page_title: Camille Matignon
section_title: Research
hierarchical_section_title: Camille Matignon / Research
caption_attribution_description: Français&#160;: Carte postale photographique
context_page_description: Arthème Camille Matignon was a French chemist noted for his work in thermochemistry. He was a member of the Académie des Sciences, President of the French Chemical Society and an honorary Fellow of the British Chemical Society.
context_section_description: In his early years, Matignon studied heat of combustion for major gaseous hydrocarbons and standard enthalpy of formation for ethanol, formic acid, acetic acid and various sugars. He extended this work to a family of 70 urea derivatives and formulated several thermochemical rules, for example, that the replacement of hydrogen attached to nitrogen by an alkyl radical increases the heat of combustion more than when the replacement is carried out at a carbon atom. This led to such practical conclusions as nitric esters are more powerful explosives than nitro-derivatives. Those urea studies aimed to understand the processes occurring in living organisms and hinted that formic acid and urea should react at ambient conditions and form formylurea.
  After his return to the Collège de France in 1898 Matignon generalised his work to the thermodynamics of chemical systems and formulated an empirical law which Walther Nernst named the "Le Chatelier-Matignon rule". The law stated that for an equilibrated system of one gaseous
  and one or more solid phases the ratio of the heat Q evolved at constant pressure and of the temperature T at which the gaseous pressure is equal one atmosphere is Q/T = 32. This law can be applied to such cases as sublimation and dissociation of calcium carbonate and can predict whether a chemical reaction will proceed and whether it will be reversible. 
  At the Sorbonne, Matignon mostly worked on rare-earth elements. He was heating the metal oxide with magnesium to produce the pure metal in an atmosphere of a certain gas, and demonstrated that most rare earths easily react with nitrogen and absorb hydrogen. He also studied the chemistry of numerous rare-earth salts and revealed that samarium can have the valence of two in addition to the common 3+ state. For other metals, Matignon showed that technical-grade zinc, aluminium and ferromanganese powders always contain some nitrogen (e.g. 0.2–0.4% for zinc). 
  World War I urged most chemists to work on urgent technological problems, and Matignon had studied the water-sodium sulfate-ammonium system aiming for the production of sulfuric acid. He also worked on the stability of the ammonium carbonate-urea system, which was important for fertilizers, and discovered an iron-alumina catalyst for the synthesis of ammonia. By applying an oxidation reaction to a cargo of sugar spoiled by seawater he managed to convert it into oxalic acid. Matignon also tried to design recycling procedures for waste products of grape processing and brandy distillation.
caption: Collège de France. Professor Matignon (Bibliothèque de la Sorbonne, NuBIS)
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