Rubber can erase pencil words, first discovered by British scientist priest in 1770. Before that, people rubbed pencils with bread. This discovery by priest caused a great stir because it brought great convenience to people. But the earliest eraser is made of natural rubber, wipe the word does not drop debris, just put the pencil end glued to the eraser, the more dirty. Later, people in the production of rubber added sulfur and oil and other substances, so that the eraser is easy to drop crumbs, erased pencil at the end with debris away from the eraser, so that the eraser can often keep clean, and will not get the paper dirty.