Robert Boyle

1627-1691

Irish Chemist and Physicist

Robert Boyle never earned a college degree. As a physicist, however, he performed some of the earliest experiments with gases. As a chemist, he helped to separate the science of chemistry from its roots in alchemy and, for this reason, is sometimes known as the father of chemistry.

Boyle was born in Ireland in 1627. He was the fourteenth child of a wealthy and aristocratic family. By the time he was eight years old, he was already studying Latin and Greek. From 1639 to 1644, beginning when he was eleven, he traveled throughout Europe while being taught by a tutor. The following decade, Boyle lived partly in England and partly on his estates in Ireland. His father had died by this time, and Boyle's inherited wealth gave him the money and the freedom to pursue scientific experiments.

From 1656 to 1668, he resided at the University of Oxford. (He was neither a student nor a professor, however.) There, Boyle participated in meetings of scientists who favored experimentation over logic alone. This group was called the Invisible College. In 1663, the group was officially recognized by King Charles II and was renamed the Royal Society—the first scientific society of England. Like other members of this group, Boyle believed that all experimental results should be clearly and quickly reported so that other scientists could profit from them.

At Oxford, Boyle performed some of the first experiments on gases. One of his assistants was Robert Hooke (1635-1703), who would eventually be the first scientist to describe cells. Together, Boyle and Hooke constructed an air pump. With this pump, Boyle could produce a vacuum in a sealed container. Boyle used his vacuum chamber to discover several processes that require the presence of air. By placing a ticking clock in the chamber, for example, Boyle showed that sound does not travel through a vacuum. Instead, the sound of the clock faded away as air was withdrawn by the pump. In addition, Boyle demonstrated that a bird can live for only a short time in a vacuum, showing that air is necessary for respiration. He also showed that air is required for combustion. In this experiment, he placed a red-hot iron plate in a vacuum and dropped a piece of sulfur on it. The sulfur did not burst into flames until air was allowed into the chamber. He described his findings in a book published in 1660, titled New Experiments Physio-Mechanicall, Touching the Spring of the Air and its Effects.

During his experiments, Boyle found that air is compressible. In 1661, he reported what is now known as Boyle's law, which states that at a constant temperature, the volume of a gas is inversely proportional to its pressure. In other words, as the volume of a gas decreases, its pressure increases. Because of air's compressibility, Boyle came to the conclusion that air is not a continuous substance, but consists of individual particles separated by empty space.

Boyle's interests included not only physics, but also chemistry. In 1661, he published The Sceptical Chymist. This book helped to transform alchemy into chemistry. Alchemy was a combination of science, religion, and philosophy whose chief goals included the creation of gold from other metals.

Most alchemists accepted a theory of matter that was based on four elements (earth, air, fire, and water) or three principles (salt, sulfur, and mercury). Boyle, however, proposed a theory of matter that eventually evolved into the modern theory of chemical elements. The alchemists saw elements as mystical substances. Boyle, on the other hand, believed that elements could only be identified by experiment. To Boyle, any substance that could not be broken down into simpler substances was an element. He did not necessarily reject the alchemists' elements, but he wanted them to be established by experiment. He did believe, however, that the number of elements might be much larger than three or four. (Today, more than 100 elements have been identified.)

Boyle also suggested a method of distinguishing between acids and bases that eventually led to the use of indicators. An indicator is a chemical that changes color as the acidity of a solution changes. For example, Boyle described how blue solutions obtained from plants, such as syrup of violets, are turned red by acids and green by bases. He also noticed that some solutions did not cause syrup of violets to change color. He called these solutions neutral. (It had earlier been thought that all solutions are either acids or bases.) In 1664, Boyle published Experimental History of Colors in which he described his work with acid-base indicators.

In 1680, Boyle was elected president of the Royal Society although he turned down the position. He became quite well known as a scientist during his lifetime and is considered by some to have established the science of chemistry.

STACEY R. MURRAY