Claude Louis Berthollet | Biography

Claude Berthollet was born into a French family living in the Savoy, a region of France that was then part of Italy. Although the family 's finances had declined, his parents were able to send him to a college in Turin, Italy, where he earned his medical degree in 1768. A few years later, he moved to Paris, France, where he studied chemistry and continued his medical work.

In 1784 Berthollet became director of the Gobelins textile factory. There he began research on the bleaching properties ofchlorine, which had been discovered by Carl Wilhelm Scheele in 1774. Like Scheele, Berthollet originally believed that chlorine was a compound of oxygen rather than an element. Through other experiments he determined the composition of ammonia (NH₃ ) and that the compound potassium chlorate explodes when mixed with carbon. He thought that this compound might replace conventional substances used to make gunpowder. In 1788 Berthollet attempted a public demonstration of this new, more powerful gunpowder, but it ended in disaster. The mixture proved to be too explosive, and four people in the crowd were killed on the spot.

When he first came to Paris, Berthollet met Antoine-Laurent Lavoisier, whose reputation and influence were then at their peak. Berthollet joined Lavoisier's team of chemists in developing a new, logical system of chemical nomenclature, which was proposed in 1787 and quickly adopted by chemists worldwide. However, Berthollet disagreed with Lavoisier's theory that all acids contain oxygen; Berthollet's analysis of prussic acid (hydrocyanic acid, or HCN) eventually proved Lavoisier's theory wrong.

Berthollet's career survived the French Revolution, which began in 1789, and in the 1790s, Berthollet became scientific advisor and chemistry teacher to Napoleon Bonaparte (1769-1821). On a trip to Egypt with Napoleon in 1798, Berthollet noticed deposits of soda (sodium carbonate) on the shores of a saltwater lake. He concluded that the soda was formed because of prevailing physical conditions in the area. This was the beginning of Berthollet's theory that the speed of chemical reactions depends on more than just the attraction of one reactant to another. He determined that other factors such as the concentration of each reactant must also be considered. This idea, which Berthollet formally proposed in 1803, foreshadowed the fundamental law of mass action, which states that reaction speed depends on the masses of the reactants.

Berthollet also believed that the composition of a chemical compound depends on the masses of reactants, but this theory was proved wrong. Beginning in 1799, Berthollet carried on a friendly argument with fellow chemist Joseph Louis Proust, who maintained, correctly, that pure reactants always combine in the same proportions to produce exactly the same compound. Berthollet died in 1822.