Who Discovered the Composition of Water: The Chemists Who Unlocked Its Secret
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The chemical composition of water is one part oxygen and two parts hydrogen — the formula H₂O — a discovery made independently by several bold chemists working almost at the same time. In the distant past, when people did not yet know that the planet Earth was shaped like a sphere, but pictured it as a disc or even a floating rectangle, fire, air, earth and water were regarded as the four basic elements of the universe.
Who discovered oxygen and hydrogen?
Oxygen and hydrogen were discovered by a small group of eighteenth-century chemists who, working separately, arrived at similar conclusions. Once chemists had pushed the alchemists and sorcerers away from the retorts, the family of elements grew rapidly. A hundred years ago it counted only about 60 members; today, including the artificially produced ones, the total has reached one hundred.
The name, chemical symbol, atomic weight and atomic number of every element can be found in any chemistry table. Only the names of the "ancestors" — the people who found them — have vanished from those tables.
The chemists credited with first isolating oxygen and hydrogen were:
- The French chemist Antoine Laurent Lavoisier. He managed a saltpetre and gunpowder works and later, after the victory of the French bourgeois revolution, became commissioner of the national treasury and one of the most influential men in France.
- The English chemist Henry Cavendish, born into an old ducal family, who devoted a significant share of his fortune to science.
- Cavendish's compatriot, Joseph Priestley. He was a clergyman. As an ardent supporter of the French Revolution, Priestley was driven out of England and fled to America.
- The renowned Swedish chemist Carl Wilhelm Scheele, a pharmacist.
Those are their names. Now, what exactly did they do?
How is oxygen found in water and air?
Oxygen is present in both water and air, and it was first identified through a series of experiments carried out by Lavoisier, Priestley and Scheele. In chemistry it is denoted by the letter "O". When people said:
There is no life without water,
that saying did not yet explain what, precisely, gives water its life-giving power. Now the question can be answered. The life-giving power of water lies in oxygen. Oxygen is the most important element of the air envelope surrounding the Earth.
Without oxygen, life goes out like the flame of a candle placed under a glass jar. Even the largest fire dies down if the burning objects are smothered with sand, cutting off their supply of oxygen.
In just the same way, the human body uses the energy of the nutrients we consume. The air we breathe is needed so that the "stove" — our body — burns well, for our body must maintain a certain temperature. When we exhale, we release water as vapour along with the products of combustion.
How was hydrogen discovered?
Hydrogen was discovered by Lavoisier almost at the same moment as by Cavendish, who had likewise broken water down into its component parts. This element was given the name "Hydrogenium", which means:
I produce water.
Hydrogen is denoted by the letter "H". Let us test once more whether hydrogen really is part of the composition of water. Fill a test tube with ice and warm it over the flame of a spirit lamp. (Spirit, like any alcohol, is rich in hydrogen.)
And what do we see? The outer surface of the test tube becomes covered as if with dew. Or hold a clean knife over a candle flame — the knife, too, will be covered with drops of water. Where does that water come from? The water arises from the flame. So fire is a source of water! This is not a new discovery, and yet it is astonishing.
A chemist would put it this way: when hydrogen burns — in other words, when hydrogen combines with oxygen — water vapour is formed. That is why the test tube and the knife become covered with drops of water. This is how the composition of water was discovered. So hydrogen — which is 16 times lighter than oxygen and 14 times lighter than air — burns! And in doing so it releases a great deal of heat.
Balloons used to be filled with hydrogen. This was very dangerous. Today helium is used instead of hydrogen. We can also answer a second question:
Why does water not burn?
This question seems so simple that at first we did not even ask it. Most people would say:
Water is wet, and that is why it does not burn.
That is wrong. Petrol is also "wet", but you had better not test whether it burns! Water does not burn because it is itself the product of burning. It is, so to speak, the "liquid ash" of hydrogen. That is why water extinguishes fire no worse than sand does.
