Between 1777 and 1789, Antoine Laurent LAVOISIER, always encouraged by his wife Marie Anne Pierrette, discovered that atmosphere was constituted by two gas like fluids "Vital Air" for 25%, and Nitrogen for 75%. He also discovered that "Vital air"was Oxygen
Jacques Louis David, Metropolitan Museum of Art, New Yotrk
We breathe Nitrogen (perhaps useless, perhaps not), oxygen (essential, but breathing too high concentrations for too long is dangerous), Argon (one of what are called "rare gases"), and carbon dioxide (concentration 30 times lower than that of Argon)
Composition of atmospheric air
French scientist, Lavoisier played a key role in discovering thr proportions of oxygen and nitrogen. He also realized that carbon dioxide was present, but in much lower concentrations.
Laurent and Marie-Anne Pierrette Lavoisier