For pt.I see ibid., vol.19, p.1273 (1986). Two samples of nominally identical material will usually charge each other if they are rubbed together asymmetrically, e.g. in such a way that a small region of one rubs across a large region of the other. It has previously been supposed that the asymmetric rubbing induced some physical difference, in particular a temperature difference, between surfaces, which in turn causes charge transfer. However, experiments on polymers (reported in the preceding paper) are not easily reconciled with this explanation. In this paper the authors show that it is not necessary to invoke any physical distinction between the two insulators to explain charge transfer. Certain electron distributions can result in net charge transfer during asymmetric rubbing even though the temperature (and other physical properties) remains exactly the same for the two surfaces. The authors present a quantitative model and they show that it is capable of explaining a wide range of experimental facts about charge transfer between identical insulators.