The recovery of benzol is every whit as essential to the community of these islands as is the provision of drinking water. It may appear to be Draconic to compel the delivery of the last ounce of benzol from the coal or gas we burn, but there are many other enactments in force of a more exasperating character, and which are productive of extremely little benefit either to the individual or the community. In this particular instance no one would suffer in any way, because, while the whole trend of scientific thought is towards the thorough recovery of this valuable liquid fuel and industrial weapon, it does not hesitate to demonstrate how the desired end can be obtained without inflicting the slightest hardship upon the citizen.
The steel trade demands huge quantities of coke to conduct its operations. The carbon residue from coal is preferable to the raw mineral fuel. To meet this technical requirement special ovens have had to be evolved to turn the coal into coke. Yet for years we carried out this conversion and allowed the substance thrown off in the process to run to waste. We even continue to do this to-day. It was found that the coke could be obtained more readily and easily, as well as cheaply, by means of what is known as the bee-hive oven. This coke-producer attracted the attention of the interests concerned because it was not only cheap to install but inexpensive to maintain and renew, while it facilitated compliance with the fluctuating demands for the coke which naturally is due to the alternating periods of depression and prosperity in the steel trade. But we have no monument to waste comparable with the bee-hive oven. However, it became so firmly entrenched as to prove wellnigh resistant to progress when science came along with an improved system yielding a coke of equal quality, but which had the additional recommendation of enabling all the other products arising from distillation and which formerly were permitted to escape, to be recovered.
The virtues of the new method were conceded, but the heavier initial expenditure which it entailed was regarded as an insurmountable adverse feature, especially as the Britisher gave expression to another peculiar trait in his character—would the revenue derived from the by-products more than offset the increased costs, capital charges and maintenance expenses? One disturbing factor demanded particularly careful study. When the call for coke declines, and a certain number of the ovens have to be closed down, they cannot be brought into re-activity upon the revival in the steel trade without an overhaul.
In restoring the ovens heavy expense is incurred. The antiquated and wasteful bee-hive oven can be renovated at a trifling price, but the modern by-products recovery oven entails far heavier expense before the resumption of operations. The charge varies according to the care which has been bestowed upon its maintenance, but, if this has not been conducted along careful lines it may easily incur an expenditure ranging up to 15 per cent. of the original cost of the plant. This charge, unless defrayed out of the renewals account, must be carried to capital. In view of this circumstance the general practice has been to install the by-product system to take care of the constant load—the output of coke to the degree below which it cannot fall even in periods of extreme depression—and to utilize the obsolete bee-hive oven to take care of the fluctuations from the irreducible minimum to the maximum. This margin being extremely wide naturally, the bee-hive still holds sway, and so continues its wasteful reign unchecked.
To extend their field of activity and to provide an outlet for the products of their brains the Germans made an astute commercial move. They expressed their readiness to equip the British coking plants with their modern by-product recovery system on condition that they were to be at liberty to acquire the liquid residual—benzol. The suggestion found certain favour in British eyes. The benzol was a drug on the home market, so its shipment to Germany was regarded as the solution of a perplexing problem. In this manner Germany secured the necessary raw materials from the British scrap-heap to feed her dye industry and to pile up her reserves of high explosives against the day when the gauntlet should be thrown down. There is a tendency in certain quarters to assail the cunning competitor, but are we rather not to blame for our own extreme shortsightedness, lack of initiative, and indolence?
The coking-ovens, however, only absorb a portion of our total output of coal, the annual average of which may be set down at approximately 260,000,000 tons. Subtracting 60,000,000 tons as the export figure, we are left with a round 200,000,000 tons consumed at home. Of this figure a round 100,000,000 tons is consumed during the year in the domestic fire-grate.
We all revel in the blazing fire in our rooms during the winter, but do we reckon on the cost? The volume of heat thrown into the room is but a trifling proportion of that emitted by the glowing coal. The greater part flies up the chimney, together with all the benzol, ammonia, and other valuable constituents of the fuel. Immense volumes of soot pour forth from the chimneys to pollute the atmosphere, disfigure buildings and monuments, while the damage wrought within the rooms to fabrics, curtains and other embellishments runs into millions sterling during the year.
Could this waste be avoided? Certainly. The domestic fire-grate does not possess a single virtue. It should be scrapped forthwith. Coal, as a household fuel, should be prohibited. It should be carbonized. Coke, when burned under the most advantageous conditions, throws off as much, if not more heat, and can be induced to shed practically the whole thereof into the apartment. As the alternative to coke we might rely exclusively on gas, releasing the whole of the carbon residue, approximately 70 per cent. of which results from the distillation of every ton of coal for industry. If we presume an average of 10,000 cubic feet derivable from every ton of coal, then we find that the 100,000,000 tons burned annually in the household grates would give us 1,000,000,000,000—one billion—cubic feet of gas, the whole of which is at present being lost up the chimney. From this enormous volume of gas, each 10,000 cubic feet of which contains on the average two gallons of benzol capable of reclamation, we could, if we were sufficiently energetic and enterprising, obtain 200,000,000 gallons of benzol—twice the petrol imports for the year 1913. In comparison with what liquid fuel we could derive from our coal the actual 41,000,000 gallons secured to-day certainly appears to be trifling.
Our methods of burning coal in the home, which is appallingly wasteful, is equalled by the general folly investing our system of gas supply, which is equally improvident, simply because we prefer to cling to the obsolete order of things rather than to march with progress. Years ago, to protect gas-consumers, a standard of value was established. The gas had to comply with a certain candle-power standard. The unit thus was one of luminosity. Such a system was satisfactory in days gone by, when the practice was to use a burner and open flame of the fish-tail or bat’s-wing shape. Then some method of standardizing gas according to its luminous intensity undoubtedly was imperative.
But judgment of gas by its luminosity with an open burner is effete. It became relegated to the limbo of things that were by the discovery of Welsbach, which effected a complete and wonderful revolution in gas illumination. His invention supplied the means of securing brilliant illumination with heat. This may sound paradoxical, but is readily explained. The particles of the nitrates of the rare earths, thoria and ceria, which enter into the composition of the incandescent gas mantle, will not emit light until they have been raised to a high degree of incandescence. This can only be achieved by using the mantle in conjunction with an atmospheric, or Bunsen, burner.