Part 43

Para rubber is sold in three grades. Fine Para, which is the more carefully coagulated or smoked rubber; Medium Para, which is rubber gathered and smoked in the same way as Fine, but which has had insufficient smoking, and, therefore, more subject to deterioration due to oxidation, etc.; and Coarse Para, which is rubber gathered from the drippings from the rubber trees after the cups have been removed. This latter grade has generally a large percentage of bark and other foreign substances mixed with it, and is subject to even more deterioration than is Medium Para, as it is oftentimes not smoked at all.

Another important grade of rubber coming from South America is Caucho. This tree grows similar to the Para trees and the rubber is gathered in a similar manner, but is cured by adding to the latex some alkaline solution and allowing the whole to dry out in the sun. The value of this rubber can be greatly improved by better methods of coagulation.

From Central America and Mexico comes the Castilloa rubber. This rubber is gathered from trees in a very similar manner to Para, and is coagulated by being mixed with juices which are obtained by grinding up a certain plant which grows in the Castilloa districts. After being mixed with this plant juice, the Castilloa is spread out in sheets on bull hides, where it is allowed to dry in the sun, after which the rubber is rolled up and is ready for shipment. Castilloa is gathered mostly from wild trees, but in Mexico it has recently been cultivated to some extent.

From Mexico we also get Guayule. This rubber is obtained from a certain species of shrub, the shrub being cut down and fed into a grinding or pebble mill where the branches are crushed and ground and mixed with water, and the rubber, which is contained in little particles all through the wood, is worked out, being taken from the pebble mills in chunks as large as a man’s fist.

From Central Africa and from Borneo come the so-called African gums, such as Congo, Soudan, Massai, Lapori, Manicoba, Pontianic, etc. Some of these rubbers are gathered from trees, but most of them from vines and roots, and the methods of coagulation are varied. Practically all of them are dried out in the sun. These rubbers are all of lower grade than the Para rubbers of South America.

[Illustration: BAGS OF CACAO BEANS.]

The Story in a Stick of Chocolate

Where Does Chocolate Come From?

Perhaps no other one thing is so well known to boys and girls the world over as chocolate. Yet there was a time, and not so many years ago, as we figure time in history, when there were no cakes of chocolate, or chocolate candies to be had in the candy shops, no chocolate flavored soda water or chocolate cake. To-day quite a panic would be started if the world’s supply of chocolate were cut off.

Chocolate is obtained from cacao, which is the seed of the cacao tree. It is quite often called cocoa, although this is not quite a correct way of spelling the word. The cacao tree grows to a height of sixteen or eighteen feet when cultivated, but to a greater height when found growing wild. The cacao pod grows out from the trunk of the tree as shown in the picture, and is, when ripe, from seven to ten inches long and from three to five inches in diameter, giving it the form of an ellipse. When you cut one of these pods open, you find five compartments or cells, in each of which is a row of from five to ten seeds, which are imbedded in a soft pulp, which is pinkish in color. Each pod then contains from twenty-five to fifty seeds, which are what we call “cocoa beans.”

The cacao tree was discovered for us by Christopher Columbus, so that we have good reason to remember him aside from his great discovery of America. The discovery of either of these would be fame enough for any one man, and it would be difficult for some boys and girls to say just which of the two was Columbus’ greater discovery.

Columbus found the cacao tree flourishing both in a wild and in a cultivated state upon one of his voyages to Mexico. The Indians of Peru and Mexico were very fond of it in its native state. They did not know the joy of eating a chocolate cream, but they had discovered the qualities of the cacao bean as a food and had learned to cultivate it long before Columbus came to Mexico.

Columbus took some of the cacao beans back with him to Spain and to this day cacao is much more extensively used by the Spaniards than by any other nation. The first record of its introduction into England is found in an announcement in the _Public Advertiser_ of June 16, 1657, to the effect that:

“In Bishopgate Street, in Queen’s Head Alley, at a Frenchman’s house, is an excellent West Indian drink called chocolate, to be sold where you may have it ready at any time and also unmade, at reasonable rates.”

Of course, by the time America became settled the people brought their taste for chocolates with them.

[Illustration: VIEW OF COCOA BEANS IN BAG AND COCOA-GRINDING MILL.]

What is the Difference Between Cacao and Chocolate?

When the cacao seeds are roasted and separated from the husks which surround them, they are called cocoa-nibs. Cocoa consists of these nibs alone, whether they are ground or unground, dried and powdered, or of the crude paste dried in flakes.

Chocolate is made from the cocoa-nibs. These nibs are ground into an oily paste and mixed with sugar and vanilla, cinnamon, cloves, or other flavoring substances. Chocolate is only a product made from cocoa-nibs, but it is the most important product.

