Purple Music is an unreleased song, recorded at some point in 1982 at Prince's Kiowa Trail Home Studio, Chanhassen MN, USA. It is unknown if it was considered for inclusion on 1999 or any other project.
The song is a somewhat monotonous uptempo track, sparsely instrumented by a bouncy drum machine beat provided by the Linn LM-1 and a synth bass line, a scratchy guitar lick reminiscent of Controversy and a simple synth-lead line, not too far removed from the lead line of All The Critics Love U In New York.
It has an anti-drug message in which Prince says that "purple music" does the same to his brain as reefer or cocaine. Prince's voice sounds slightly manipulated (although not to the effect that he would later utilize for the Camille songs), to suggest he is indeed getting high on his music as he sings.
The song made its first and live appearance 28 years after its recording, on 23 July 2010 (a.m.), played in a medley with All The Critics Love U In New York.
When Prince started playing it regularly on the Piano & A Microphone Tour in 2016 the song was listed on setlists as Welcome 2 The Freedom Galaxy. It is possible Prince worked on an updated studio version in 2016