Chapter 8

After all said and done, however, the reactions taking place, although they have an intense fascination for the chemist, are not the factors which the gas manager deems the most important, the cost of any given process being the test by which it must stand or fall; and it will be well now to consider, as far as it is possible, the expense of enriching coal gas by the various methods I have brought before you.

In order to be well above the prescribed limit of illuminating power at all parts of an extended service, the gas at the works must be sent out at an illuminating power of 17.5 candles and we may, I think, fairly take it that 16 candle coal gas, as made by the big London companies, costs, as nearly as can be, 1s. per 1,000 cubic feet in the holder, and the question we have now to solve is the cost of enriching it from 16 to 17.5 candle power. When this is done by cannel, the cost is 2.6 pence per candle power, so that the extra 11/2 would cost 4d. per 1,000.

Carbureting by the vapors of gasoline by the Maxim-Clarke process costs 13/4d. per 1,000, so that the extra candle power would mean an expenditure of 2.62 d. Unfortunately I have no figures upon which to calculate the cost of producing such a gas by the Dinsmore process, but with the three important water gas enrichers we can deal.

Using Russian fuel oil, which can be obtained in bulk in London at 3d. per gallon, the proprietors of the Springer plant guarantee 51/2 candle power per 1,000 cubic feet of gas per gallon used, so that, to produce a 22 candle gas, 4 gallons would be used. The cost per 1,000 cubic feet may be roughly tabulated, as the coke used amounts to about 40 lb.

s. d. Oil.................................... 1 0 Coke................................... 0 3 Labor and purification................. 0 2 Charge on plant........................ 0 1 ---- 1 6

Twenty five per cent. of 12-candle gas when mixed with 75 per cent. of the 16-candle gas gives the required 17.5 candle gas, which would therefore cost 1s. 11/2d., or the enrichment would have cost 11/2d.

By the Lowe process, an increase of 5.3-candle power is guaranteed for the consumption of a gallon of the same oil, so that the cost would be a shade higher, all other factors remaining the same, while with the Van Steenbergh process both grade of oil and consumption of fuel vary from either of these processes. In order to obtain a thousand cubic feet of 22-candle gas, two and a half gallons of the lighter grade oil would be consumed, and I am informed that there is now no difficulty in obtaining oil of the right grade in London in bulk at 4d. per gallon, which would make the cost:

s. d. Two and a half gallons of oil........... 0 10 Thirty pounds of coke................... 0 21/4 Labor and purification.................. 0 2 Charge on plant......................... 0 03/4 ------ 1 3

And the enriched coal gas would, therefore, cost 1s. 3/4d. per thousand, the extra 11/2-candle power having been gained at an expense of 3/4d. or 1/2d. per candle.

Tabulating these results we have--Cost of enriching a 16-candle gas up to 17.5 candle power per 1,000 cubic feet by cannel coal, 4d.; by Maxim-Clarke process, 2-6/10d.; by Lowe or Springer water gas, 11/2d.; by Van Steenbergh water gas, 3/4d.

In reviewing this important subject, and bringing a wide range of experimental work to bear upon it, I have, as far as is possible, divested my mind of bias toward any particular process, and I can honestly claim that the fact of the Van Steenbergh process showing such great superiority is due to the force of carefully obtained experimental figures, corroborated by an experienced and widely known gas chemist, and by the chief gas examiner of the city.

In adopting any new method, the mind of the gas manager must to a great extent be influenced by the circumstances of the times, and the enormous importance of the labor question is a main factor at the present moment; with masters and men living in a strained condition which may at any moment break into open warfare, the adoption of such water gas processes would relieve the manager of a burden which is growing almost too heavy to be borne.

Combining, as such processes do, the maximum rate of production with the minimum amount of labor, they practically solve the labor question. Requiring only one-tenth the number of retort house hands that are at present employed, the carbureted water gas can be used for enrichment until troubles arise, and then the gas can be used pure and simple, with a hardly perceptible increase in expense, while the rapidity of make will also give the gas manager an important ally in the hour of fog, or in case of any other unexpected strain on his resources.

One of the first questions asked by the practical gas maker will be: "What guarantee can you give that as soon as we have erected plant, and got used to the new process of manufacture, a sudden rise in the price of oil will not take place, and leave us in worse plight than we were before?" and the only answer to this is that, as far as it is possible to judge anything, this event is not likely to take place in our time. A year ago the prospects of the oil trade looked black, as the output of American oil was in the hands of a powerful ring, who seemed likely also to obtain control of the Russian supplies; but, fortunately, this was averted, and, at the present moment, the Russian pipe lines are flooding the market with an abundant supply, which those best able to judge tell us is practically inexhaustible, so that prices may be expected to have a downward rather than an upward tendency. But even should a huge monopoly be created, I think I have found a source of light at home which will hold its own against any foreign illuminant in the market.

