In early 1791, Volta began a systematic study of the physical properties of gases. Through a long series of experiments, he determined, well ahead of Gay-Lussac, the law of uniform expansion of air as a function of temperature.
Volta’s interest stemmed from the significant divergence between the results obtained by leading European scholars. Opinions on the expansion of air varied considerably, especially at high temperatures. To clarify the issue, Volta decided to subject the phenomenon to rigorous and systematic experimental analysis.
From his observations, Volta concludes that the expansion of air is almost uniform and proportional to increases in temperature throughout the entire range between freezing and boiling point. This conclusion anticipates subsequent formulations and extends the validity of the principle even beyond these limits.
At the same time, Volta devoted himself to physical pneumatics. In 1793, he obtained more accurate measurements of the isobaric expansion coefficient of air than those published by Gay-Lussac years later. In 1794, he also measured the vapour pressure of water, anticipating and surpassing Dalton’s results in terms of accuracy.
In 1794, the Royal Society of London awarded Volta the Copley Medal, recognising the value of his research into electrical and pneumatic phenomena and the rigour of his experimental method.
In 1927, during the International Congress of Physics, the scientific community formally recognised Volta’s priority on the law of isobaric expansion of air, distinguishing it from Gay-Lussac’s law, which applies to all gases. This recognition restored Volta to his rightful place in the history of gas physics.
