NaCl(aq), NaCl(aq), C C C C C C C was the equation that the chemist was thinking of when he knew he needed a vacation. What did it mean?

Saline, saline, over the seven Cs

Antoine-Laurent de Lavoisier

Few things are as important as water, which we know is made of oxygen and hydrogen. Did you know that Antoine Lavoisier was the discoverer of both elements?

Contributions to Science

Antoine-Laurent de Lavoisier is one of the most important scientists in the history of chemistry. He discovered elements, formulated a basic law of chemistry and helped create the metric system.

During his time, people believed that when an object burns, a mysterious substance called ‘phlogiston’ was released. This was called the ‘phlogiston theory’. Lavoisier’s experiments demonstrated the contrary, i.e. when something burned, it actually absorbed something from the air, instead of releasing anything. He later named the ‘something’ from the air as oxygen, when he found that it combined with other chemicals to form acid. (In Greek, ‘oxy’ means sharp, referring to the sharp taste of acids.)

Henry Cavendish had earlier isolated hydrogen, but he called it inflammable air. Lavoisier showed that this inflammable air burned to form a colourless liquid, which turned out to be water. The Greek word for water is ‘hydro’, so the air that burned to form water was hydrogen!

Lavoisier was known for his painstaking attention to detail. Whenever he made a chemical reaction, he weighed all the substances carefully before and after the reaction. He discovered that in a chemical reaction, though substances may change their chemical nature, their total mass remains the same. This is called the law of conservation of mass.

His love for accuracy led to the formulation of the metric system of weights and measures – which is still in use today.

Lavoisier’s attention to detail and habit of recording everything is perhaps his most important contribution – for that is now the way science is done.


Lavoiser was born on 26 August 1743 in a wealthy Parisian family. He studied at the Collège Mazarin from 1754 to 1761. His interest in chemistry was developed as he read the works of Étienne Condillac. In 1769, he set about making a geological map of France, which was important for that country’s industrial development. In 1769, he took a government position as a tax collector in the government of King Louis XVI.

In 1771, he married Marie-Anne Pierette Paulze, who is considered as an eminent scientist in her own right. She translated the works of many scientists from English and German into French, and later on, with her husband, published the Traité élémentaire de chimie, often considered the first comprehensive book on the subject.

In 1789, King Louis XVI was overthrown in the French Revolution. As Lavoisier had been a tax collector, he earned the wrath of the revolutionaries, who executed him on 8 May 1794.


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