[Illustration: CACAO CRACKING MILL AND SHELL SEPARATOR.]

[Illustration: COCOA CRACKING AND SHELL SEPARATOR.

WHERE THE SHELLS ARE SEPARATED FROM THE BEAN.]

[Illustration: COCOA MILL.]

What Are Cocoa Shells?

There are other products which are obtained from the cacao seed. One is called Broma--which is the dry powder of the seeds, after the oil has been taken out.

Cocoa shells are the husks which surround the cocoa bean. These are ground up into a fine powder and sold for making a kind of cocoa for drinking, although the flavor is to a great extent missing and it is, of course, not nearly so nourishing as a drink of real cocoa.

[Illustration: COCOA ROASTER.

MILL IN WHICH THE BEANS ARE ROASTED.]

What is Cocoa Butter?

The oil from the cacao seeds, when separated from the seeds, is what we call cocoa butter. It has a pleasant odor and chocolate-like taste. It is used in making soap, ointments, etc.

[Illustration: HOW CACAO BEANS GROW

COCOA TREE WITH FRUIT KNOWN AS COCOA PODS, WHICH CONTAIN THE COCOA BEANS.]

How is Cacao Gathered?

When the cacao pods ripen on the tropical plantations, where the climate is such that they can be grown successfully, the native laborer cuts off the ripened pods as we see him doing in the picture showing the pods on the tree. He does this with a scissors-like arrangement of knives on a long pole.

As he cuts off the pods he lays them on the ground and leaves them to dry for twenty-four hours. The next day they are cut open, the seeds taken out and carried to the place where they are cured or sweated.

In the process of curing or sweating, the acid which is found with the seeds is poured off. The beans are then placed in a sweating box. This part of the process is for the purpose of making the beans ferment and is the most important part of preparing the beans for market, as the quality and the flavor of the beans and, therefore, their value in the market, depends largely upon the ability of whoever does it in curing or fermenting.

Sometimes the curing is done by placing the seeds in trenches or holes in the ground and covering them with earth or clay. This is called the clay-curing process. The time required in curing the cacao beans varies, but on the average requires two days. When cured they are dried by exposure to the sun and packed ready for shipping. At this time beans of fine quality are found to have a warm reddish color. The quality or grades of beans are determined by the color at this stage.

[Illustration: CHOCOLATE MILL.]

How Chocolate is Made.

When the cacao beans arrive at the chocolate factory they are put through various processes to develop their aroma, palatability and digestibility.

~PROCESSES IN CHOCOLATE MAKING~

The seeds are first roasted. In roasting the substance which develops the aroma is formed. The roasting is accomplished in revolving cylinders, much like the revolving peanut roasters, only much larger. After roasting the seeds are transferred to crushing and winnowing machines. The crushing machines break the husks or “shells,” and the winnowing machine by the action of a fan separates the shells from the actual kernel or bean. The beans are now called cocoa-nibs. These nibs are now in turn winnowed, but in smaller quantities at a time, during which process the imperfect pieces are removed with other foreign substances. Cacao beans in this form constitute the purest and simplest form of cacao in which it is sold. The objection to their use in this form is that it is necessary to boil them for a much longer time, in order to disintegrate them, than when they are ground up in the form of meal. For that reason the nibs are generally ground before marketing as cacao or cocoa.

Another form in which the pure seeds are prepared is the flaked cocoa. This is accomplished by grinding up the nibs into a paste. This grinding is done in a revolving cylinder machine in which a drum revolves. In this process the heat developed by the friction in the machine is sufficient to liquefy the oil in the beans and form the paste. The oil then solidifies again in the paste when it becomes cool.

[Illustration: CHOCOLATE FINISHER.]

What we know as cakes of chocolate are made from the cocoa-nibs by heating the mixture of the cacao, sugar and such flavoring extracts as vanilla, until an even paste is secured. This paste is passed several times between heavy rollers to get a thorough mixture and finally poured into molds and allowed to cool. When cool it can be taken from the molds in firm cakes and wrapped for the market. This is the way Milk Chocolate is made. The difference in the taste and consistency of milk chocolate depends upon how many different things the chocolate maker adds to the pure cocoa-nibs to produce this mixture. Often substances such as starchy materials are added to make the cakes more firm. They add nothing to the quality of the chocolate.

[Illustration: CHOCOLATE MIXER.]

~HOW CHOCOLATE CANDIES ARE MADE~

Chocolate-covered bonbons, chocolate drops, and the many different kinds of toothsome confections are prepared in the American candy factories, as we all well know. The chocolate covering of this confectionery is generally put on by dipping the inside of the choice morsel in a pan of liquid chocolate paste and then placing the bits in tins to allow them to cool and harden.

