Where Did the Word “Gas” Originate?
A Belgium chemist, Van Helmont, coined the word “gas” in the first half of the seventeenth century. The Dutch word “geest,” signifying “ghost,” suggested the term to him, and his superstitious neighbors hounded him into obscurity for talking of ghosts.
Hanging lamp from Nushagak in Southern Alaska. It is suspended from the framework of the tent by cords. Oils and fats from northern animals give a clear and steady light, and Eskimo lamps are frequently praised by travelers.
WHAT THE BIG TANK NEAR THE GASWORKS IS FOR
SIX MILLION CUBIC FOOT GAS HOLDER.
Almost every boy and girl has seen the big tank near the gas works, and most of them have wondered what was in it and what it is for. This big tank is a “holder” in which the gas is stored after it is manufactured.
The giant holders are reservoirs from which gas is constantly being taken and the quantity on storage constantly replenished, as the ordinary gas plant never ceases manufacturing its product.
There is little or no danger of an interruption of the supply by reason of accident, as gas plants are always equipped with duplicate apparatus for emergencies.
When Illuminating Gas Was Discovered
The first practical demonstration of the value of gas made from coal for lighting was made by a Scotchman—Robert Murdock—who in 1797, after some years of experimenting, fitted up an apparatus in the workshop of Boulton and Watt, in Birmingham, England, which successfully lighted a portion of that establishment. The advantages of this kind of lighting were so apparent that its use was rapidly extended, although in many instances the people were afraid of it. For a time this kind of lighting was confined to street lights. One of the first great structures to be lighted by gas was Westminster Bridge in London, and great crowds gathered to watch the burning jets nightly. It was difficult to remove from the minds of the people the belief that the gas-pipes were filled with fire and the jets were only openings through which the flame in the pipes escaped. People sometimes touched the pipes expecting to find them hot, and when the pipes were put in buildings they made sure that they were placed several feet from the walls lest the fire in them set fire to the buildings.
The use of illuminating gas for lighting private houses developed quite slowly because of this fear of the fire in the gas-pipes. This was not entirely unwarranted, however, because at first the plumbers did not know, as they do now, how to prevent leakage of gas from the pipes. The methods of joining the pipes were oftentimes imperfect and, not realizing the dangers which would follow leaks, causing explosions, the workmen were often careless in installing the pipes.
The first American house in which gas was used for lighting was the home of David Mellville at Newport, R. I. Baltimore, Maryland, was the first American city to use gas for lighting. It was introduced there in 1817.
How Does Gas Get Into the Gas Jet?
If you hold a cool drinking glass over a burning gas jet for a moment, a film of moisture will form on the inside of the glass and remain until the tumbler becomes warm, and then disappear. Now, then, you will remember that water is a mixture of oxygen and hydrogen, and that when hydrogen is burned in the air, water is formed. It is also true that whenever water is formed by burning anything, hydrogen is present in it. You see, therefore, that the gas used for lighting purposes must contain hydrogen.
Let us now learn something more about what gas is made of. Wet a piece of glass with a little fresh lime water and hold this over the lighted gas jet. In a few moments a change takes place in the water. The water turns somewhat milky. This indicates the presence of carbonic acid gas, and the formation of carbonic acid gas, when burning is going on, means the presence of carbon.
From these two experiments we gather that the gas in the jet contains hydrogen and carbon. All kinds of illuminating gas contain these two substances. Sometimes there are small quantities of other substances present, but the value of gas for lighting depends on hydrogen and carbon.
We have already learned about hydrogen, but it would be well to re-learn about carbon.
Carbon is an element, and an extremely important one, for a large part of the composition of every living thing is carbon. It is found in more compounds than any other element. Almost pure carbon can easily be obtained by heating a piece of wood, in a covered utensil, until it is turned into charcoal. Charcoal, which is black, is composed almost entirely of carbon. It is a very interesting product in all ways; in connection with gas we are particularly interested in the fact that carbon will burn when heated in the air or in oxygen.