For a long time I have felt that in this country we had sources of light and power which only needed development, and the discovery of the right way to use them, in order to give an entirely new complexion to the question of carbureting; and now by the aid of the engineering skill and technical knowledge of Mr. Staveley, of Baghill, near Pontefract, I think it is found.

At three or four of the Scotch iron works the Furnace Gases Co. are paying a yearly rental for the right of collecting the smoke and gases from the blast furnaces. These are passed through several miles of wrought iron tubing, diminishing in size from 6 feet down to about 18 inches; and as the gases cool, so there is deposited a considerable yield of oil.

At Messrs. Dixon's, at Glasgow, which is the smallest of these installations, they pump and collect about 60,000,000 cubic feet of furnace gas per day; and recover, on an average, 25,000 gallons of furnace oils per week, using the residual gases, consisting chiefly of carbon monoxide, as fuel for distilling and other purposes, while a considerable yield of sulphate of ammonia is also obtained. In the same way a small percentage of the coke ovens are fitted with condensing gear, and produce a considerable yield of oil, for which, however, there is a very limited market, the chief use being for lucigen and other lamps of the same description, and for pickling timber for railway sleepers, etc.; the result being that, four years ago, it could be obtained in any quantity at 1/2d. per gallon, while since that it has been as high as 21/2d. a gallon, but is now about 2d., and shows a falling tendency. Make a market for this product, and the supply will be practically unlimited, as every blast furnace and coke oven in the kingdom will put up plant for the recovery of the oil, and as with the limited plant now at work it would be perfectly easy to obtain 4,000,000 or 5,000,000 gallons per annum, an extension of the recovery process would mean a supply sufficiently large to meet all demands.

Many gas managers have, from time to time, tried if they could not use some of their creosote for gas producing, but on heating it in retorts, etc., they have found the result has generally been a copious deposit of carbon, and a gas which has possessed little or no illuminating value. Now, the furnace and coke oven oils are in composition somewhat akin to the creosote oil, so that at first sight it does not seem a hopeful field for search after a good carbureter, but the furnace oils have several points in which they differ from the coal tar products. In the first place, they contain a certain percentage of paraffin oil, and in the next, do not contain much naphthalene, in which the coal tar oil is especially rich, and which would be a distinct drawback to their use.

The furnace oil as condensed contains about 30 to 50 per cent. of water, and in any case this has to be removed by distilling; and Mr. Staveley has patented a process by which the distillation is continued after the water has gone off, and by condensing in a fractionating column of special construction, he is able to remove all the paraffin oil, a considerable quantity of cresol, a small quantity of phenol, and about 10 per cent. of pyridine bases, leaving the remainder of the oil in a better condition, and more valuable for pickling timber, which is its chief use.

If the mixed oil so obtained, which we may call "phenoloid oil," is cracked by itself, no very striking result is obtained, the 40 percent. of paraffin present cracking in the usual way, and yielding a certain amount of illuminants, but if this oil be cracked in the presence of carbon, and be made to pass over and through a body of carbon heated to a dull red heat, then it is converted largely into benzene, the most valuable of the illuminants, and also being the one to which coal gas owes the largest proportion of its illuminating power, it is manifestly the right one to use in order to enrich it.

On cracking the phenoloid oil, the paraffins yield ethane, propane, and marsh gas, etc., in the usual way, while the phenol interacts with the carbon to form benzene--

Phenol. Benzene. C6H5HO + C = C6H6 + CO.

And in the same way the cresol first breaks down to toluene in the presence of the carbon, and this in turn is broken down by the heat to benzene.

A great advantage of this oil is that the flashing point is 110, and so is well above the limit, thus doing away with the dangers and troubles inseparable from the storage of light naphtha in bulk.

In using this oil as an enricher, it must be cracked in the presence of carbon, and it is of the greatest importance that the temperature should not be too high, as the benzene is easily broken down to simpler hydrocarbons of far lower illuminating value. This fact is very clearly brought out by a series of experiments I have made, in which the phenoloid oil was cracked by passing it through an iron tube packed with coke and heated to various temperatures, the hydrocarbons being much more easily broken up under these conditions than if mixed with diluents, such as water gas:

RESULTS OBTAINED ON CRACKING PHENOLOID OIL.

I. II. III.

Temperature. 600° C. 800° C. 1,000° C. Volume of gas per gallon. 41.6 c.f. 76.8 c.f. 121.6 c.f.

COMPOSITION OF THE GAS.

Hydrogen. 34.0 36.0 37.0 Methane. 20.0 26.0 49.0 Olefines. 11.0 5.0 Nil. Ethane. 16.0 9.0 Nil. Carbon monoxide. 13.0 15.0 12.0 Carbon dioxide. 2.0 4.0 2.0 Oxygen. 2.0 1.0 Nil. Nitrogen. 2.0 4.0 Nil.

