Songfacts®:

• Like his "Strange Kind Of Woman," the girl in "Fireball" has lead singer Ian Gillan in a tizzy; she's a magic woman wreckin' is soul. She might not even be from this planet, but he knows he loves her.
• This song opens with a the sound of a fireball hurtling through space, kicking off the album with a futuristic fury. That's what they were going for at least. But the sound itself is simply a recording of an air conditioner being turned on.
  
  This improvised sound effect was the work of a young studio assistant named Mike Thorne, who was helping engineer Martin Birch on this track. One of the group turned to Martin and suggested the sound of a machine starting up would be a great way to get the song going. Martin could not think of anything suitable off the top of his head, but Thorne suggested the sound of an air conditioning unit turned on could do the trick. He duly recorded it and the band told people who asked what the sound was that it was made by a "special" synthesizer.
• At right about this point in Deep Purple's career, Ritchie Blackmore was hospitalized with a case of mononucleosis. Their agent, sweating bullets at the million dollar tour he had booked for them, called another client of his in a panic. That client was Al Kooper (The Blues Project, Blood Sweat & Tears), himself just recovering from hospitalization with food poisoning. The agent dispatched Kooper to fill in for Blackmore. Kooper, more of a keyboardist than a guitarist, was dumbfounded that anyone would ask this of him, but gamely complied on the condition that it was just to humor the Deep Purple members until a better replacement was found. According to Kooper's book Backstage Passes and Backstabbing Bastards, Kooper actually showed up to audition with Deep Purple who seemed more than happy to work around his deficiencies in a pinch, but in the end Kooper backed out and recommended guitarist Randy California (of Spirit) to fill in. Randy California agreed to the gig, but eventually on the first tour stop in Hawaii barricaded himself in his hotel room and refused to play, and alas, the tour was canceled.