Charcoal is very much like hard coal, both being formed in practically the same way. Ages of years ago many large forests of trees were buried under a layer of soil and rocks, during changes that occurred in the earth’s surface, and the hot inside earth slowly heated the wood, until almost nothing was left but the carbon.
WHERE THE GAS IS TAKEN FROM THE COAL
GENERATOR HOUSE AND 175-FT. STACK.
In the process of gas making, coal is placed in the generator and heated to an incandescent state, then from the top or bottom steam is admitted and forced through the heated coal, producing a crude water gas which is passed on to the carbureter. In this shell enriching oil is produced, but as the oil and the water gas do not effectually unite, they are passed on to the superheater, where, as its name implies, they are subjected to a high temperature which thoroughly gasifies them into a permanent gas.
AN INTERIOR VIEW OF GENERATOR HOUSE.
* Pictures on Gas Manufacture by courtesy of the Consolidated Gas, Electric Light and Power Co. of Baltimore.
ILLUMINATING GAS MUST BE SCRUBBED
SHAVING SCRUBBERS.
After passing into the scrubbers the gas is cooled, passed into the scrubbers, and by contact with wooden slat trays, made up like screens; a large portion of the tar is removed from the gas, the tar passing off to large receptacles.
Soft coal was formed in much the same manner, but the process was not so completely finished. Mixed with the carbon in soft coal we find quite a good deal of other substances, of which hydrogen forms the principal part. This is what makes soft coal valuable in the making of illuminating gas.
When soft coal is heated in a closed receptacle a gas is formed which will burn. To show this we have only to take an ordinary clay pipe, put a little piece of coal in the bowl, close the top with wet clay, and put the bowl part of the pipe in the fire. When it is quite hot, a gas will be found coming out of the stem of the pipe, which will, when lighted, burn.
The Story in a Gas Jet
HOW ILLUMINATING GAS IS MADE
Soft coal is heated in large tubes of fire clay called retorts, and the gas that is formed is then collected in a large tank and sent through pipes to our homes after being purified. The part of the coal that is left consists largely of carbon and is what we call coke.
While the gas that comes directly from coal will burn if lighted, it is not a desirable gas to burn in our homes, because it contains a number of substances that should be eliminated before it is used for lighting.
How the Gas Is Purified
From the clay retorts the gas passes through horizontal pipes containing water. This cools it and takes out of it most of the tar and water vapor that are driven off with the gas when formed. These substances settle in the water. The gas then goes through a series of curved pipes, which are air cooled. These pipes constitute what is known as an atmospheric condenser. From these the gas goes into a series of receptacles containing wooden slat trays, made up like screens. These receptacles are called the scrubbers, and they take out of the gas the last traces of tar and some of the other compounds found present. The removal of the sulphur is very important, for burning sulphur gives off a gas which is not only extremely impure to breathe, but also injurious to the health.
From the scrubbers the gas goes on through pipes to the purifiers—boxes which contain wood shavings coated with iron rust upon which the sulphur is deposited by chemical action. At the same time the lime absorbs a small quantity of carbonic acid gas, which is formed with the other gases. From the purifiers the gas passes into the great iron tanks, in which it is stored until needed.
The gas in the tanks consists chiefly of hydrogen, a number of compounds of hydrogen and carbon, and a small amount of a compound of carbon and oxygen containing less oxygen than carbonic acid gas, known as carbon monoxide. The hydrogen and carbon monoxide burn with a very pale flame, which gives but little light and much heat. The light-giving quality of the gas is found in the compounds of carbon and hydrogen. When these burn, the particles of carbon are heated white hot and glow very brightly, making a luminous flame.
There are, of course, some impurities in the purified gas. These are compounds containing sulphur and ammonia. The quantities of these substances, however, are so small that they are harmless; but the compounds taken out in the process of purifying the gas are saved, as considerable use is made of them. The water used for washing the gas is heavily charged with ammonia and is, in fact, the chief source of the ammonia sold by druggists.
