John Mayow (1643–1679) was an early researcher of respiration and the nature of air. Mayow published tracts on respiration and rickets while studying at Oxford in 1668; in 1674 these were edited and reprinted with three other tracts (De sal-nitro et spiritu nitro-aereo, De respiratione foetus in utero et ovo, and De motu musculari et spiritibus animalibus) as Tractatus quinque medico-physici.

This work establishes a theory of combustion supported by thoroughly detailed experiments. Mayow concludes that air consists of at least two constituents, the "nitro-aerial" spirit, which supports combustion and respiration, and the "sal-nitro", an inert volume present after combustion or respiration. Despite preceding the discovery of oxygen by a century, Mayow provides a semi-accurate anatomical description of the mechanism of respiration.

Digitization includes the engraved frontispiece portrait of Mayow, the title page, and 6 folding copperplates.