Henry Cavendish: The scientist who discovered hydrogen and weighed the Earth

Henry Cavendish, a resounding name in the world of science, is remembered for his pioneering contributions to 18th-century chemistry and physics. Born in 1731 in Nice, France, Cavendish was a British scientist whose life and work left an indelible mark on the history of science.

The Life of a Reclusive Scientist

Henry Cavendish came from a British aristocratic family. His grandfather, the 2nd Duke of Devonshire, and his father, Lord Charles Cavendish, were prominent figures in society. Henry studied at Peterhouse College, Cambridge, although he left university without earning a degree. His introverted nature and aversion to public attention led him to live a life of seclusion, devoted almost exclusively to scientific research.

The Discovery of Hydrogen

One of Cavendish’s most significant achievements was the discovery of hydrogen in 1766. Through his experiments, he demonstrated that this gas, which he called “inflammable air,” was produced when metals reacted with acids. Cavendish identified the properties of hydrogen and, in doing so, laid the groundwork for the development of modern chemistry. Later, chemist Antoine Lavoisier would confirm that hydrogen is an essential element in the formation of water, thus changing the scientific understanding of the chemical composition of water.

(Photo: Wikimedia Commons)

The Density of the Earth: The Cavendish Experiment

Another of Cavendish’s notable achievements was his experiment to measure the density of the Earth, known as the Cavendish Experiment. Using a torsion balance, he designed an ingenious apparatus to measure the gravitational force between masses of lead. His experiment, conducted in 1797–1798, was the first to allow the average density of the Earth to be calculated, providing a value close to the one currently accepted. This experiment not only allowed the Earth to be “weighed”, but also provided a better understanding of the gravitational constant.

Other Scientific Contributions

In addition to his best-known discoveries, Cavendish made important contributions in other fields:

• Electricity: Cavendish studied the conductivity and electrical properties of various materials, anticipating Coulomb’s Law and anticipating concepts that would be fundamental to the development of electrical theory.
• Heat and Gases: He conducted experiments on the nature of heat and the properties of gases, contributing to thermodynamics and the kinetic theory of gases.
• Water Chemistry: His investigations into the composition of water showed that it was composed of hydrogen and oxygen, supporting Lavoisier’s theory on the chemistry of water.

Legacy and Recognitions

Although Cavendish was an extremely private man, his scientific legacy has been immense. His works, though mostly unpublished during his lifetime, were compiled and disseminated posthumously, revealing the breadth of his genius. In honor of his contributions, the unit of electrical capacitance in the International System of Units was named the “farad” (Farad) after Michael Faraday, who was influenced by Cavendish’s work. In addition, several scientific institutions and awards bear his name.