The Proclaimer (O.Fr. la voisier)

The Father of Chemistry Antoine Lavoisier ( ) was a taxman He was also a methodical scientist, who made careful, orderly measurements on weights, volumes and products of reaction using apparatus like the Gazometre His fundamental belief was that the weight of matter would be conserved through any reaction This concept led to our modern understanding of combustion and respiration involving the part of “common air” he called OXYGEN

The discovery of Oxygen: the demise of phlogiston In 1789 Lavoisier heated mercuric oxide in a closed system and measured the amount of oxygen gas liberated. He reversed the experiment by heating the mercury formed: it took up exactly the amount of oxygen previously made!

A Tale of Two Scientists Joseph Priestley was a social and religious revolutionary. In contrast he was rather a conservative chemist who believed in the incorrect phlogiston theory until the day he died Antoine Lavoisier was a respected member of the pre-revolutionary establishment in Paris. In contrast his radical scientific ideas gave birth to modern Chemistry In 1794 Priestley fled by ship to America while Lavoisier, aged 51, was executed in Paris

N names “Common Air” had now been established to consist partly of Oxygen and partly of Fixed Air The majority of it did not support life or combustion and was called: Foul Air (by Scheele) and, later, Noxious or Mephic Air (by Black’s student Daniel Rutherford in 1772) Azote (by Lavoisier in 1789) Nitrogène (by the industrial chemist and French government Minister, Jean Antoine Chaptal in 1790: He kept his head!) Stickstoff (i.e. literally “suffocating material” in Germanic nations)

The First Aeronomer Joseph Gay Lussac ( ) ascended in a balloon to 6-7km in 1802 He determined that the concentration of gaseous oxygen in the atmosphere remained constant (~20%) as a function of altitude In 1809 he showed that gases combine in very simple proportions by volume. This work inspired Avogadro in 1811…as we shall see next time

World Revolution and Order Revolution in America ( ) Storming of the Bastille (1789) United Irish Patriots rebellion (1798) Napoleon Bonaparte was captured in 1815 and order restored over Europe. The Industrial Revolution takes over based on careful measurement and sound principles

Art of the Time Goya’s: “Execution of the Defenders of Madrid, 3rd May, 1808” (1814)

Discovery: Gases take over from “airs” Oxygen, Hydrogen and many other gases discovered Conservation of Mass Law stated Oxidation and Reduction proposed One volume of Oxygen found to combine with exactly two volumes of Hydrogen to form Water The Science of Chemistry is born