William Henry (1774-1836): The Manchester Chemist Who Measured Dissolved Gases

Introduction

William Henry was an English physician and chemist from Manchester. He is remembered for Henry's law of gas solubility (1803), for being a close friend and supporter of John Dalton, and for his widely used textbook Elements of Experimental Chemistry. His legacy in one line: he showed that the quantity of gas dissolved in a liquid grows in direct proportion to the pressure of that gas.

Early Life and Family

Henry was born on 12 December 1774 in Manchester, England. His father, Thomas Henry, was an apothecary and manufacturing chemist who was a Fellow of the Royal Society and who became well known for producing magnesia (magnesium carbonate-based medicine) and for translating works of Lavoisier. The family was part of the lively scientific and intellectual circle of Manchester, which was one of the centres of the Industrial Revolution. William grew up among chemicals and books, and he helped in his father's business. His father's friends included important people of the Manchester Literary and Philosophical Society.

Education and Mentors

Henry was educated in Manchester and then went to the University of Edinburgh to study medicine. There he came under the influence of the famous chemist Joseph Black's tradition, as taught in Edinburgh, and he studied chemistry and medicine. A health problem interrupted his studies, and he returned to Manchester to work with his father, but he went back to Edinburgh and took his MD degree in 1807. He was a student of the strong Scottish school in which chemistry and medicine were studied together. Manchester provided his other schooling: the Literary and Philosophical Society, where he met Dalton.

Career Timeline

Major Scientific Contributions

• Henry's law (1803): The mass of a gas dissolved in a liquid is proportional to its pressure, and each gas in a mixture dissolves according to its own partial pressure. See our discovery blog for the equations and applications.
• Support for Dalton's atomic theory: Henry's results fitted Dalton's law of partial pressures. Henry also defended Dalton's atomic ideas, and he repeated and confirmed Dalton's experiments, including the analysis of methane and ethylene. This helped the acceptance of atomic theory in Britain.
• Composition of hydrocarbons: He analysed "light carburetted hydrogen" (methane) and "heavy carburetted hydrogen" (ethylene) and the gases of coal gas. His analyses used combustion with oxygen and measured the volume of CO₂ formed. Example: CH₄ + 2 O₂ → CO₂ + 2 H₂O.
• Elements of Experimental Chemistry: A textbook that went through many editions and was reprinted in the United States and Europe. It was among the most popular chemistry texts of its time.
• Public health chemistry: He investigated how heating clothes and goods to a suitable temperature could kill infection (disinfection), a topic of public interest in disease control at the time.

Awards, Honours and Nobel Prize

• Fellow of the Royal Society (1808).
• Copley Medal of the Royal Society (1808).
• Active member and leader of the Manchester Literary and Philosophical Society.
• No Nobel Prize, since he died long before the prizes began in 1901.

Personality, Struggles and Lesser-Known Facts

• He was a close friend and admirer of John Dalton, and gave him support when atomic theory was still doubted. Dalton used Henry's solubility data in his own thinking on gas mixtures.
• Henry suffered from poor health through much of his life, including a lot of pain, which sometimes limited his work.
• He had a successful chemical business in Manchester, in which science and trade went together, as with his father.
• His textbook carried sections on practical work, so a student could repeat the experiments. This was a modern approach for the time.
• His son, William Charles Henry, also became a chemist, and wrote a biography of Dalton.
• He was a physician by training, so his interest in the gases in blood, respiration and medicine was natural.

Legacy and Influence on Modern Chemistry

Henry's law is today taught in every chemistry course. It helps explain how oxygen enters blood in the lungs, how soft drinks are made, and why divers must follow decompression tables. In environmental chemistry, Henry's law constants are used to predict how pollutants such as CO₂, SO₂ and volatile organic compounds partition between air and water in lakes, rivers and clouds. In chemical engineering, absorption towers use the law for scrubbing gases. For Indian students, the law is a regular source of questions in Class 12 (Solutions), JAM, NET and GATE, and the idea of dissolved oxygen is important for water quality in India's rivers and ponds.

Lessons for Students

• Measure first, theorise later. Henry's law came from experiments with pressure and volume.
• Collaboration helps. His friendship with Dalton helped both.
• Write clearly. His textbook taught thousands of students.
• Science can serve health. Disinfection and respiration studies had public benefit.
• Persist despite illness. He worked through years of pain.

FAQ

Who was William Henry's famous friend?

John Dalton, the atomic theorist, who lived and worked in Manchester.

Was William Henry a doctor?

Yes, he took his MD at Edinburgh in 1807.

What prize did Henry receive?

The Copley Medal of the Royal Society in 1808.

What is Henry's law used for today?

To calculate gas solubility in carbonated drinks, blood and natural waters, and in industrial gas absorption.

Published by ABC Chemistry — IIT-JAM | CSIR-NET | GATE Chemistry Coaching. Visit abcchemistry.com