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| A composition pie chart of air:nitrogen (N2) 78%, oxygen (O2) 21%, as well as argon (Ar), neon (Ne), helium (He), methane (CH4), krypton (Kr), hydrogen (H2), nitrous oxide (N2O), and xenon (Xe), in smaller percentages, embedded in a system of about forty percent water vapor (H20) |
“The ‘air’ is nothing other than a fume or evaporation coming from the earth, which it surrounds with a ‘fixed and definite weight’. It penetrates everything that is not already filled with some other substance, is carried with the earth is it executes both its daily and annual motions, and, along with the earth, constitutes, as it were, a single body. We can ‘weight the air’ confined to a glass vessel. The weight is given by how much lighter the glass is once it has been evacuated. A receiver, e.g., of the sort that medical people use to distill water, is about three or four lobt [small coin] lighter after the extraction of the air.”— Otto Guericke (1656), “Letter to Gaspar Schott”, Jun 18 [1]
