Jeremias Benjamin Richter

Law of Definite Proportions (Jeremias Benjamin Richter)

Evidence for the existence of atoms was the law of definite proportions proposed by Jeremias Benjamin Richter in 1792. Richter found that the ratio by weight of the compounds consumed in a chemical reaction was always the same. It took 615 parts by weight of magnesia (MgO), for example, to neutralize 1000 parts by weight of sulfuric acid. A few years later, when Proust reported his work on the constant composition of chemical compounds, the time was ripe for the reinvention of an atomic theory. The laws of definite proportions and constant composition do not prove that atoms exist, but they are difficult to explain without assuming that chemical compounds are formed when atoms combine in constant proportions.

The Origins of Stoichiometry (Jeremias Benjamin Richter)

Between 1792 and 1794 Jeremias Benjamin Richter published a three-volume summary of his work on the law of definite proportions. In this book Richter introduced the term stoichiometry, which he defined as the "art of chemical measurements, which has to deal with the laws according to which substances unite to form chemical compounds."

Richter was fascinated with the role of mathematics in chemistry. Unfortunately his writing style has been described as "obscure and clumsy." His work therefore had little impact until 1802, when it was summarized by Ernst Gottfried Fischer in terms of tables.