When Silver Spencer used the glue on his bookmarks, how did it work? When was Saccharine discovered?

interventions changed the world but were made by mistake
When you think of people who have invented something that has changed the world, you immediately think of the achievements of some very intelligent scientist. But their success often comes in an unexpected way. Did you know that the medicine penicillin was discovered because of a mistake? It's amazing to think that something that was an accident then became something that the whole world now uses to stop serious illness.
Here are a few examples of inventions that were made by mistake:
Sticky notes
In 1968, scientist Spencer Silver created a type of glue that would stick to things but could be removed easily from any surface. He was really trying to create a super-strong glue but failed. Art Fry, another scientist, was tired of his bookmarks falling out of his books. He remembered Silver's special glue and wondered if this might be the answer to his problem. When he tried the glue on his bookmarks, they stuck and didn't damage the pages. lt worked. It was then that he thought of the idea of using the glue on notes.
Saccharine
Saccharine was discovered in 1879 by the chemist Constantine Fahlberg while he was working in his university laboratory. The discovery came because he forgot to wash his hands after spilling a chemical on them, and when he was eating his bread at lunch it tasted unusually sweet. lt was later produced in huge quantities as an artificial sweetener and is now used in soft drinks to reduce the sugar and calories.
Penicillin
Scientist Alexander Fleming invented penicillin, which helps stop infections by killing bacteria. He was on holiday and he had left a petri dish (a special dish used by scientists to grow bacteria) in his laboratory. When he returned, the dish had an unusual mould on it, but there were no bacteria growing. He realised that something in the mould was killing the bacteria. He also realised that if you use this substance on the human body, it stops serious illness. This became the first antibiotic, penicillin, which has saved millions of people's lives over the years.
Chocolate chip cookies
In the 1930s, Ruth Wakefield owned a very popular restaurant called the Toll House Inn in the United States. While making some chocolate cookies, she discovered she had no special baker's chocolate left and decided to use some normal chocolate instead. She poured it into the dough, but the chocolate did not mix with the dough and this was how the chocolate chip cookie was born.
As Mark Twain said: “Name the greatest of all inventors. Accident.” Many great inventions are the result of the creative use of a mistake.
 
1. When Silver Spencer used the glue on his bookmarks, how did it work?
2. When was Saccharine discovered?
3. What was the discovery of Alexander Fleming about the mould and bacteria?
4. How was the chocolate chip cookie born?