c13p18-both
We remember that in the case of the generation of heat through friction, as a result of an encroachment upon the cohesion of the material body involved, the relationship between levity and gravity in it changes from 'moist' to 'dry' and that the effect of this is the appearance of 'fire' and 'dust' as poles of a primary polarity. This process, however, is altered when the bodies subjected to friction are opposed to each other in the sense of a salt-sulphur polarity. The effect then is that the liberated levity, under the influence of the peculiar tension between the two bodies, remains bound in the realm of substance and becomes itself split up polarically.