Gluesticks

What products, today, were the result of a mistake to create a different product?

I've heard that 3M's Post-It Notes were the result of a mistake to create a new super glue. And that Kellogg's Corn Flakes were invented when the Kellogg brothers mistakely left their kettle cook too long when trying to create a different food product. And that the Chinese were trying to develop a health product that would result in immortality -- which failed -- but is being used today as gunpowder. Do you know of other products that were created as a by-product of mistakenly trying to create something else?

Public Comments

1. Super glue was used on the battlefield as a sort of instant stitches. Many medicines were created for a purpose other than intended.
2. Potato chips were an accident when some thin potato slices fell into a deep fryer.
3. margerine? when they were trying to make plastic, they were one molecule off, and ended up with margerine. not sure if it really happened this way, but it is a fact that margerine is one molecule away from being plastic. flies won't even eat it. : )
4. The original penicillin was discovered by accident. I can't recall what the circumstances were, but know that it was almost not noticed that the new stuff had obliterated some bacteria.