The crude oil content of the shales is surprisingly great, for these shales yield approximately 60 gallons of oil per ton, or considerably more than double as much as the Midlothian shales. Dr. Forbes Leslie asserts that there is already proved over 2,000,000,000 tons of shale on the properties in Norfolk, and after having carefully inspected the whole of the fields on many occasions, I think Dr. Leslie’s statement may be taken as very conservative, for after all it is only a question of a simple sum of calculation which allows one to arrive at the figures above quoted. Commercial developments have already been commenced on the Norfolk fields, and it is safe to assume that they will become of enormous National importance, since the production of home oil supplies is to-day considered of vast National interest. The other shales--such as the Kimmeridge shales of Dorset and Sussex--are not being worked commercially in spite of strenuous efforts, and there remains much to be done before a steady supply of petroleum can be counted upon from these sources. Of the other possible sources of supply, coal yields too little, and at the same time is considered too valuable to be utilized on a general scale; lignites are not yet opened for development on a sufficient scale; and peat has proved troublesome and expensive to treat owing to the difficulty of eliminating the water. This, therefore, leaves cannel coals, torbanites, and blackband ironstones, which are closely associated and, in numerous cases, easily obtainable. Cannel coal, I should explain, differs from the ordinarily known coal on account of its being less carbonized; it contains many fragments and particles of vegetable matter still showing their natural forms, though flattened by pressure. The percentage of hydrogen to carbon is higher in a cannel coal than in the bituminous coal, the percentage of inorganic matter is usually higher also, and the fracture and general appearance serve to distinguish this variety of carbonaceous deposit. CHAPTER X PETROLEUM IN THE BRITISH EMPIRE The desire that the British Empire should be self-supporting in every possible way has been the predominating idea of our statesmen for many years: it is to be regretted, however, that such little progress has been recorded in the direction of the achievement of a practical result. This remark applies to many commodities, yet to none more so than to petroleum and its products. To-day, as much as at any preceding time, the Empire is dependent upon foreign sources of supply for the vast bulk of its petroleum products. It is true that in the United Kingdom there is a growing production of oil from the shale-fields of Scotland, but this total represents but a fraction of the large quantities of products which are annually required to meet the ever-increasing demands in commercial and domestic circles.