“The volume of gasoline sales peaked in 2007,” Lenard notes.
For convenience these rays outside the tube have since been known as "Lenard rays."
In air at atmospheric pressure the Lenard rays spread out very diffusely.
He was following up the work of Lenard, and he one day covered a "Crookes tube" with some black stuff.
Lenard found that when pure water falls upon water the neighbouring air takes a negative charge.