<P> By 1910 increased automobile production and the resultant increased gasoline consumption combined with the growing electrification of lighting producing a drop in kerosene demand created a supply problem . It appeared that the oil industry would be trapped into over producing kerosene and under producing gasoline since simple distillation could not alter the ratio of the two products from any given crude . The solution appeared in 1911 when the Burton process created thermal cracking of crude oils which increased the percent yield of gasoline from the heavier hydrocarbons and this was combined with expansion of foreign markets for the export of surplus kerosene which the domestic market no longer needed . These new thermally "cracked" gasolines were believed to have no harmful effects and would be added to straight run gasolines . There also was the practice of mixing heavy and light distillates to achieve a desired Baumé reading and collectively these were called "blended" gasolines . Gradually volatility gained favor over the Baumé test though both would be used in combination to specify a gasoline . As late as June, 1917 Standard Oil (the largest refiner of crude oil in the United States at this time) would state that the most important property of a gasoline was its volatility . It is estimated that the rating equivalent of these straight run gasolines varied from 40 to 60 octane and that the "High - Test" (sometimes referred to as "fighting grade") probably averaged 50 to 65 octane . </P> <P> Prior to the American entry into World War I the European Allies were using fuels derived from crude oils from Borneo, Java and Sumatra which gave satisfactory performance in their military aircraft . With the United States entry in April, 1917, the U.S. became the principal supplier of aviation gasoline to the Allies and a decrease in engine performance was noted . Soon it was realized that motor vehicle fuels were unsatisfactory for aviation and after the loss of a number of combat aircraft attention turned to the quality of the gasolines being used . Later flight tests conducted in 1937 showed that an octane reduction of 13 points (from 100 down to 87 octane) decreased engine performance by 20% and take - off distance was increased 45 percent . If abnormal combustion were to occur the engine could lose enough power to make getting airborne impossible and a take - off roll became a threat to the pilot and aircraft . On August 2, 1917, the Bureau of Mines arranged to study fuels for aircraft in cooperation with the Aviation Section of the Signal Corps and a general survey concluded that no reliable data existed for the proper fuels for aircraft . As a result, flight tests began at Langley, McCook and Wright fields to determine how different gasolines performed under different conditions . These tests showed that in certain aircraft, motor vehicle gasolines performed as well as "High - Test" but in other types resulted in hot - running engines . Also, gasolines from aromatic and naphthenic base crude oils from California, South Texas and Venezuela resulted in smooth running engines . These tests resulted in the first government specifications for motor gasolines (aviation gasolines used the same specifications as motor gasolines) in late 1917 . </P> <P> Engine designers knew that according to the Otto cycle power and efficiency increased with compression ratio but experience with these early gasolines during WW I showed that higher compression ratios increased the risk of abnormal combustion producing lower power, lower efficiency, hot running engines, and could lead to severe engine damage . To compensate for these poor fuels early engines used low compression ratios and this required relatively large, heavy engines to produce limited power and efficiency . The Wright Brothers first engine used a compression ratio as low as 4.7 to one and developed only 12 horsepower from 201 cubic inches and weighed 180 pounds. . This was a major concern for aircraft designers and the needs of the aviation industry led the search for fuels that could be used in higher compression engines . </P> <P> Between 1917 and 1919 the amount of thermally cracked gasoline utilized almost doubled . Also, the use of Natural gasoline increased greatly . During this period many states established specifications for motor gasoline but none of these agreed and were unsatisfactory from one standpoint or another . Larger oil refiners began to specify unsaturated material percentage (thermally cracked products caused gummming in both use and storage . See Saturated and unsaturated compounds and unsaturated hydrocarbons are more reactive and tend to combine with impurities leading to gumming). In 1922 the government published the first specifications for aviation gasolines (two grades were designated as "Fighting" and "Domestic" and were governed by boiling points, color, sulphur content and a gum formation test) along with one "Motor" grade for automobiles . The gum test essentially eliminated thermally cracked gasoline from aviation and thus aviation gasolines reverted back to fractionating straight - run naphthas or blending straight - run and highly treated thermally cracked naphthas . This situation persisted until 1929 . </P>

Which type of energy is contained in a tank of gasoline