When we first came across pockets of gases underground, what did the process of us actually recognizing these things look like? Did we know what to look for?
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Helium was not discovered on earth. It was discovered in the sun (the name is from the Greek for sun). It was discovered from the spectral lines it produces. When light shines through a gas certain parts of the spectrum of are reduced or increased. These are specific to each gas. We knew what the lines were for hydrogen and it was noticed there were lines that didn’t match hydrogen’s so there was another element in the sun.
By accident.
Helium was discovered in the late 1800s when scientists pointed spectrometers at the sun during an eclipse and saw a line they’d never seen before. Later in the 1800s it was successfully separated from clevetite, an ore containing uranium. One of the products of uranium decay is helium.
We don’t know when natural gas was discovered precisely, but the French encountered Native Americans setting it on fire in the 1600s.
Helium was not discovered on earth. It was discovered in the sun (the name is from the Greek for sun). It was discovered from the spectral lines it produces. When light shines through a gas certain parts of the spectrum of are reduced or increased. These are specific to each gas. We knew what the lines were for hydrogen and it was noticed there were lines that didn’t match hydrogen’s so there was another element in the sun.
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By accident.
Helium was discovered in the late 1800s when scientists pointed spectrometers at the sun during an eclipse and saw a line they’d never seen before. Later in the 1800s it was successfully separated from clevetite, an ore containing uranium. One of the products of uranium decay is helium.
We don’t know when natural gas was discovered precisely, but the French encountered Native Americans setting it on fire in the 1600s.
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Start with air. Stick a candle in a dish containing water, light it, then put a jar over the candle. The candle burns for a bit, then it goes out. As that happens, some of the water in the dish gets sucked up into the jar. Repeat a few times, and you will see that the part of the air that is used up when the candle burns is always about 20% by volume. Put a mouse in the jar with the burning candle and it dies when the candle does. So you have determined that ~20% of the air around us is used by both combustion and respiration.
Scientists had discovered that blowing air from the lungs through limewater turned it cloudy (carbon dioxide reacts to form calcium carbonate). The gas left after burning a candle did the same, as did the gas evolved from vinegar and soda bicarbonate. So all those things seemed to be the same gas (carbon dioxide).
Using limewater to remove carbon dioxide from air with oxygen also removed left something that made up about 80% of normal air. This took much longer to isolate and characterize, because nitrogen gas is not very reactive. It didn’t support combustion or respiration.
Gases evolved from chemical reactions were compared with known gases – some exploded (hydrogen), some were colored and noxious (chlorine).
The history of chemistry is full of simple experiments performed with available materials, comparing results to understand the natural world around them.
Start with air. Stick a candle in a dish containing water, light it, then put a jar over the candle. The candle burns for a bit, then it goes out. As that happens, some of the water in the dish gets sucked up into the jar. Repeat a few times, and you will see that the part of the air that is used up when the candle burns is always about 20% by volume. Put a mouse in the jar with the burning candle and it dies when the candle does. So you have determined that ~20% of the air around us is used by both combustion and respiration.
Scientists had discovered that blowing air from the lungs through limewater turned it cloudy (carbon dioxide reacts to form calcium carbonate). The gas left after burning a candle did the same, as did the gas evolved from vinegar and soda bicarbonate. So all those things seemed to be the same gas (carbon dioxide).
Using limewater to remove carbon dioxide from air with oxygen also removed left something that made up about 80% of normal air. This took much longer to isolate and characterize, because nitrogen gas is not very reactive. It didn’t support combustion or respiration.
Gases evolved from chemical reactions were compared with known gases – some exploded (hydrogen), some were colored and noxious (chlorine).
The history of chemistry is full of simple experiments performed with available materials, comparing results to understand the natural world around them.
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