Static electricity

It was discovered centuries ago that certain types of materials would mysteriuosly attract one another after being rubbed together. For example, after rubbing a piece if silk against a piece of glass, the silk an glass would tend to stick together. Indeed, there was an attractive force that could be demonstrated even when the two materials we seperated. Glass and silk aren't the only materils known to behave like this. Anyone who has ever brushed up agaist a latex baloon only to find that it tries to stick to then has experienced this same phenomenon. Paraffin wax and wool cloth are another pair of materials early experimenters recognized as manifesting attractive forces after eing rubed together. This phenomenon became even more interesting when it was discovered that identical materials, after having been rubbed with their respective cloths, always repelled each other. It was also noted that when a piece of glass rubbed with silk was exposed to a piece of wax rubbed with wool, the two materials would attract to one another. Furthermore, it was found that any material demonstrating properties of attraction or repulsion after being rubbed could be classed into one of two distinct categories:attracted to glass and repelled by wax, or repelled by glass and attracted to wax. It was either one or the other, there were no materials found that would be attracted to or repelled by both glss and wax, or that ractd to one without reacting to the other.