Ionisation features the expansion and variation of
rhythmic
cells, and the title refers to the
ionization of
molecules. As the composer later described, "I was not influenced by composers as much as by natural objects and physical phenomena". Varèse also acknowledged the influence of the Italian Futurist artists
Luigi Russolo and
Filippo Tommaso Marinetti in the composition of this work. Both
Chou Wen-chung and Jean-Charles François have analyzed the structure and
timbre features of
Ionisation in detail. András Wilheim has noted that only the last 17 measures of
Ionisation include musical tones of the "traditional tonal system", where any five successive chords contain the 12 tones of the
chromatic scale. Holder writes, "The reconceptualization of pitch was one of Varèse's great insights. He was able to reinvent the role of concert percussion in a radical and refreshing manner, primarily by establishing pitch relationships between instruments of individually indeterminate pitch... its performance is a reenactment of a great rite of passage for what was then a fresh and previously unrecognized musical ensemble."
Jack Skurnick, director of
EMS Recordings, produced early post-war recordings of Varèse; this piece appears on the first Varèse LP, EMS 401: Complete Works of Edgar Varèse, Volume 1.
Ionisation had also been the first work by Varèse to be recorded in the 1930s, conducted by
Nicolas Slonimsky and issued on 78 rpm Columbia 4095M. The players for the recording included, in addition to the composer himself on the sirens,
Carlos Salzedo on Chinese blocks,
Paul Creston on anvils,
Wallingford Riegger on guiro,
Henry Cowell on piano, and
William Schuman on the lion's roar.
Sidney Finkelstein wrote in the EMS LP liner notes about the work: == Instrumentation ==