Robert Boyle was born on January 25, 1627 in Lismore Castle, County of Waterford, Ireland. He was an Anglo-Irish natural philosopher, chemist, physicist and dabbled in many other areas of study. He published the book The Sceptical Chymist in 1661, and many consider him and his work as the foundation of modern chemistry. He was a very devout Anglican, and published numerous works in this area as well.
One of Boyle’s most famous discoveries was to become the first of the gas laws, relating the pressure of a gas to its volume. With Robert Hooke, a young university student as his laboratory assistant, Boyle began experimenting with air. Together they made their first great discovery, now known as Boyle’s Law.
The experiment was performed using a ‘J’ shaped glass tube sealed on the shorter leg, and open to atmosphere on the longer leg. Quicksilver (mercury) was poured into the tube, such that the level was equal on each side. The volume of the trapped air was noted. Additional mercury was poured into the tube and it was observed that the mercury did not stay level, and measurements of the heights on each tube leg were recorded. The height difference of the mercury is effectively a measure of the pressure of the trapped air. Boyle, through the experiment and the data, discovered a relationship between the volume and the pressure of air. The data as published, is shown below.
Boyle noticed the pressure times the volume of air for the initial condition equaled the pressure times the volume at any other mercury height.
Known as Boyle’s Law – P ∝ 1/V, pressure is proportional to the inverse of the volume
Alternately, PV = k, pressure times volume is equal to a constant
For comparing the same substance under two different sets of conditions, the law can be expressed as P1V1 = P2V2
Of note is that Boyle’s Law, combined with Charles’s law and Gay-Lussac’s Law formed the combined gas law, and in combination with Avogadro’s law is the basis for the ideal gas law – PV=nRT, which include temperature, the amount of the substance, and the ideal gas constant to the mix.
It is noted that Boyle credited fellow scientist Richard Towneley for making the connection between the pressure of a gas and volume, but Boyle’s experiments and observations using the ‘J’ tube confirmed Towneley’s predictions, and the rest as they say is history.
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Experiment Data from the book New Experiments Physico-Mechanicall, Touching the Spring of the Air, and Its Effects (1660)