HOW THE IMPURITIES ARE TAKEN FROM THE GAS
PURIFYING BOXES.
The principal impurity to be removed is sulphur, and this is accomplished by passing the gas through large iron rectangular boxes filled with wood shavings coated with iron rust upon which the sulphur is deposited by chemical action.
STATION METER HOUSE, SHOWING CONSTRUCTION OF TWO NEW 13-FT. METERS.
HOW THE METER MEASURES THE GAS
Gas first enters inlet pipe A (Fig. 3) passing along A1 into covered valve chamber B up through orifice O. It then passes down through two of the valve ports at the same time, ports C and D1 (Fig. 2). Before C1 (Fig. 3) has gotten to its extreme opening, the valve on the opposite side has moved to allow gas to pass down port D. On every quarter turn of tangent P, one port is opening to receive gas which passes down through the valve ports into the chambers below (see arrows on Fig. 2), which shows the gas passing into chamber F. The pressure being greater on the outside of the diaphragm, forces the diaphragm inward and expels the gas from the inside of D2 through D and passes over the cross-bar into the fork channel (see Fig. 1). On the other side gas is passing down through port D1 (Fig. 2) entering diaphragm D3, the pressure being greater on the inside of D3 therefore forces the diaphragm outward and expels the gas from the outside of diaphragm D3; out through port C1 into fork channel same as shown in (Fig. 1). All exhaust gas from the chambers below is checked from entering the chamber B by the slide valve G and G1 (Fig. 2). Instead of passing into chamber B it passes over the cross-bars between D1E1 and C1E1 into the fork channels, then to outlet pipe N (Fig. 3) to house pipe.
Note: All gas registered must pass through outlet N.
In addition to coal gas made in the way just described, there is another form of illuminating gas, in the manufacture of which coal is indirectly employed. This gas, known as water gas, because it is formed by the decomposition of water, is produced by passing steam over red hot carbon, in the form of hard coal or coke. When this is done, the hydrogen in the steam is set free and the oxygen combines chemically with the carbon, to form the carbon monoxide, that was mentioned as being present, in small proportions, in ordinary coal gas. This carbon monoxide is poisonous, if much of it is breathed, and as it has no odor it is difficult to detect when escaping. A number of deaths have resulted from water gas for this reason, and in some states the laws forbid its use for lighting purposes.
When water gas is used it must be enriched with some other substances before it will yield much light. You have already learned that neither hydrogen nor carbon monoxide burns with a bright flame, and you will see that water gas must have something added to it to fit it for lighting purposes. The substance usually added is the vapor of some light, volatile oil, like gasoline. This vapor is composed of compounds of carbon and hydrogen, and when it is mixed with the water gas it forms a gas that yields a very satisfactory light; and that may be produced more cheaply than common coal gas.
There remains one more form of illuminating gas which has been the subject of much discussion in recent years, namely, acetylene. This is a compound of carbon and hydrogen, in which there is twelve times as much carbon as hydrogen. It has not been discovered recently, for it was known early in the nineteenth century, but its possible use for lighting purposes was not considered then.
Attention was directed to it a few years ago by the discovery of a substance called calcium carbide. This is a compound of carbon and the metal calcium, formed by heating to a very high temperature a mixture of coal and lime. It has the peculiar property of decomposing, when treated with water. The calcium present combines with the oxygen and half the hydrogen of the water, to form common slacked lime or calcium hydrate, while the carbon and the remainder of the hydrogen combine to form acetylene gas.
The gas formed in this way needs no purifications before burning; it can be produced in small generators, and the production can be checked at any time. When burned in the proper form of burner it yields the brightest of all gas flames. For these reasons it is adapted for use in small villages and for lighting single houses. It is also frequently used in magic lanterns, where a strong and steady light is necessary. But the cost of producing acetylene in large quantities is greater than that of coal gas, and it seems extremely unlikely that it will ever be much used for lighting large cities and towns.