Mass-to-charge ratio refers to the molecular or atomic mass number and "z" to the charge number of the ion; however, the quantity of "m"/"z" is dimensionless by definition. An ion of 100 atomic mass units ("m" = 100) carrying two charges ("z" = 2) will be observed at "m"/"z" = 50. In the 19th century, the mass-to-charge ratios of some ions were measured by electrochemical methods. In 1897, the mass-to-charge ratio of the electron was first measured by J. J. Thomson. By doing this, he showed that the electron was in fact a particle with a mass and a charge, and that
How to Dismantle an Atomic Bomb announced that if those tracks were leaked online, they would release the album immediately via the iTunes Store. Several months later, the finished album was leaked online, but the band did not release it earlier, despite previous comments. In late 2004, "Mercy", an unreleased track taken from the "How to Dismantle an Atomic Bomb" sessions, surfaced on the Internet through a fan who had been given a copy of the album containing the extra track. The track is of less than standard audio quality, but managed to become a favorite on fan websites. It was cut from the final release,