Henry Chase Hill

Rubber is the coagulated sap of more than 300 varieties of tropical trees and vines—the Landolphia of Africa, the Ficus of the Malay Peninsula, the Guayule shrub of Mexico and the Castilloa of South America, Central America and Southern Mexico are all important rubber producers, but far more important than all of the others together is the Hevea, a native of Brazil.

Hevea trees are scattered through the dense forests of practically every part of the Amazon Basin, a territory more than two-thirds as large as the United States.

How was Rubber First Used?

Down in Brazil, several hundred miles up the Amazon River, there stood a great forest of trees and in this forest—the same as in forests of today—were birds and animals and bugs and beetles, etc. All trees are protected by nature; some are protected from bugs eating their leaves, by other bugs eating up these bugs; other trees are protected by having a thorny or bristly bark.

Handball playing Indians

Indians Playing With a Rubber Ball When Columbus Came in Sight

Courtesy of the United States Rubber Co.

In these forests in which the rubber tree grows there was a wood-boring beetle, and this beetle would attack these rubber trees, boring into them; but the tree, in order to protect itself, had a poisonous juice, and as soon as the beetle bored into the tree, this juice killed him. Then the juice would fill up the hole the beetle had made, and the tree would go on growing as before.

In those days the natives around these forests (who were half Indian and half Negro) happened to find some of this juice sticking on the tree. They cut it off, rolled it together and made a ball, with which they would play games. The first mention of it was made by Herrera in his account of the second voyage of Columbus, wherein he speaks of a ball used by Indians, made from the gum of a tree which was lighter and bounced better than the far-famed balls of Castile.

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Snapshots of rubber production

In the Jungle
Llama, Domestic Animal of the Andes, Used to Carry Rubber over Mountains
Railroad Around the Rapids of the Madeira Terminal
Crude Rubber “Biscuits” on the Banks of the Amazon

Courtesy of the United States Rubber Co.

The way they gather this rubber is very interesting. When it comes from the tree it is nothing but a milky juice. The natives of South America soon discovered that the white man was willing to pay them beads and other trinkets for chunks of this rubber, so they became active in gathering it.

River in Brazil

On the Banks of the Rio Guapore—Brazil

Courtesy of the B.F. Goodrich Co.

What is a Rubber Camp Like?

In this locality the rubber harvest commences as soon as the Amazon falls which is usually about the first of August. When this date approaches bands of natives set out from their primitive homes and go, in many instances, hundreds of miles into the forest lowlands. There, within easy reach of the rubber trees, they set up their camp and the actual work of harvesting the rubber crop begins. It usually covers a period of about six months, extending from August to January or February.

The camps are usually great distances from the nearest town and procuring supplies is not only difficult but very expensive as well. The natives build their huts out of small poles covered with palm thatch and live in little colonies while the rubber harvest is going on. The Brazilian name for a rubber gatherer is “seringuero.”

Hut in jungle

Rubber Gatherer’s Hut Near the Amazon

Courtesy of the B.F. Goodrich Co.

A roof and floor with the flimsiest of walls, set up on piling for coolness, defense against animals and insects, and to keep the building dry during flood season, forms the home of the rubber gatherer. The more pretentious and better furnished home of the superintendent of the “estate,” together with the storehouses, etc., are called the “seringal.”

The buildings are usually grouped together at a favorable spot on the banks of the Amazon or one of its tributaries.

Furniture is of the most primitive type. The laborers and their families sleep in hammocks or on matting on the floor. Food is largely made up of canned goods and the ever-present farina, a sort of tapioca flour.

The climate of the South American rubber country is usually fatal to white men, and even among the Indians the fevers, the poisonous insects and reptiles, and the other perils of a tropical forest cause a high death rate. The production of South American rubber is limited by a shortage of men rather than a shortage of trees.

In December the rainy season begins. The waters of the Amazon begin to rise and the work ceases. The superintendent and many of the workers go down the river to Para and Manaos or to villages on higher ground. However, a number of the laborers usually remain in the huts, loafing and fighting the animals and insects that seek refuge from the rising waters. They have but little to eat, and during the entire season practically no communication with the outside world.

Hut in the jungle

A Home of the Rubber Gatherers

Courtesy of the United States Rubber Co.

At the end of the rainy season, early in May, the laborers return to their task. The quick-growing vegetation has filled the estradas and this must be cleared away and perhaps new estradas opened. An estrada is simply a path leading from one Hevea tree to another and circling back to camp. Each estrada includes about one hundred of the scattered Heveas.

