Here are some of the most notable examples.
What important scientific discoveries were an accident?
So, without further ado, here are some scientific discoveries that were a complete accident. This list is far from exhaustive and is in no particular order.
1. Quinine was discovered by complete accident (apparently)
Originally found in the bark of the cinchona tree, the discovery of this important anti-malarial compound was a pure accident.
While it was being used by Jesuit missionaries in South America to treat malaria since 1600, they were taught about the substance by native Andean peoples in the first place.
According to their legends, the first discoverer was a feverish Andean man who was lost in the jungle. Suffering from malaria, he drank from a pool of water at the base of a cinchona tree.
Although bitter to the taste, his fever lifted and he survived to pass on what he had learned.
2. X-rays were also discovered by accident
While working on a cathode ray tube, German physicist Wilhelm Roentgen noticed something strange was happening. Despite the tube being covered, he saw a nearby fluorescent screen glow when the tube was on and the room was darkened.
He tried to block the apparently invisible rays but most things didn't have any effect. When he tried using his hand he noticed that he could see his bones in an image projected on the screen.
Amazed, he replaced the screen with a photographic plate and the first x-ray ever was created.
3. The microwave was also a complete fluke
Back in the 1940s, Percy Spencer was working on a radar-related project. While testing a new vacuum tube, he noticed that a chocolate bar in his pocket had melted more rapidly than expected.
Intrigued, he starting aiming the tube at other objects like eggs and popcorn kernels to see what would happen. After they too became heated, he concluded that microwave energy could have a new interesting application.
Microwave ovens soon followed.
4. "Velcro" was another accidental discovery
Also back in the 1940s, a Swiss engineer called George de Mestral, made an interesting discovery while walking his dog. When they returned home he decided to examine the burdock seeds that had stuck to his clothes.
He noticed they had lots of tiny hooks that easily attached and stuck firmly to fabric and fur. de Mestral realized he could create a new fastening system using the concept, and "Velcro" was brought into existence.
5. The discovery of radioactivity was another by accident
Henri Becquerel, while enamored with x-rays back in the late 1890s, he decided to figure out their connection with phosphorescence. After trying to expose photographic plates using uranium salts, he was hoping to absorb "x-ray energy" from the Sun.
After thinking he needed sunlight for the experiment to work, the sky was overcast and he abandoned it for the day. But when he developed the previously unexposed plates he noticed that they had some fogging.
It was clear to Becquerel that the uranium salts must be the culprit and were emitting some kind of strange rays. The phenomenon of radioactivity had been discovered.
6. Sweet'N Low was found by accident
Sweet'N Low, or saccharin, was discovered by chance in 1878 by Constantine Faglberg. He was analyzing coal tar at the time.
After forgetting to wash his hands one day, and picking up a roll to eat, he noticed that it tasted unusually sweet. He later started tasting (as you do) some of the other compounds he'd created and found that one combining o-sulfobenzoic acid with phosphorus chloride and ammonia was the culprit.
He filed for a patent in 1884.
7. LSD was also found by accident
Back in the late-1930s, a scientist called Albert Hofmann was studying a chemical called Lysergic acid. While working with it, he accidentally tasted it and felt restless and dizzy.
At home, he had some "interesting" dreams and decided to experiment with dosages when he returned to the lab on the 19th of April, 1943 -- what is with scientists and tasting random chemicals?
This was the first planned experiment with LSD -- and it wouldn't be the last.
8. Penicillin was another accidental discovery
Sir Alexander Fleming, in 1928, noticed that mold had started to grow in a petri dish of one Staphylococcus bacteria cultures. While trying to salvage cultures unaffected by the mold, he noticed that bacterial colonies would not grow near the mold.
Fleming soon realized that the mold must be releasing some kind of substance that inhibited bacterial growth. Penicillin was later introduced in the 1940s, saving countless lives since.
9. Insulin was also a freaky discovery
Back in the late-1880s, two doctors were attempting to uncover the pancreas' role with digestion. After removing one from a test dog, they noticed that flies were gathering around the dog's urine.
After testing the urine, they noted that it had a high sugar content.
They realized they had inadvertently given the dog diabetes.
A little later, further experiments during the 1920s built on their work and were able to isolate the pancreatic secretion known as insulin.
10. Vulcanized rubber was also an unintentional discovery
Charles Goodyear spent many years trying to turn rubber into something that wouldn't freeze when it's cold or melt when it's hot. After trying many things, he eventually tried using some sulfur.
In frustration, he tossed it into the air, as the story goes, and it landed on a stove. But instead of melting it charred creating a leathery, heat-resistant and waterproof substance.
Vulcanized rubber was born.
11. Teflon was also a fluke
Roy Plunkett was working in the Dupont Company's Jackson Laboratory in 1938 when he started researching new refrigerants. One such substance he experimented with was tetrafluoroethylene (TFE) gas.
After returning to an open cylinder he'd stored some of the gas in, he discovered a strange white powder on the inside. Curiosity compelled him to conduct some tests on it, and he found that it was heat resistant, had low surface friction and was inert to corrosive acids.
It was, effectively, an ideal substance for cookware.
12. Vaseline was also an accident
Back in the late-1850s, one chemist Robert Chesebrough was investigating an oil well in Pennsylvania. He caught upon a rumor of some strange substance called "rod wax" that intermittently gunked up some of their machinery.
He also heard that workers at the well had been using it to soothe cuts and burns on their skin and took some home to conduct tests.
Vaseline, or petroleum jelly, was soon a thing.
13. Shatterproof glass was also discovered by accident
Shatterproof glass, like the kind used in your car's windshield, was also an accidental discovery. When Edouard Benedictus, a French scientist was experimenting with cellulose nitrate in 1903, he accidentally dropped the flask it was contained in.
The flask broke but didn't shatter. Not only that, but the flask, though broken, maintained its shape.
Benedictus postulated that the plastic coating had somehow helped maintain the glass' shape. Safety glass had been discovered.
14. The dinosaur, Deinonychus, that inspired Jurassic Park's version of the Velociraptor was an unintended discovery
While Velociraptors are indeed a real dinosaur, their size and stature in the Jurassic Park franchise certainly are not. They are more akin to Velociraptor's big cousin Deinonychus.
Deinonychus, meaning "terrible claw," was found by complete accident in the 1930s. While searching for a completely different dinosaur, Tenontosaurus, Barnum Brown stumbled across the remains of this iconic carnivorous dinosaur.
15. The first evidence of the "Big Bang" was also an accidental discovery
Astronomers Arno Penzias and Robert Wilson noticed some strange yet annoying "noise" from their large antenna while observing the space between galaxies. The pair also noticed that the odd buzzing sound appeared to be everywhere they pointed their apparatus.
What they had inadvertently stumbled upon was the cosmic microwave background -- the leftover radiation from the "Big Bang."
They shared the 1978 Nobel Prize for their discovery.