Tag: The Sceptical Chymist

People of Interest: Robert Boyle – 1627 to 1691

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Being in the compressed air industry for over 35 years, you come across many interesting people from the past that have created laws that we are still using today.   Robert Boyle is one of those people.  He was born on January 25, 1627 in Lismore Castle in Ireland.  He published the book “The Sceptical Chymist” in 1661, and many considered his work to be the foundation of modern chemistry.  He dabbled in many areas of study, but with a young university student, Robert Hooke, they found 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.  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 of each tube leg were recorded.  The height difference of the mercury is effectively a measure of the pressure of the trapped air.  Through the experiment and the data, Boyle 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.  So, the pressure is proportional to the inverse of the volume, Equation 1.

Equation 1: P ∝ 1/V

Or P * V = k (a constant)

For comparing the same substance under two different sets of conditions, Boyle’s law can be expressed as Equation 2.

Equation 2:  P1 * V1 = P2 * V2

Equation 2 looks very familiar.  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. Combining Boyle’s Law with Charles’s Law, Gay-Lussac’s Law, and Avogadro’s Law; you will have the basis and creation of the ideal gas law;

Equation 3:   P * V = n * R * T

which includes the major factors that affect a gas; temperature, pressure, volume, the amount of the gas, and the ideal gas constant.

Robert Boyle passed away on December 31st, 1691, and from his work, EXAIR uses the pressure and volume of compressed air for our Intelligent Compressed Air® Products to make them efficient, safe, and effective.  If you would like to speak more about how EXAIR can benefit your pneumatic system, one of our Application Engineers can help you determine the best solution.

John Ball
Application Engineer
Email: johnball@exair.com
Twitter: @EXAIR_jb

Robert Boyle image courtesy of Skara Kommun, Creative Commons License

People of Interest: Robert Boyle – January 25, 1627 – December 31, 1691

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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.

Robert Boyle

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.

J-Tube 2
Boyle used a ‘J’ Tube – Sealed on the Short End, and Open at the Long End

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's Data

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.

If you would like to talk about compressed air or any of the EXAIR Intelligent Compressed Air® Products, feel free to contact EXAIR and myself or one of our Application Engineers can help you determine the best solution.

Brian Bergmann
Application Engineer

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Experiment Data from the book New Experiments Physico-Mechanicall, Touching the Spring of the Air, and Its Effects (1660)