Pumped into the column from storage tanks
The crude oil boils, rising as a vapor
Through the chambers of the refining tower:

Straight and branched, some linked in rings,
Paraffins, olefins, naphthenes, aromatics,
The fuel compounds separate when cooled,

The longer, heavier molecules condensing
As the shorter, lighter molecules rise
As vapors through the holes in the ceiling,

A fractional migration, almost expository,
The process a sustained equilibrium
Of ascending vapor and descending liquid,

With the heaviest fractions, the thick fuel oils,
The asphalt residuals, the bitumens,
The tars and waxes, sinking to the bottom,

And the excess gases of the fractionation,
The methane, ethane, propane, butane,
Vented from the stack and burned in flares.

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This poem is a distillation column. The refining process it describes, which employs a so-called "bubble tower" to separate the fractions of petroleum, first appeared in the oil industry in 1917, with a patent filed by Frank R. Lewis and Thomas S. Cooke of the Standard Oil Company (Indiana).