The electrical and spatial characteristics of a volume electrical discharge are studied as functions of the ratio of partial pressures of the mixture components at varying initial voltage. Early in the discharge, hot (plasma) cathode spots are observed with diffusive plasma flares developing above them. Overlapping of the flares produces a volume plasma column. The column homogeneity depends on the diffusive-flare density, and the length of the volume-discharge stage is determined by the time it takes for one or more flares to transform and give rise to the channel stage. Estimates of the ionization, attachment, and ion recombination rates are used to show that the electron density in plasma channels is two orders of magnitude lower than that of positive and negative ions forming a stagnant stiff skeleton of the plasma.