[Illustration: CHOCOLATE MIXING AND HEATING MACHINE.]

A great many of the choicest bits of confectionery are now produced by machines entirely. These machines are almost human, apparently, as we see them make a perfect chocolate bonbon which is delivered to a candy box all wrapped for packing. These wonderful machines thus give us candy which has not been touched by the hands of any one prior to the time we thrust our own fingers in the brightly-decorated box and take our pick of the assortment it offers.

[Illustration: WHERE THE INDIVIDUAL PIECES OF CONFECTION ARE WRAPPED.]

[Illustration: THE TALLEST BUILDING IN THE WORLD

WOOLWORTH BUILDING, NEW YORK CITY.

This building, the tallest in the world, is equipped with 26 gearless traction elevators.

Two of the elevators run from the first to the fifty-first floor with actual travels of 679 feet 9¹⁄₂ inches and 679 feet 10¹⁄₄ inches, respectively. There is also a shuttle elevator which runs from the fifty-first to the fifty-fourth floor.

Total height of building from curb to base of flagstaff, 792 feet.]

[Illustration: HOW AN ELEVATOR GOES UP AND DOWN

COMPLETE GEARLESS TRACTION ELEVATOR INSTALLATION.]

How Does an Elevator Go Up and Down?

Ordinarily, when we think of an elevator we think merely of the cage or car in which we ride up or down. But the car is really only the part which makes the elevator of service to man, and from the standpoint of the machinery, is a relatively unimportant part of the equipment.

There are two principal types of elevators used to-day; the hydraulic, which is worked by water under pressure, and the electric, which is worked by electricity through an electric motor. The latter type, because of the tendency towards the general use of electricity in recent years, has largely superseded the hydraulic, and, as when you think of elevators you probably have in mind those you have seen in some huge skyscraper, we shall look at one of these.

What are the Principal Parts of an Elevator?

The most advanced type of elevator to-day is called a Gearless Traction Elevator. In this elevator the principal parts are a motor, a grooved wheel on the motor shaft called a driving sheave and a brake, all mounted on one cast-iron bed-plate; a number of cables of equal length which pass over the driving sheave and thence around another grooved wheel called an idler sheave, located just below the driving sheave, and to one end of which is attached the car or cage, and to the other end a weight called a counterweight; also a controller which governs the flow of electric current into the motor and thereby the speed, starts and stops of the elevator car. Although the controller, motor, brake and sheaves are usually placed way at the top of the building out of our sight, they are really very important parts of the elevator.

The cage or car in which we ride is held in place by tracks built upright in the elevator shaft, and the counterweight at one side of the shaft travels up and down along two separate upright tracks. When the car goes up the counterweight on the other end of the cables goes down an equal distance. The counterweight is used to balance the load of the car and to make it easier for the motor to move the car.

Electricity is the power that makes the car go up or down. The operator in the car moves a master switch--in one direction if he wishes to go up, in the other direction if he wishes to go down. This master switch sets the electro-magnetic switches of the controller at the top of the hatchway into action, electrically, and the controller in turn allows the electric current to flow into the motor. The motor then begins to revolve, gradually at first, and then faster, turning the driving sheave with which it is directly connected. As this driving sheave revolves, the cables passing over it are set in motion, and the car and counterweight to which they are attached begin to move.

Why Does Not the Car Fall?

[Illustration: THE PRINCIPAL PARTS OF AN ELEVATOR]

Of course, the question of safety is a very important one in any elevator, and you wonder what would happen if the cables broke. You think of this especially when you are going up in one of the big skyscrapers--where the elevators sometimes travel to a height of 700 feet. It can be truthfully said that on every modern elevator there are safety devices which should make it practically impossible to have a serious accident, due to the fall of the car. Every elevator is equipped with wedging or clamping devices which automatically grip the rails in case the car goes too fast either up or down. These gripping devices can be adjusted to work at any speed that is desired above the regular speed. It is not at all probable that all the cables will break at once, because there are usually six of these, and any one of them is strong enough to hold the car if the others break; but even if they all should break the gripping devices on the rails will operate and hold the car safely, just as soon as it starts down at great speed.

Suppose that the car should descend at full speed, but not sufficiently fast to work the rail-gripping devices, it would be brought to a gradual rest at the bottom of the hatchway, because of the oil-cushion buffer against which it would strike. This is a remarkable invention, with a plunger working in oil in such a way that a car striking it at full speed will come to rest so gradually that there is scarcely any shock. You have perhaps seen a clever juggler on the stage throw an ordinary hen’s egg high into the air and catch it in a china dish without cracking it He does it by putting the dish under the falling egg just at the right moment, and bringing the dish down with the egg at just the right speed, so that eventually he has the egg in the dish without cracking it. The trick is in calculating the rate of speed of the falling egg accurately and adjusting the insertion of the dish under the falling egg to a nicety. The oil-cushion buffer in the modern elevator works in very much the same way.