This analysis shows that if the temperature is allowed to reach a cherry red, complete decomposition of the illuminating hydrocarbons is taking place, and a gas of practically no illuminating value results. The power of regulating the temperature and the body of carbon as a cracking medium in the Van Steenbergh water gas plant especially fits it for using this oil, and removes the objections which could have been urged against the lighter naphthas.

This oil is at present not in the market, but given a demand, it can be produced in four months, at the latest, in very large quantities, as the apparatus is very easy and cheap to erect, and the crude material can be plentifully obtained.

If this oil becomes, as I think it will, an important factor in the illumination of the future, it will mark as important an era in the history of our industries as any which the century has seen, as, by using it, you are giving smoke a commercial value, and this will do what the Society of Arts and the County Council have failed in--that is, to give us an improved atmosphere. If I were lecturing on an imaginary "Hygeia," I should point out that the smoke of London contains large quantities of these oils, and they, by coating the drops of mist on which they condense, give the fog that haunts our streets that peculiar richness which is so irritating and injurious to the system, and, further, by preventing the water from being again easily taken up by the air, prolong the duration of the fog. Make this oil a marketable commodity, and another twenty years will see London without a chimney; underground shafts will be run alongside the sewers; into these shafts by means of a down draught all the products of combustion from our fires will be sucked by local pumping stations, and the oil condensing in the tubes will serve in turn to illuminate our streets, instead of performing its former function of turning day into night and ruining our health; but as I am not at all sure of the engineering possibilities of such a scheme, I will leave its discovery to some other abler prophet than myself.

(_To be continued_.)

* * * * *

ELECTRICAL LABORATORY FOR BEGINNERS.

BY GEO. M. HOPKINS.

It is only when theory and practice, study and experiment, go hand in hand that any true progress is made in the sciences. A head full of theory is of little value without practice, and although the student may apply himself with all his energies for years, his time will, to a great extent, have been spent in vain, unless he by experiment rivets the ideas he gains by his study.

In the study of electricity, for example, let the student try to remember the position a magnetic needle will take when placed below or above a conductor carrying a current which flows in a known direction. Without experiment there are nine chances of forgetting to one of remembering; but let the student try the experiment, and he will ever afterward be able to determine the direction in which the current is flowing by the position taken by the needle relative to the conductor.

In the matter of ampere turns, as another example, it is quite simple to assert that a ten ampere current carried once around a soft iron bar produces the same result as a one ampere current carried ten times around the bar, but how much more strongly is this fact stamped upon the memory when its truth is established by experiment?

Reading about a fact, or commiting to memory the literature of a subject, is desirable and even necessary, but knowledge of this character partakes more of the nature of faith than that gained by actual experience.

Let the reader learn first all that can be learned by the aid of this simple apparatus, then branch out to allied things, making each step as thorough as possible, and before long he will be congratulating himself on having gained at least an elementary knowledge of electricity.

Very little can be done in the way of electrical experiment without an electrical generator of some sort, and nothing at present known can excel a battery for this purpose. Although not the most desirable battery for all purposes, that shown in Fig. 1 is the most desirable for the amateur who desires a strong current for a short time. It is formed of two plates, a, of carbon arranged on opposite sides of an amalgamated plate, b, of zinc, and separated from the zinc by strips of wood. Bars of wood are placed outside of the carbon plates, and the four bars are fastened together by two common wood screws, thus clamping all the bars and the zinc and carbon plates securely in the position of use.

Between the zinc plate and the wooden bar adjoining it is inserted a strip of copper, c, for leading away the current from the zinc pole of the battery, and between the carbon plates and the wooden bars is inserted a doubled strip of copper, d, forming a connection between the two carbon plates, and at the same time serving as a conductor for conveying away the current from the carbon pole of the battery. This element is to be plunged into a tumbler of sufficient depth to allow the wooden bars to rest on the upper edge of the tumbler, while the lower ends of the plates are one-half or three-quarters inch above the tumbler bottom.

THE SOLUTION.

In the tumbler is placed a solution consisting of two-thirds of a tumblerful of water, two ounces of bichromate of potash, and two ounces of sulphuric acid. The bichromate of potash should be dissolved first, then the acid should be slowly and carefully added. As the solution heats, it is well to prepare it in an earthen vessel, which is not liable to break. These materials should be used with great caution, as they are poisonous, and the solution is very corrosive, destroying almost everything with which it comes in contact. With proper care, however, there is no danger in using the solution. It gives off no poisonous vapors. Of course it is advisable to make the solution in quantities of a gallon or so when convenient.

The battery compound known as the C and C battery compound, sold in tin cans at most electric stores, is very convenient. It is only necessary to place two or three ounces of it in the tumbler and add the amount of water above mentioned, stirring the solution with a glass or rubber rod until the crystals are dissolved.

