Chemistry in the Industries 285
•Military airplanes in 1928 used gasoline of about 60 octane
rating. In 1931 the standard Army aviation gasoline was
87-octane and airplane engines were developed to utilize this
quality fuel which gave a 33 per cent increase in power per
unit weight compared to 60-octane gasoline. Engines, de-
signed for using loo-octane gasoline, yield 15 to 30 per cent
greater output while take-off distance is reduced 20 per cent
and climbing speed increases 40 per cent. Leadership in
aviation octane gasoline rests in the United States. Mr.
Bruce K. Brown, Assistant Deputy Coordinator for War,
said in September: “It has become quite evident that the
needs of the United Nations for ιoo-octane gasoline will
eventually exceed the productive capacity of all aviation
gasoline plants now built, building, or authorized.” Such
reasoning undoubtedly led to the curtailment of the syn-
thetic rubber program.
Cracking, in the petroleum industry, may be defined as
the breaking down of the hydrocarbon molecules into
smaller ones with attendant polymerization and other side
reactions. When cracking by heat was first recognized, its
only commercial significance was as a possibility for produc-
ing more kerosene from crude oil. The process was stimulated
by the advent of the automobile and the airplane. Cracking,
in the beginning, was a thermal reaction taking place in
liquid phase. The stills became a combination of pipe still,
pressure reaction chamber, and fractionating tower. The
Burton, Cross, Dubbs, Holmes-Manley, tube and tank, and
other processes were modifications differing in engineering
design. The science of cracking is distinctly an American de-
velopment and its commercial application an American
achievement.
Later research showed that high temperature favored the
production of better octane fuels. Cracking was developed