Discovering Oxygen: A Brief History

Because there are three different dead guys who regularly vie for credit for discovering oxygen, we’ve staged a little friendly competition to establish which of these great men deserves the title of the O-master. In evaluating the contenders, we’ll look at when they isolated oxygen and how their experiments furthered our understanding of the element. In addition to bragging rights, the winner takes home one zillion liters of oxygen.

Contender 1: Carl Wilhelm Scheele

Nationality: Swedish
Occupation: Apothecary

Biggest Accomplishment: In 1772, he was the first person to figure out a way – actually a couple of ways - to isolate oxygen. He discovered that mercuric oxide, silver carbonate, magnesium nitrate, and potassium nitrate all gave off the same gas when heated. Scheele dubbed the mystery element “fire air” because he noticed that it produced sparks when it came into contact with charcoal dust.

Other Biggest Accomplishment: Discovered chlorine

Biggest Shortcoming:

Bad timing. Scheele didn’t publish his discovery until 1777, in a treatise called Chemical Observations and Experiments on Air and Fire. By that time, Joseph Priestley had already written a paper describing his findings and published the comprehensive Experiments and Observations on Air. Lavoisier had also successfully isolated the gas. Because Scheele waited so long to get the word out, his groundbreaking experiment was often overlooked by other scientists, earning him the nickname “Hard Luck Scheele.”

Contender 2: Joseph Priestley

Nationality: British

Occupation: Radical Unitarian Minister

Biggest accomplishment: In 1771, Priestley noticed that a mouse in a sealed jar would eventually collapse. He then tried slipping a sprig of mint inside and realized the plant magically revived his subject. Realizing that plants did something to freshen up the air, he wrote to his friend Benjamin Franklin, saying he hoped his discovery would stop people from cutting down so many trees.

Priestley didn’t actually isolate this mystery gas until August 1, 1774, when he heated some mercuric oxide powder and discovered that it gave off a gas that could reignite a glowing ember. He collected large amounts of the gas and tried breathing it himself. After a few puffs, Priestley was hooked. He declared, “My breast felt peculiarly light and easy for some time afterward.”

Other Biggest Accomplishment: Invented seltzer water

Biggest Shortcoming: Priestley just wouldn’t let go of phlogiston theory – a crackpot hypothesis that argued combustion was fueled by an invisible substance called phlogiston. Priestley believed that his mystery gas supported combustion because it was pure and could absorb phlogiston released by burning substances. That’s why he was pushing to name oxygen “dephlogisticated air.”

Contender 3: Antoine Laurent Lavoisier

Nationality: French

Occupation: Tax farmer/Commissioner of the Royal Gunpowder and Saltpeter Administration

Biggest Accomplishment: Lavoisier debunked phlogiston theory. Up until then, scientists couldn’t explain why tin gained weight when it was burned; if it was releasing phlogiston, it should lose weight. Lavoisier realized that there was no way phlogiston could have a negative mass and set out to prove that combustion was caused by something else. He heated Mercury until calx formed, then he heated the calx until it gave off a clear gas. Lavoisier realized combustion resulted from a chemical reaction with this gas – not some flammable mystery element called phlogiston. He dubbed the gas “oxygen” – a name that referred to its ability to create acids.

Other Biggest Accomplishment: Helped establish this thing called the metric system, which some people supposedly use.

Biggest Shortcoming: Lavoisier might have been the one to name oxygen, and for that, we’re grateful (nobody would be caught dead in a dephlogisticated air bar). However, he was not the first to isolate the gas or recognize its unique properties. His methods weren’t even original. In fact, Lavoisier had been in contact with both Priestley and Scheele and borrowed from their experiments.

And the O-Master Is...

We’re giving this one to Joseph Priestley. Although he gets points for publishing first, his real breakthrough was his realization that plants gave off oxygen. This discovery enabled future scientists to understand cellular respiration and photosynthesis – both of which are absolutely essential to life on Earth. We’re also giving Priestley points for recognizing the commercial potential of oxygen when he anticipated that the pure air could be a hit at parties. Sure enough, over 200 years later, oxygen bars have become a thing!

So next time you take a breath (hopefully soon), think of Joseph Priestley and his iconic experiment, which took place exactly 238 years ago today.

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'Lime Disease' Could Give You a Nasty Rash This Summer
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A cold Corona or virgin margarita is best enjoyed by the pool, but watch where you’re squeezing those limes. As Slate illustrates in a new video, there’s a lesser-known “lime disease,” and it can give you a nasty skin rash if you’re not careful.

When lime juice comes into contact with your skin and is then exposed to UV rays, it can cause a chemical reaction that results in phytophotodermatitis. It looks a little like a poison ivy reaction or sun poisoning, and some of the symptoms include redness, blistering, and inflammation. It’s the same reaction caused by a corrosive sap on the giant hogweed, an invasive weed that’s spreading throughout the U.S.

"Lime disease" may sound random, but it’s a lot more common than you might think. Dermatologist Barry D. Goldman tells Slate he sees cases of the skin condition almost daily in the summer. Some people have even reported receiving second-degree burns as a result of the citric acid from lime juice. According to the Mayo Clinic, the chemical that causes phytophotodermatitis can also be found in wild parsnip, wild dill, wild parsley, buttercups, and other citrus fruits.

To play it safe, keep your limes confined to the great indoors or wash your hands with soap after handling the fruit. You can learn more about phytophotodermatitis by checking out Slate’s video below.

[h/t Slate]

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Why Eating From a Smaller Plate Might Not Be an Effective Dieting Trick 
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It might be time to rewrite the diet books. Israeli psychologists have cast doubt on the widespread belief that eating from smaller plates helps you control food portions and feel fuller, Scientific American reports.

Past studies have shown that this mind trick, called the Delboeuf illusion, influences the amount of food that people eat. In one 2012 study, participants who were given larger bowls ended up eating more soup overall than those given smaller bowls.

However, researchers from Ben-Gurion University in Negev, Israel, concluded in a study published in the journal Appetite that the effectiveness of the illusion depends on how empty your stomach is. The team of scientists studied two groups of participants: one that ate three hours before the experiment, and another that ate one hour prior. When participants were shown images of pizzas on serving trays of varying sizes, the group that hadn’t eaten in several hours was more accurate in assessing the size of pizzas. In other words, the hungrier they were, the less likely they were to be fooled by the different trays.

However, both groups were equally tricked by the illusion when they were asked to estimate the size of non-food objects, such as black circles inside of white circles and hubcaps within tires. Researchers say this demonstrates that motivational factors, like appetite, affects how we perceive food. The findings also dovetail with the results of an earlier study, which concluded that overweight people are less likely to fall for the illusion than people of a normal weight.

So go ahead and get a large plate every now and then. At the very least, it may save you a second trip to the buffet table.

[h/t Scientific American]

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