Tribo-electricity and friction. II.—Glass and solid elements
1. Experience teaches us that the arrangement of solids in a tribo-electric series is fallacious. We shall show in the next paper that in the case of three solids (A, B, C) A may be positive to B; and B to C; and yet C be positive to A. This may occur when the bodies are of different classes, say, metal, textile, glass, which have different physical and chemical characteristics. In the case of one material, one characteristic predominates; in another, another may be paramount. The true arrangement may prove ultimately to be in branching or parallel lines, rather than in one continuous line or series. The problem is to obtain reliable data of sign and amount of charge when two standard solids are rubbed together. The only hope of progress lies in the use of material of known composition and—even more important—of definite surface cleanliness and physical structure. Further, to obtain quantitative results the rubbing should be performed, not by hand, but in some regulated machine to insure consistency of action.