After having established themselves in camp the natives take up their monotonous round, which is followed day after day as long as the rubber trees continue to yield their valuable sap. When the seringuero starts out he equips himself with a tomahawk-like axe having a handle about thirty inches long. This is called a “macheadino.”

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Cutting the rubber tree

Tapping Hevea Rubber Tree—Brazil

Courtesy of the United States Rubber Co.

How is Rubber Gathered by the Natives?

The trees are tapped very much like maple syrup trees. Only the juice is found between the outer bark and the wood. So these men make a cut in the tree through the bark, almost to the wood. A little cup is then fastened to the tree with a piece of soft clay to press the cup against it, and the juice runs into this cup. Sometimes they have from ten to thirty cups on one tree and the average yield of a tree is ten pounds of rubber a year.

Some two hours after the tapping is done the flow entirely ceases and the tree must be tapped anew to secure a fresh flow.

The film of rubber that forms on the inside of the cup and the bits of rubber remaining on the tree are collected and sold as coarse Para.

Riverview

On the Banks of the Amazon

Courtesy of the B.F. Goodrich Co.

Collecting raw rubber milk	Raw rubber milk dripping from tree
Gathering the Rubber Milk—Brazil	How the Rubber Milk Drips from the Gash in the Tree—Brazil
Courtesy of the United States Rubber Co.

The rubber gatherer carries in addition to a macheadino and many small tin cups, a larger vessel for gathering the liquid and carrying it to camp. One man will tap as many as 100 trees in a single morning and then cover the same ground again in the afternoon or on the following morning, gathering the sap that drips slowly from the cuts made in the trees. On these journeys the harvester frequently travels long distances over paths so buried by the undergrowth of the jungle that they are almost invisible to the untrained eye. On such expeditions rubber gatherers usually go armed with rifles to protect themselves against wild animals, reptiles and savage Indians.

Rubber tapping on Borneo

A Plantation in Borneo

Courtesy of the B.F. Goodrich Co.

How is Rubber Smoked?

After the juice has been gathered in this way, the native builds a fire; over it he places a cover shaped like a large bottle with the bottom knocked out of it. This fire is built of oily nuts found in the forest, and the thick smoke arises through what would be the neck of the bottle.

Smoking rubber in the jungle

Smoking Rubber on the Lower Amazon

Courtesy of the United States Rubber Co.

With a stick shaped something like the wooden shovels used at the seashore, he dipped into the milky juice in the bowl, then turned this stick or paddle around very rapidly in the smoke until the juice baked on the paddle. He then added more juice and went through the same operation again and again until there were between five and six pounds of rubber baked on this paddle. He then cuts this off with a wet knife which made it cut more rapidly. That formed what is called a rubber “biscuit,” and he then started over again for his next five or six pounds. Later, as the demand for these “biscuits” increased, instead of the native using the paddle, he erected two short fence-like affairs about six feet apart, but parallel with each other, and in between was the smoky fire. Then he obtained a long pole, stretched it across these two rails and poured a small quantity of this juice on this pole, over where the smoke came in contact with it, and rolled the pole around until this juice was baked, adding more, until, instead of a small five- or six-pound “biscuit,” he would get an immense ball. In order to get this off his pole, he would jog one end of the pole on the ground until the “biscuit” would slide off. This is the way crude rubber first came into our market and the way it comes today.

Smoking rubber in the jungle

Smoking Rubber—Upper Amazon

Courtesy of the United States Rubber Co.

How was Vulcanizing Discovered?

Up to this time, these “biscuits,” when exposed to heat, would become very soft and sticky, and when exposed to the cold, would become hard like a stone.

Jogging off the ball of smoked rubber

Removing Biscuit from Pole after Smoking

Courtesy of the United States Rubber Co.

There was an American by the name of Charles Goodyear who had heard how the natives of the rubber-growing countries used this milky juice in many ways for their own benefit. One use they put it to was the waterproofing of their cloaks. How could this be done so that our clothing would be made water-tight and yet not be sticky in summer or stiff in winter? Goodyear devoted a great deal of his time to solving this problem, and, like many other great inventors, he passed through many trials. His many failures caused his friends to forsake him and he was put in prison for not paying his debts. He persisted in his quest, however, and it was accident at last that opened the way to discovery of the processes of vulcanization for which Goodyear was seeking.

Indian Waterproofing Cloth by “Painting” it with Rubber “Milk”—Brazil

Courtesy of the United States Rubber Co.

