One of the mysteries of the English language finally explained.
Definition of aerometric in English:
aerometric
adjective
1Of or relating to a method for measuring the density or relative density of a liquid, especially milk and beer, by means of a set of small hollow spheres or ‘beads’.
2Of or relating to the measurement of the mechanical properties of air and other gases; (in later use chiefly) of or relating to the measurement of air pollutants.
Origin
Early 19th century; earliest use found in The Farmer's Magazine. From aero- + -metric, after aerometer, aerometry.