This invention rendered it no longer necessary for the gas to carry the constituents which contributed to luminosity, among which was benzol. With the mantle they are superfluous: in fact are deleterious. What is required is a gas rich in the constituents contributing to heat. Coal-gas, or as it is more familiarly called, town-gas, is rich in these two essentials. They are hydrogen and methane or marsh-gas. When burned under suitable conditions they are capable of giving off intense heat, and the higher the degree of incandescence to which the rare earths entering into the composition of the mantle can be raised, the more brilliant the illumination.

Consequently the time has arrived when the standardization of gas according to luminous power should be thrown overboard in favour of one based upon calorific value. This was introduced to a certain degree as a temporary expedient during the war, but it should now be made rigid. Signs of awakening to the true state of affairs are apparent. The research committee appointed to investigate this question has recommended that gas should be sold according to its calorific value, and that all gas-consuming appliances should be adapted to the new order of things.

Should legislation be passed endorsing these recommendations it will be possible for further huge quantities of benzol to be recovered from our coal, or rather the gas derived from the volume of coal annually absorbed for gas production. It is the benzol and toluene which impart the luminous intensity to the gas, but which are unnecessary for the production of heat. At the present moment the quantity of benzol reclaimed from the coal absorbed by the gas-works is approximately 21,000,000 gallons a year—a fraction of what it might be.

We may safely assume that of the 270,000,000 tons of coal we draw from our collieries every year, at least 160,000,000 tons are capable of such treatment as will enable the volatile liquid fuel to be recovered. Upon the basis of two gallons per ton of coal this would represent 320,000,000 gallons of benzol, of which huge quantity all but 41,000,000 gallons are being lost under contemporary conditions. The value of this spirit at the moment may be set down at approximately 2s.—50 cents—per gallon. Thus we are deliberately throwing away £27,900,000—$139,500,000—a year. It is being permitted to vanish into thin air. This figure serves to bring home what the losses arising from the neglect of waste really represent, and also reveals our extraordinary lack of imagination and enterprise.

Were we to recover the whole of the benzol content of coal we should not only be able to satisfy the whole of the needs, aggregating about 150,000,000 gallons a year, of the domestic motor industry, but we should be able to meet the requirements of the other industries to which benzol is indispensable. There would be no need to grow apprehensive concerning our coal-tar dye industry and the manufacture of other products dependent upon materials derived from coal. The British dye industry is in its infancy. At the moment its benzol requirements are modest, being approximately 4,000,000 gallons a year. But it is an industry which, given full opportunity, promises to thrive and to expand amazingly, and so one may safely anticipate that its benzol needs will advance by leaps and bounds.

Moreover, one must not forget that, as yet, benzol itself is but little understood, because it has not received the attention it deserves from the chemist. If we decide to exploit our coal to the extent which prudence dictates, the wizards of the laboratory will be encouraged to embark upon further original research, and it is quite possible that they will reveal other and equally promising applications for the spirit of coal.

While domestic users have not been fully alive to the possibilities of British benzol other countries, notably France, were eager buyers of what we ourselves failed to appreciate. We need not sacrifice this export trade: rather we should be able to cultivate and to expand it to a very pronounced degree.

In view of the part which benzol played in the war one hopes that the Government will consider the situation in a more enlightened spirit. The circumstance that we might be able to retrieve a round £28,000,000—$140,000,000—a year should offer every inducement towards compulsory modernization of methods in this particular province. Benzol should be made a national issue. To compel the use of coke, instead of coal, in the household, would go a long way to relieve the coking-ovens and other distillation plants of all apprehensions of glut accumulations of coke, and would tend to steady the output of this fuel, as well as to bring about the abolition of the wickedly wasteful bee-hive oven. Our gas standardization system should be overhauled to ensure the sale of gas by its calorific rather than its luminous value. The country might even do worse than to nationalize benzol, taking over the whole of the output as a corollary to the compulsory distillation of all bituminous coal. As the alternative it might undertake to purchase what the trade could not sell, for naval purposes, inasmuch as in the Senior Service the consumption of petroleum oils has reached an impressive figure from the increasing use of oil fuel, practically the whole of which at present has to be imported.

CHAPTER XVII
FERTILIZERS FROM WASTES

Nourishment is as essential to the land as it is to the animal kingdom. This is particularly so in countries, such as the British Isles, where the land has been worked assiduously, year after year, for centuries. The co-relation between fertilizers and crop yields is too obvious to demand other than mere mention. The main problem, in such circumstances, is to secure sufficient quantities of the nutritive constituents necessary, and at a price which shall render their utilization profitable to the farmer, and enable the resultant food products to be brought within the reach of the public at an attractive figure.