At Woburn, Mass., one day, in the spring of 1839, he was standing with his brother and several other persons near a very hot stove. He held in his hand a mass of his compound of sulphur and gum, upon which he was expatiating in his usual vehement manner, the company exhibiting the indifference to which he was accustomed. In the crisis of his argument he made a violent gesture, bringing the mass in contact with the stove, which was hot enough to melt India-rubber instantly; upon looking at it a moment afterwards, he perceived that his compound had not melted in the least degree! It had charred as leather chars, but no part of the surface had dissolved. There was not a sticky place upon it. To say that he was astonished at this would but faintly express his ecstasy of amazement. The result was absolutely new to all experience—India-rubber not melting in contact with red-hot iron! He felt as Columbus felt when he saw the land bird alighting upon his ship and the driftwood floating by. In a few years more his labors were crowned with success.

This great invention made it possible for us to have rubber boots and rubber shoes and many other things made of rubber.

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Up to this time, all the rubber was called Para rubber, named from the town of Para in Brazil, from which all rubber was shipped. The full-grown tree is quite large, ranging sixty feet and over in height and about eight feet around the trunk. It has a flower of pale green color and its fruit is a capsule containing three small brown seeds, with patches of black. These seeds lose their life very quickly, so a great deal of care is necessary to pack them if they are wanted to plant in another place. The safest way is to lay them loosely in a box of dry soil or charcoal.

The rubber tree grows best in rich, damp soil and in countries where the temperature is eighty-nine to ninety-four degrees at noon-time and not less than seventy-four degrees at night, and where there is a rainy season for about six months in the year, and the soil and atmosphere is damp the year round.

The name of this species of tree is Hevea, but many years ago it was called Siphonia on account of the Omaqua Indians using squirts made of a piece of pipe stuck into a hollow ball of rubber.

How did Rubber Growing Spread to Other Places?

Back in the seventies an English botanist, Wickham by name, smuggled many Hevea seeds out of Brazil. The tree was found to grow well in the Eastern tropics and today the rubber plantations of Ceylon, Borneo, the Malay Peninsula and neighboring regions are producing more than half of the world’s supply of crude rubber. Here the natives work under pleasant climatic conditions and the trees under cultivation grow better and yield better than in the forest.

On these plantations, rubber trees are cultivated just the same as other crops. All weeds are removed and great care is used with the young trees. Low-growing plants which absorb nitrogen from the air which enriches the soil, such as the passion flower and other sensitive plants, were planted around these small rubber trees, for it was found that when the weeds were removed to give the trees a chance to grow, the ground became hard and dry.

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The method of tapping is different, too. Instead of ten to thirty taps, a series of cuts the shape of a V is made on four sides of the tree, from the bottom up to as high as a man can reach, and a cup placed at the point of the V. Another way is to make one long cut down the tree and then cut out slanting channels about one foot apart into this, and put a cup at the bottom of the long cut; another is making a spiral around the tree with the cup at the bottom.

How is Rubber Cured on Modern Plantations?

With these big plantations some other way to cure the rubber had to be devised from the smoking process used in curing the native rubber which comes from South America. The milky juice is emptied from the cups into a tank and lime juice is added and it is then allowed to stand. The juice, as it comes from the tree, contains considerable water: the lime juice is added to separate the rubber from the water.

Sometimes separators are used much like our cream separators; in fact, the whole process and the appearance of the interior of these rubber “dairies” very much resembles our own dairies where real milk is made into butter, curds or cheese.

Para, at the mouth of the Amazon, and Manaos, a thousand miles up, are both modern cities of more than one hundred thousand population. They have schools, churches, parks, gardens and museums, and, except for the Indians, certain peculiarities in architecture and the ever-present odor of rubber, they differ but little from our northern cities of equal size. Here the rubber markets are located and here the rubber is carefully examined, graded, boxed and shipped to New York or Liverpool.

Plantation rubber usually comes in the form of sheets of various shapes and sizes. The rubber shown here is in oblong sheets. Sometimes it is in the form of “pancakes” or in “blocks.” Often, after being coagulated, it is smoked, and “smoked plantation sheet” is, next to Para, the best rubber obtainable.

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How is Crude Rubber Received Here?

Crude rubber is received in many forms under various names. There are more than three hundred standard kinds, depending on source and method of handling; e. g., “Sernamby” is simply bundles of Para tree scrap and scrap from the cups where milk has cured in the open air. “Guayule” is a resinous rubber secured from a two-foot shrub that grows on the arid plains of Texas and Northern Mexico.

