Now oil has considerable advantages over coal. Its extraction is remarkably easy compared with that of coal. What is the boring of a well and the installation of some simple machinery on the surface compared with the expensive subterranean workings which are involved in the exploitation of a coal-mine? An oil-boring before the War cost a few hundred thousand francs, while the simplest workings for a colliery always necessitated an expenditure of several millions. The installations once made, oil flows by itself into the reservoirs, whence it is conducted by pipe-lines to the sea-ports and there pumped into the ships. It may be refined before exportation or only on arrival in the country where it is to be consumed. The expenditure upon labour in these various operations is extremely small, especially in undeveloped countries where native labour is employed. Thus, even at the present time, in the Dutch Indies the coolies are paid a florin a day. Now at the end of the War the employés of the _Royal Dutch_ in the Dutch Indies numbered only 1,000 Europeans and 2,906 natives and Chinese for a production of 1,706,675 tons. A native earned only 300 gold francs a year for 80 tons of oil extracted, refined and transported to the coast. After the Bolshevik revolution wages at Grosny were still only seven roubles a day, which, considering the depreciation of Russian money, represented very little. Generally the expenses of production in Russia did not exceed a few kopecks a pood (50 kopecks for one of the best-known firms, that of Akverdoff). Thus oil is bound to become in future more and more important as a fuel, because of its peculiarity in necessitating so insignificant a charge for labour--which protects it from the inconveniences resulting from the social crises in the midst of which we live--and because its net cost is so small. For half a century it was used only for lighting purposes, and then it had to compete with gas and electricity. At one time there was talk of limiting production! Between 1900 and 1910 the invention of the internal-combustion engine and the enormous development of motoring gave it new impetus. Fine oils only had been used up to then. Under pressure of the demand, it became customary to raise and refine poorer and poorer oils, giving from 60 to 75 per cent. of waste products. There remained the mazut[1] or fuel-oil, which required very high temperatures for combustion and which was very dirty in use.