Until the 1770s, air purity was tested by means of the barometer, or by measuring the time of survival of animals enclosed in glass vessels.

In 1772, the English theologian and natural philosopher Joseph Priestley observed that nitrous gas—which he referred to as "nitrous air"—significantly reduced the quantity of regular air with which it was mixed, producing an effervescence accompanied by steam and heat.

The reaction caused part of the atmospheric air—called "dephlogisticated air"—to disappear. Priestley accordingly suggested using the reaction to measure air purity: the greater the volume contraction, which was proportional to the absorption of atmospheric air, the higher the initial quality of the air.

In 1774, Priestley, while heating red mercury oxide to decompose it, identified a new gas capable of maintaining a lively combustion: oxygen. Applying the nitrous-air test to the new gas, Priestley obtained an even greater volume contraction than with atmospheric air. He was thus now able to calculate the amount of pure air contained in a given sample of ordinary air.

In 1775, Marsilio Landriani used this research as a starting point for the construction of a sophisticated instrument that he named "eudiometer." The purpose of the device was to measure the healthiness of air. In the same period, Felice Fontana built a similar instrument and, toward 1777, Alessandro Volta devised simpler and more accurate eudiometers. Even Antoine-Laurent Lavoisier took an interest in methods for measuring the goodness of air. In the nineteenth century, eudiometry also became a technique with social implications.