  We report here direct measurements of the destruction of charge quantization
in a single electron box, the first over the full range of box-to-lead
conductance values from G ~ 0 to the conductance quantum G_q = 2e^2/h, using a
sensitive single-electron transistor (SET) electrometer. The sensitivity of the
electrometer is measured to be dq ~ 6 x 10^-5 e/sqrt{Hz} and its superiority to
conductance measurements of charge fluctuations is clearly demonstrated. As the
rate of quantum mechanical tunneling from the box to its lead is increased, the
quantization of charge is destroyed, disappearing entirely at G = G_q in
agreement with theory.