A caution is necessary here. If only a portion of the contents of the can are to be dissolved, it will be necessary to place the remainder in a glass or earthen jar, as it will absorb moisture and rapidly eat its way through the can.

The zinc plates should be amalgamated by plunging them into the bichromate solution, then sprinkling on a minute quantity of mercury, rubbing it about by means of a swab, until the entire exposed surface is covered with mercury.

CONVENTIONAL SIGN FOR THE BATTERY AND GALVANOMETER.

In making electrical diagrams it is necessary to frequently represent a battery. It requires too much time to make a sketch or drawing of a battery. Besides this, the drawing of any particular kind of battery might be misleading. A sign representing the galvanic battery has been universally adopted. It consists of a long, thin mark or dash, representing the carbon electrode, and a shorter, thick mark representing the zinc electrode, thus: [Illustration] Where more cells are required, this sign is repeated once for each cell, thus: [Illustration] The galvanometer is represented thus: [Illustration]

By the use of the battery and a few articles such as may be found anywhere, in addition to the pieces shown in Fig. 2, all the experiments here described may be performed. As these pieces are shown half size in the diagrams, Fig. 2, and about full size in the perspective views, it will be unnecessary to give dimensions. The bobbins, A A, are wound with No. 24 double cotton-covered magnet wire, the terminals being soldered to eyes formed of pieces of spring wire bent so as to form helical coils of two turns each, with the ends inserted in holes drilled in heads of the spools. These coiled wires answer a good purpose in making electrical connections. The magnet frame, B, consisting of the cores and the yoke formed integrally of a single soft gray iron casting, is adapted to receive the bobbins, A A, to form an electro-magnet. The yoke of the magnet is provided with a thumb-screw, e, for securing the magnet to the motor frame, C. The latter is furnished with a base piece, f, a slotted standard for receiving the clamping screw, e, of the magnet, and the standards, g, in which is journaled the armature, h, on a wire extending through both the standards and the armature.

The armature, h, consists of an oblong rectangular soft iron frame having at one end a small pulley and at the other end an elliptical boss, i, which is arranged obliquely to form in conjunction with the spring, j, a circuit closer and opener, which closes the circuit twice during each revolution of the armature, just as one of its side bars is approaching the poles of the magnet and breaks it as the bar comes opposite the poles of the magnet.

The spring, j, is bent into a loop and its lower end is inserted in a wooden plug driven into a hole in the base piece, f.

In the upper part of Fig. 2 are shown two telegraph instruments less the bobbins. Each instrument (Fig. 14) consists of a wooden base, k, a right angled soft iron bar, l, having the central part of its upper end brought to an obtuse angle, an armature, m, fitted loosely to the angled end of the bar, a notched brass standard, n, for limiting the movement of the armature, a retractile spring for lifting the armature, a spring key, o, pivotally secured to the base by a common wood screw, and a contact point projecting from the base under the key.

Besides these there is a D shaped block, to answer as a frame to the galvanometer, a common pocket compass, E, fitted to a circular cavity in the top of the block, D, a permanent U magnet, F, a bundle of soft iron wires, G, and two copper strips, H.

DECOMPOSITION OF WATER.

To illustrate the decomposition of water, connect the copper strips, H H, to the poles of the battery by means of wires, as shown in Fig. 3, and insert them in a tumbler of water acidulated with a few drops of sulphuric acid. Instantly bubbles will rise from the copper strips, showing that gas is being disengaged from the water. The strip connected with the carbon plate will disengage oxygen, while the strip connected with the zinc plate will disengage hydrogen.

SOLENOID.

By connecting one of the coils, A, with the battery by means of the wires, the action of a helix or solenoid is shown. When so connected, the helix will draw up with itself a barrel pen, or any light iron or steel object. (See Fig. 4.) This is not a true solenoid, but it is generally known by that name. In a true solenoid one of the terminals is passed back through the center of the coil.

MAGNETIZATION OF STEEL.

By inserting in the solenoid a knitting needle, or any bar of hardened or tempered steel, and sending a current through the coil, the steel will become permanently magnetized.

ELECTROMAGNET.

By placing the two coils, A, upon the magnet frame, B, and connecting one terminal of each with the battery, the remaining terminals being connected together, as shown in Fig. 5, an electromagnet is formed which will lift several pounds.

ELECTRIC MOTOR.

By placing the magnet thus formed upon the motor base, C, in front of the armature, h, as shown in Fig. 6, and connecting one terminal of the magnet with the battery and the other with the clamping screw, e, of the magnet, and by connecting the commutator spring, j, with the remaining pole of the battery, the motor will be made to rotate rapidly.

COMPASS AND MAGNETIC EXPERIMENTS.