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Joseph Priestley
Priestley preferred to observe qualitative changes in heat, colour, and particularly volume. His experiments tested "airs" for "their solubility in water, their power of supporting or extinguishing flame, whether they were respirable, how they behaved with acid and alkaline air, and with nitric oxide and inflammable air, and lastly how they were affected by the electric spark -
Antoine Lavoisier
In Methods of Chemical Nomenclature (1787), he invented the system of chemical nomenclature still largely in use today, including names such as sulfuric acid, sulfates, and sulfites. -
Humphry Davy
In 1815 Davy suggested that acids were substances that contained replaceable hydrogen %u2013 hydrogen that could be partly or totally replaced by metals. When acids reacted with metals they formed salts. Bases were substances that reacted with acids to form salts and water. These definitions worked well for most of the nineteenth century. -
Justus Von Liebig
This definition is proposed by Justus von Liebig circa 1838, based on his extensive works on the chemical composition of organic acids. This finished the doctrinal shift from oxygen-based acids to hydrogen-based acids, started by Davy. According to Liebig, an acid is a hydrogen-containing substance in which the hydrogen could be replaced by a metal. Liebig's definition, while completely empirical, remained in use for almost 50 years until the adoption of the Arrhenius definition. -
Svante August Arrhenius
Arrhenius began by assisting Edlund in his work on electromotive force measurements in spark discharges but soon moved to an interest of his own. This resulted in his thesis (1884) Recherches sur la conductibilit galvanique des lectrolytes (Investigations on the galvanic conductivity of electrolytes). From his results the author concluded that electrolytes, when dissolved in water, become to varying degrees split or dissociated into electrically opposite positive and negative ions. -
Johannes Nicolaus Brnsted
Brnsted's main achievement was the development of a valid concept of acids and bases in 1923, often referred to as the Brnsted theory of acids and bases. In Brnsted's concept, every acid is related to a conjugate base. The definition applies to all solvents and not just to water. -
Thomas Martin Lowry
Brnsted-Lowry theory (of acids and bases), Named after Johannes Nicolaus Bronsted (1879- 1947) and Thomas Martin Lowry (1874 - 1936). A theory that describes acids and bases in terms of the transfer of a proton from the acid to the base. This is the traditional view, which can be further elaborated by calculation of the pH of the resulting solution, which depends on the concentration of the oxonium ion. Common acids such as hydrochloric acid, nitric acid and sulphuric acid are all Bronsted acids
