Julien-François Jeannel

Resumo

Julien-François Jeannel (1814-1896) was a French physician and pharmacist who studied the assimilation of food in living organisms, particularly calomel; the chemistry of iron sesquioxide; the production of nitrates and nitrites in nature; the phenomenon of supersaturation and its use in crystallization and heat storage; the physical and chemical properties of sodium acetate; and more. He found that food assimilation was preceded by the formation of an emulsion, highly favored by alkaline carbonates, and that Hg(I) was transformed into Hg(II), the action of which was mitigated by albumin and fatty material. In the presence of water and HCl, iron sesquioxide hydrate transformed into iron sesquioxide chloride, ferric chloroxide, Fe₂Cl₃·9Fe₂O₃, highly soluble in water. Jeannel postulated that nitrates and nitrites were formed naturally in the topsoil upon contact with air, that it was possible to feed plants with suitable mineral solutions providing them with the solid elements needed to grow, and that plants vegetated much better in pure sand than in loam. Jeannel demonstrated that supersaturation and crystallization were not caused by particles floating in the air but by seeding with crystals of the same compound or solid bars. He also suggested that sodium acetate could be used to store solar energy.