Our picture shows a bin of crude up-river Para the finest rubber known. Every “biscuit” or “ham” has been cut in two to find out whether the native has loaded it in any way.

How is Rubber Prepared for Use?

Now that we have rubber so that it can be used, we find there are a great many operations necessary between gathering the crude rubber and finally the finished rubber coat or shoe. These various operations are called washing, drying, compounding, calendering, cutting, making, varnishing, vulcanizing and packing and each one of these main operations requires several smaller operations.

The grinding and calendering department is the one in which the crude rubber is washed, dried, compounded and run into sheets ready to be cut into the various pieces which constitute a boot or shoe.

The cultivated rubber comes practically clean, but the crude rubber “biscuits” contain more or less dirt and foreign vegetable matter which have to be removed. The rubber is softened in hot water for a number of hours and then passed through the corrugated rolls of a wash mill in which a stream of water plays on the rubber as it is thoroughly masticated and formed into thin sheets. These sheets are taken to the drying loft. Here they are hung up so that the warm air can readily circulate through them and are allowed to remain from six to eight weeks, until every trace of moisture has been removed. The vacuum dryer is used where rubber is wanted dry in a short space of time. This is a large oven containing shelves. The wet sheets of rubber are cut in square pieces, placed on perforated tin pans and loaded into the dryer, which will hold about eight hundred pounds of rubber. The doors are closed, fastened, and by the vacuum process the water is extracted, leaving the rubber perfectly dry in about three hours’ time.

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After the rubber is dry, and has been tested by the chemist, it goes to the grinding mills where it is refined on warm rolls and made ready for the compounding or mixing. It is impossible to make out of rubber alone, shoes or other products that will withstand extreme changes in temperature; certain amounts of sulphur, litharge and other ingredients are necessary in combination with the pure rubber to give a satisfactory material. The gum from the grinding mills is taken to the mixing mills, where, between the large rolls, the various materials are compounded into a homogeneous mass. The compounded rubber goes from the mixing mills to refining mills, to be prepared for the calenders.

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Automobile, motorcycle and bicycle tires, belting, footwear and many other rubber articles must have a base or backbone of cotton fabric, and in order that the fabric may unite firmly with the rubber it must be “frictioned” or forced full of rubber. This is done by drawing it between enormous iron rollers, rubber being applied on its surface as it passes through. The pressure is so great that every opening between the fibers of cotton, every space between threads is forced full of rubber.

The fabric is then ready to go with the milled rubber to the various departments of the factory to be incorporated into rubber goods. The calender is also used to press rubber into sheets of uniform thickness.

How are Rubber Shoes Made?

In making footwear, the linings and such parts as can be piled up layer on layer are cut by dies, usually on the large beam-cutting machines, commonly seen in leather shoe factories. The uppers are cut by hand from the engraved sheets, while metal patterns are used on the plain stock. The soles are cut by specially designed machines. The sheets of rubber from which the uppers and soles are cut are at this stage of the work plastic and very sticky. It is necessary on this account to cut the various pieces one by one and keep them separate, by placing them between the leaves of a large cloth book. In an ordinary rubber shoe there are from twelve to fifteen pieces, while in a common boot there are over twenty-five pieces.

The various pieces are next delivered to the making department, where they are fitted together on the “lasts” or “trees” in such a way that all the joints and seams are covered and the lines of the shoe kept exactly. Considerable skill is required to do this, as all the joints and seams must be rolled down smooth and firm to ensure a solid boot or shoe. The goods are all inspected before they are loaded on the iron cars to go to the varnishing department, where they receive the gloss which makes them look like patent leather.

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From the varnishing department the shoes are taken to the vulcanizers, which are large ovens heated by innumerable steam pipes. The shoes remain in these vulcanizers from six to seven hours, subjected to extreme heat. This heating or vulcanizing process fixes the elasticity of the rubber, increases its strength enormously and unites the parts in such a way as to make the shoe practically one piece.

The shoes next go to the packing department, where they are taken off the “lasts,” inspected, marked, tied together in pairs, sorted and packed. They are then sent to the shipping department to be shipped immediately or stored in one of the spacious storehouses.

How are Automobile Tires Made?

In making tires, the strips of fabric are built together about a steel core to form the body or carcass of the tire. The beads are also added. The side strips, the breaker strip and finally the tread are applied. All of these pieces are sticky, and as they are laid together and rolled down by small hand rollers they adhere to each other, and when the tire is completed it looks very much like the tires you see on automobiles, but it is not yet vulcanized. The rubber is much like tough, heavy dough—there is not much stretch to it and in a cold place it would become hard and brittle.

