THE present position of the shale oil industry was clarified at an International Congress held in Glasgow in June last under the auspices of the Institution of Petroleum Technologists. Dr. E. F. Armstrong reports (J. Roy. Soc. Arts, August 12, 1938) that at the beginning of the Great War the yearly production of shale reached a maximum of 3¼ million tons; to-day only about half this quantity is produced. This is partly due to the fact that the oil yield is directly proportional to the fossil algae content of the shale, from which it is believed to originate; this fossil algae content is less in the lower and geologically older shale strata. Thus the average yield to-day is 16-20 gallons per ton, whereas, in 1875, it was 30 gallons per ton. Rapid development of natural petroleum has also influenced the shale industry. Shale has to be mined and distilled before oil can be obtained and, therefore, without some form of protection, shale oil cannot compete with petroleum oil. Nevertheless, in spite of obvious handicaps, the shale oil industry is being kept alive in Great Britain and other countries, and it may be that at some future date when natural resources of petroleum have been depleted it will become a major industry, particularly as it is capable of producing both Diesel oil and motor spirit.