[Illustration: GENERAL ARRANGEMENT OF ROPING FOR GEARLESS TRACTION ELEVATOR INSTALLATION.]

If it were not for the genius which has made possible these new types of elevators we could not have the high buildings. The elevators in the Woolworth Building are the latest type in modern elevator construction. In this one building alone there are 29 elevators, and when you are told that the electric elevators in the United States installed by a single company represent a total of 525,000 horse-power, you will have some idea of the power required to operate elevators all over the country.

Does Air Weigh Anything?

Air is very light, so light that it seems to have no weight at all; but, if you will think a minute you will see that it must have some weight, because birds fly in it and balloons can be made to float through it. It has been found that one hundred cubic inches of air at the sea level weighs, under ordinary conditions, about thirty-one grains. This seems a very small weight, but when we remember the thickness of the atmospheric envelope over the earth we see that it must press quite heavily upon the earth’s surface. There is a very simple instrument called a barometer, which is used for measuring the amount of this pressure. The name means pressure-measure.

Another striking feature of air is its elasticity, and this explains something that is noticed by all mountain climbers. On a high mountain, it is difficult to get enough air to the lungs, though one breathes rapidly and deeply. The reason is, that the air at the foot of the mountain is compressed by the weight of that above it, and consequently the lungs can hold more of it than of the air on the mountain top, which has less weight resting upon it and is, therefore, not so much compressed. On account of the ease with which it is compressed, we find that more than half of all the envelope of air that surrounds the earth is within three miles of the surface.

When air is chemically analyzed it is found to consist of a number of substances mingled together, but not chemically united. These include nitrogen, oxygen, argon, carbonic acid gas, water vapor, ozone, nitric acid, ammonia, and dust.

Oxygen is the most important of these constituents, for it is the part that is necessary to support life. Yet, notwithstanding its importance, it forms only about one-fifth of the entire bulk of the atmosphere.

Oxygen is a very interesting substance and many striking experiments may be performed with it. If a lighted candle is thrust into a vessel filled with oxygen, it burns very much more rapidly and brilliantly than in air. A piece of wood with a mere spark on it bursts into flame and burns brightly when thrust into oxygen, and some things that will not burn at all in air, can be made to burn very rapidly in oxygen. For example, if a piece of clock spring be dipped in melted sulphur and then put into a jar of oxygen, after the sulphur has been set on fire, the steel spring will take fire and burn fiercely. The heat produced is so great that drops of molten steel form at the end of the spring, and falling on the bottom of the jar, melt the surface of the glass where they strike.

The other two substances found in pure air, nitrogen and argon, are very much alike. They make up the remaining four-fifths of the air, and are very different from oxygen in nearly every respect.

Nitrogen and argon resemble oxygen in being colorless, odorless, and tasteless gases; and they are of nearly the same weight as oxygen, argon being a little heavier and nitrogen a little lighter; but here the similarity ends. Oxygen is what we call a very active substance. As we have seen, it causes things to burn very much more rapidly in it than in air. Nitrogen and argon, on the contrary, put out fire. If a lighted candle is put into a jar of nitrogen or argon its flame will be extinguished as quickly as if put into water.

We must now consider the impurities found in air. Of these the most important is carbonic acid gas, or, as it is frequently called, carbon dioxide. It is always produced when wood or coal is burned, and is, of course, constantly being poured out of chimneys. It is also produced in our lungs and we give off some of it when we breathe. It is colorless, like the gases found in pure air, has no odor or taste, and is considerably heavier than oxygen or nitrogen. In its other properties it is much more like nitrogen than oxygen, for when a candle is put into it the flame is extinguished at once. To find out whether air contains carbonic acid gas, it is only necessary to force it through a little lime water, in a glass vessel, and watch what change takes place in the water. Fresh lime water is as clear as pure water; but after forcing air containing carbonic acid through it, it becomes turbid and milky. If the turbid water is allowed to stand for a time, a white powder will settle to the bottom, and if we examine this powder, we find it to be very much the same thing as chalk. While it is true that air generally contains only a very small portion of carbonic acid gas, there are some places in which it is present in such large quantities as to render the air unfit for breathing. The air at the bottom of deep mines and old wells often has an unusually large proportion of this gas, which, because of its great weight, accumulates at the bottom, and remains confined there. The presence of a dangerous quantity of the gas in such places may be detected by lowering a candle into it.