The tire on its steel core is taken to the mold room and placed in a steel box or mold, shaped to exactly enclose it. It is then placed with many others on a steel frame and lowered into a sort of a well or oven, where it remains for a time under pressure in the heat of live steam, after which it is removed, a finished tire.

Vulcanization is simply the heating of the rubber mixed with sulphur—this causes a chemical change in the substance; it becomes tougher, more elastic and less affected by heat and cold.

This process, discovered in 1839, made rubber the useful substance it is today. The discoverer, Charles Goodyear, to whom we referred before, was never connected in any way except by name with any of the manufacturers of the present day, but his discovery was the real beginning of a great industry.

How did the Expression “Before you can say Jack Robinson” Originate?

Jack Robinson was a man in olden days who became well known because of the shortness of his visits when he came to call on his friends, according to Grose, who has looked up the subject very carefully. When the servants at a home where Jack Robinson called went to announce his coming to the host and his assembled guests, it was said that they hardly had time to repeat his name out loud before he would take his departure again. Another man, Halliwell, who has also investigated the development of the expression, thinks that it was derived from the description of a character in an old play, “Jack, Robes on.”

It is also interesting to learn that the sandwiches which we all enjoy so much at picnics are so called because of the fact that an English nobleman, the Earl of Sandwich, always used to eat his meat between two pieces of bread.

What is an Aerial Railway Like?

Wonderful ingenuity has been shown in contriving a means to enable people to ascend the Wetterhorn Mountain in Switzerland. The sides of the mountain are so irregular and rough in their formation that it was found impossible to build even the incline type of railway, such as is usually resorted to where the ascent to a mountain is particularly steep. So the engineers who studied the problem finally contrived two huge sets of cables, securely fastened at the top, and fixed to a landing place a short distance from the base of the mountain. Cars, holding twenty passengers each, are carried up and down these cables, one car balancing the other, by means of a cable attached to each, which passes around a drum at the top.

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There is probably no railway in all Europe upon which travel affords more wonderful scenery than this trip, suspended in the air, up the side of the Wetterhorn Mountain, the three peaks of which are all considerably more than two and a quarter miles high.

Why are They Called “Newspapers”?

Although something like an official newspaper or government gazette existed in ancient Rome, and Venice in the middle of the sixteenth century also had official news sheets, the first regular newspaper was published at Frankfort in 1615. Seven years later the first regular newspaper appeared in England.

It was customary to print the points of the compass at the top of the early single-sheet papers, to indicate that occurrences from all four parts of the world were recorded. Before very long, the publisher of one of the most progressive papers rearranged the letters symbolic of the points of the compass, into a straight line, and printed the word NEWS, and in a very short time practically every newspaper publisher decided to adopt the idea.

It is interesting to find that American colonies were not far behind England in establishing newspapers, and equally interesting to know that the most remarkable development of the newspaper has been in the United States, where, in proportion to population, its growth and circulation has been much greater than in any other country. Practically a half of all the newspapers published in the world are published in the United States and Canada.

Every trade, organization, profession and science now has its representative journal or journals, besides the actual newspapers and magazines of literary character, and Solomon’s remark might be paraphrased to read: “To the making of newspapers there is no end.”

The great and rapid presses of recent years, the methods of mechanical typesetting and the cheapness and excellence of photographic illustrations, have all been necessary elements of the great sheets and enormous circulations of the present day, and the twentieth century newspaper is one of the greatest achievements in the whole field of human enterprise.

How Did the Cooking of Food Originate?

As soon as man found that he could produce fire by friction, as the result of rapidly rubbing two sticks together, he began to have accidents with his fires, just as we do today. And it was probably because of one of these accidents, in which some food was cooked quite unintentionally, that primitive man made the great discovery that most of the meats and fruits and roots that he had been accustomed to eating raw, were far better if they were put in or near the fire for a while first.

How Far Away is the Sky-Line?

Unless you happen to be of the same height as the person standing next to you, the sky-line is a different distance away from each of you, for it is really just a question of the distance the eye can see from different heights above the sea-level. A person five feet tall, standing on the beach at the seaside, is able to see about two and three-quarter miles away, while one a foot taller can see about a quarter of a mile further.

A person on the roof of a house a hundred feet high is able to see more than thirteen miles away, on a clear day, and a forty-two mile view may be enjoyed from the top of a mountain a thousand feet high. The aviator who goes up to a level a mile above the sea is able to see everything within a radius of ninety-six miles and the further up he goes the larger the earth’s circle becomes to him.