on the rubber during the operation. It is then worked into
sheets or mats between rolls. From the grinding room the sheets are
taken to the mixing room, where lampblack, sulphur and other ingredients
are added, and worked into it by being passed many times between heated
rolls, the sheets being finally reduced to a thickness of less than 1/32
of an inch. The rubber sheets are then applied to a cloth backing by
cloth calendering rolls, shown in Fig. 162, which are steam heated and
by great pressure serve to incorporate the sheets of rubber and cloth
into intimate and inseparable union. Out of this rubber fabric, which is
made of different thicknesses for the upper, sole and heel, the patterns
for the shoe are cut, and the parts are deftly fitted around the forms
by girls, and secured by rubber cement, as shown in Fig. 163. The shoes
are then covered with a coat of rubber varnish, and are put into cars
and run into the vulcanizing ovens, where they remain from six to seven
hours at a temperature of about 275°. The goods are then taken out, and
after being inspected are boxed for the market. The vulcanizing is a
very important part of the manufacture of a rubber shoe, for it is
absolutely necessary in order to give them stability and wearing
qualities. A shoe that had not been vulcanized would mash down, spread,
become sticky and go to pieces after a few hours’ wear.
The rubber shoe industry of the United States is carried on by about
fifteen large companies, representing an investment of many millions of
dollars, most of which companies are located in Massachusetts, Rhode
Island and Connecticut.
Some idea of the immensity of this industry may be obtained from the
import statistics. In 1899 the United States alone imported crude rubber
to the extent of 51,063,066 pounds, as much as 1,000,000 pounds a month
coming from the single port of Para. The export of manufactured rubber
goods for the same year amounted to $1,765,385. The statistics for Great
Britain for 1896 showed the imports of rubber to that country to be
one-third more than the imports of the United States. Germany also is a
large consumer. The great Harburg-Vienna factories cover sixty-seven
acres, are capitalized at 9,000,000 marks, and employ 3,500 hands. Much
fine technical apparatus, toys, and balls are made here, the daily
output of balls reaching 8,000. These, with the Noah’s arks of India
rubber animals, are the delight of the little ones all over the world.
Although so much in evidence about us, India rubber is not by any means
a cheap material. Costing only five cents a pound when Goodyear
commenced his experiments, it is now worth a dollar a pound, and is
therefore much more expensive than any of the ordinary metals, woods, or
building materials. Many substitutes in the form of compositions of
various ingredients have been devised and patented, but no real
substitute for nature’s product has yet been found. For many years old
and worn out rubber goods were thrown away as worthless. Now all such
rubber is reclaimed, and used in many grades of goods which do not
require a pure gum. Insatiable as the demands of the trade may appear,
there is no need to fear a rubber famine, for the forests of trees in
South America and the East Indies are practically inexhaustible, and in
the rich alluvial soil of their habitat nature’s processes of growth
rapidly restore the decimation.
[Illustration: FIG. 163.--MAKING RUBBER SHOES.]
Since the time of Goodyear, the amplification of this art and the
multiplication of uses for rubber, and its increased commercial
importance, have gone on at such a rate of increase that to-day we may
be said to be living in the rubber age. Its uses and applications are
legion, and they extend literally from the cradle to the grave. When the
baby comes into the world its introduction to India rubber begins at
once with the nursing bottle and the gum cloth, and when the aged
invalid takes leave of the world his last moments are soothed with the
water bag and the rubber bed, and between these extremes we find it in
evidence everywhere about us. In wearing apparel it extends from the
crown of the head to the sole of the foot--rubber cap, coat, gloves, and
shoes. The man has it in his suspenders and his pipe stem, the woman in
her garters and dress shields, and the baby in its teething ring and
rattle. The soldier stands on picket duty in the rain, and the rubber
blanket protects him from rheumatism. If wounded, the surgeon dresses
his mangled limb with rubber bandages, and when he gets well he has a
rubber cushion on the end of his crutch, or on the foot of his
artificial leg. If wounded in the mouth perhaps the government gives him
a set of artificial teeth on a rubber plate. The rubber mat greets you
at the front door, a little pad cushions the door stops and the backs of
chairs, and a ring seals the mouth of the fruit jar. The whole array of
toilet articles, including combs, brushes, mirrors, shoe horns, etc.,
are made from it. In the parlor it is found in picture frames and the
piano cover; in the bath room the wash rag, water bag, rubber cup, and
hose pipe of the shower bath are all made of it; in the play room are
found rubber balls and toys of all kinds; in the kitchen the clothes
wringer and the table cloth; in the dining room the handles of knives,
and the tea tray, and what is more useful and more ubiquitous in the
office than the rubber band, the rubber ruler, the pencil eraser, or the
fountain pen? But these are only a few of the personal and indoor uses
and applications. Rubber belting for machinery, fire engine and garden
hose, steam engine packing, car springs, covers for carriages and the
big guns of the navy, life preservers, billiard table cushions, and
chemical and surgical apparatus in endless variety. The electrical world
is almost entirely dependent upon it for the insulation of our ocean
cables and electric light wires, for battery cups, and the insulating
mountings of all electrical apparatus. The pneumatic bicycle tire could
not exist without rubber, and the modern application of it to this use
alone amounts to nearly four million pounds annually. Every automobile
carriage takes twenty-five pounds of rubber for each tire, or 100 pounds
altogether. This great and growing industry, together with the now
common use of rubber tires on horse-drawn vehicles, raises the sum total
of rubber employed in the arts to an enormous figure.
That the sap of an uncultivated tree in a swampy, tropical, and malarial
forest, thousands of miles from civilization, should cut so great a
figure in the necessities of modern life, seems strange and
unaccountable on any basis of probabilities. It is only another
illustration of the possibilities of the patient and persistent work of
the inventor. Charles Goodyear took this nearly worthless material, and
made of it, as Parton said in 1865--“not a new material merely, but a
new class of materials, applicable to a thousand divers uses. It was
still India rubber, but its surface would not adhere, nor would it
harden at any degree of cold, nor soften at any degree of heat. It was a
cloth impervious to water; it was a paper that would not tear; it was a
parchment that would not crease; it was leather which neither rain nor
sun would injure; it was ebony that could be run into a mould; it was
ivory that could be worked like wax; it was wood that never cracked,
shrunk nor decayed. It was metal, ‘elastic metal,’ as Daniel Webster
termed it, that could be wound round the finger, or tied into a knot,
and which preserved its elasticity like steel. Trifling variations in
the ingredients, in the proportion and in the heating, made it either
pliable as kid, tougher than ox hide, as elastic as whalebone, or as
rigid as flint.”