How was the pencil with an eraser invented? Come on, everybody, 3Q.

In 1770, British scientist joseph priestley said, "I saw a substance that is very suitable for erasing pencil handwriting. At that time, the whole of Europe used rubber particles cut into small squares to erase handwriting. This substance is called an eraser. Edward Gnehm, another British engineer, is believed to have invented the eraser in 1770. Before that, people used bread crumbs to erase handwriting. Naimei said that once he accidentally picked up a rubber as bread crumbs, but found that the effect was very good, so he began to produce and sell rubber. The original eraser was inconvenient, because the unprocessed eraser was easy to rot. It was not until 1839 that the inventor Charles Goodyear discovered that vulcanization could improve the quality of rubber, and the eraser became reliable. 1858, a man in Philadelphia, USA, obtained a patent for embedding an eraser at the end of a pencil. However, the patent of this pencil with eraser was later revoked because it was judged as "just embedding two existing things together, not a new product". The English name of eraser is in Britain and Australia, and eraser is called eraser. ; But in America, rubber is one of the common names of condoms, and the name of eraser is eraser. This difference is often regarded as a joke by Americans. Now there are many kinds of erasers to meet different needs. Some pencils have a small eraser at the end. Most of these erasers are pink and the surface is smooth gum. They perform well on most occasions, but sometimes they get stuck on paper. If you push too hard, the eraser still has a chance to break the paper. When erasing handwriting, the eraser will leave a residue on the paper. If it is not cleaned properly, these residues will leave marks on the paper. Another kind of eraser is a brown eraser commonly used by artists, which is made of soft and rough rubber. Its design is easy to erase large areas of traces without damaging the paper. But this eraser can't erase handwriting effectively and accurately. Another eraser commonly used by artists is called soft eraser. It is mainly made of a gray material and rubber with gum. Its strength makes it leave no residue, so its life is longer than other erasers. It eliminates handwriting by "absorbing" graphite. This eraser can not only erase the handwriting (in fact, it can accurately remove the handwriting), but also be used to highlight important parts or make the work more detailed. But it is not good at removing large areas of handwriting, and it will get dirty or even stick to paper if it is overheated. Soft polyethylene-based eraser has the texture of plastic, and its function is the same as that of ordinary pink eraser. These erasers are softer than pink erasers, so they are unlikely to damage the paper. Polyethylene rubber is generally white.