284 Science and Human Welfare
the acid-treating or dewaxing plant, or in the treatment of
the boiler or cooling water.
Some years ago it was thought that the ultimate in motor
fuel would be reached by the creation of a gasoline equivalent
in power and anti-knock qualities to those of pure iso-octane.
So superior was iso-octane in these respects that it was
arbitrarily given the octane rating of ɪoo, which became the
standard in evaluating all gasolines. Extraordinary strides
have been made in the fabrication of airplane engines, pro-
pellers, and bodies. The advances in design and construction
of the engines have been made possible, to a large degree, by
the oil industry in producing the ɪoo-, and higher, octane
gasoline and all the necessary lubricants. Increased manifold
pressure increases explosion pressure and requires a higher
octane fuel in order to avoid detonation. The use of super-
chargers, with high-octane fuel, increases the speed, cruising
ranges, and ceilings of the planes. The use of ιoo-octane
aviation fuel will give our aircraft a definite advantage over
aircraft of our enemies and may, in effect, be one of the de-
ciding factors of the war. The octane ratings of aviation
gasoline which has been collected from captured and shot-
down German planes average around 87. It has been reported
that the German invasion of England in 1940 was stopped by
the R.A.F. because the English fighting planes were powered
with ιoo-octane fuel.
Tetraethyllead, the product of Midgley’s researches, broke
down one of the barriers that was blocking the road to auto-
motive progress—the barrier of “knock.” Added to gasoline
it increased the power and performance of many million
automobiles. Although tetraethyllead has played an ex-
tremely important part in increasing the efficiency of gaso-
line engines, it will probably lose its importance due to the
high-octane gasolines which chemical technology is rapidly
providing.