This foundational treatise on chemistry begins by establishing the modern understanding of heat as a material substance called caloric, which acts as the primary repulsive force between particles. Lavoisier systematically demonstrates that the three states of matter—solid, liquid, and gas—depend entirely upon the proportion of caloric combined with a body, providing a unified framework for physical transformations.
The core of the work centers on the revolutionary mechanics of combustion. Through precise experiments, the author proves that burning is not the release of a mythical substance called phlogiston, but rather the rapid combination of a substance with the oxygen present in the atmosphere. By burning phosphorus, sulphur, charcoal, and various metals in pure oxygen, Lavoisier measures the precise weight gains and proves that the resulting substances are heavy oxyds or acids.
Water, long considered an immutable element, is rigorously dismantled and rebuilt. By passing steam over red-hot iron and charcoal, Lavoisier demonstrates that water is a compound of oxygen and hydrogen. He confirms this analysis synthetically by exploding these two gases together in precise proportions to recreate pure water, permanently removing water from the list of simple elements.
The work also addresses the composition of the atmosphere, separating it into respirable oxygen and non-respirable azote. Lavoisier shows that the former is the universal acidifying principle, essential for respiration and calcination, while the latter remains largely passive during these chemical interactions.
Building upon these principles, the author lays the groundwork for classifying a vast array of neutral salts. He explains how acids, formed by oxygenating simple radicals, combine with salifiable bases such as alkalies, earths, and metallic oxyds to produce orderly series of chemical compounds.
Finally, the treatise introduces a rational nomenclature designed to replace the obscure and contradictory alchemical terms of the past. By naming substances according to their actual constituent elements and degrees of oxygenation, Lavoisier provides chemistry with a clear, universal language that mirrors the true order of nature.
