Robert Boyle

The British chemist, physicist, and natural philosopher Robert Boyle (1627-1691) was a leading advocate of "corpuscular philosophy." He made important contributions to chemistry, pneumatics, and the theory of matter.

The seventh son and fourteenth child of the 1st Earl of Cork, Robert Boyle was born on Jan. 25, 1627, at Lismore Castle in County Cork, Ireland. His father was one of the richest and most powerful men in Ireland, and throughout his life Boyle enjoyed, in addition to his native talents, the advantages of position, family, and wealth. At the age of eight he was sent to school at Eton and then in 1638 to Geneva, Switzerland, where he was privately tutored for the next two years. Upon the death of his father, Boyle returned in 1644 to England, where after some initial delay he settled at the manor of Stalbridge in Dorsetshire, which he had inherited from his father.

Boyle devoted much time to study and writing, and although he wrote extensively on ethical and religious topics, he became increasingly interested in natural philosophy. He interested himself in nearly all aspects of physics, chemistry, medicine, and natural history, although it was chemistry that "bewitched" him and primarily occupied his time.

In 1652 Boyle left Stalbridge for Ireland, where 10 years of civil war had seriously disordered the family estates. During his stay he continued to pursue his scientific interests. In 1654 he settled in Oxford, then the scientific center of England. He there associated himself with a group interested in the "new learning." This group, including many of the leading scientific figures of the day, quickly recognized Boyle's exceptional abilities, and he became a regular participant in their activities, pursuing particularly his interest in chemistry.

Pneumatic Investigations

Soon after his arrival in Oxford, Boyle's researches took on an additional dimension. Having learned in 1657 of the vacuum pump recently invented by Otto von Guericke, Boyle immediately set Robert Hooke, his brillant assistant (and later an eminent scientist in his own right), the task of devising an improved version. Utilizing this improved pump Boyle immediately began a long series of investigations designed to test properties of the air and to clearly establish its physical nature. Boyle's first account of these "pneumatic" investigations was entitled New Experiments, Physico-Mechanical, Touching the Spring of the Air and Its Effects (1660). He continued his study of air and vacuum throughout the rest of his life, and although his experiments with the "Boyleian vacuum" (as it came to be known) were repeated by many, no one in the 17th century surpassed Boyle's ingenuity or technique.

Boyle made extensive studies of the elasticity of the air and of its necessity for various physical phenomena, such as combustion, the propagation of sound, and the survival of animals. He verified Galileo's conclusions about the behavior of falling bodies by studying the rate at which a light body fell, both in air and in a vacuum. By placing a Torricellian barometer in the receptacle of his pump, he also verified that it was indeed air pressure which supported the column of mercury. When his conclusions about the relationship between the pressure of the air and the weight of the mercury it would support were challenged, he produced a series of experiments demonstrating that for a given quantity of air the volume is inversely proportional to the pressure, a relationship now known as Boyle's law.

Corpuscular Philosophy

The Sceptical Chymist (1661), although one of Boyle's more theoretical works and suffering from his usual lack of organization, well illustrates his contention that all scientific investigation must be firmly based on experiment. Directing his attack at what he conceived as the erroneous foundations of contemporary chemical theory, he brought forth extensive experimental evidence to refute the prevailing Aristotelian and Paracelsian concepts of a small number of basic elements or principles to which all compounds could be reduced by chemical analysis. He demonstrated that common chemical substances when decomposed by heat not only failed to yield the requisite number of elements or principles, but that the number was a function of the techniques employed. Accordingly, he denied that elements or principles (as thus defined) had any real existence and sought to replace these older concepts of chemical change with what he termed the "corpuscular philosophy."

Although he emphasized the necessity of basing scientific research on experiment, Boyle was not a simple empiricist. Behind his more specific and detailed work was a general theory of the structure of matter; and his continued advocacy of the mechanical philosophy—that is, explanation in terms of matter and motion—was one of his most significant contributions. According to Boyle's corpuscular philosophy, God had originally formed matter in tiny particles of varying sizes and shapes. These particles tended to combine in groups or clusters which, because of their compactness, had a reasonably continuous existence and were the basic units of chemical and physical processes. Any change in the shape, size, or motion of these basic clusters altered the properties of the substance involved, although chemical reactions were generally conceived as involving primarily the association and dissociation of various clusters.

Boyle also made significant contributions to experimental chemistry. He made extensive studies of the calcination of metals, of combustion, and of the properties of acids and bases. He emphasized the application of physical techniques to chemical investigation and developed the use of chemical indicators which showed characteristic color changes in the presence of certain types of substances. His pioneering study of phosphorus, during which he discovered nearly all the properties known for the next two centuries, well illustrates the effectiveness of his experimental techniques.

Science and Religion

An influential public figure, Boyle was often at court and was among those who in 1662 used their influence to obtain a charter for the Royal Society. He was a charter member of the society, as well as one of its initial council members, and provided the society with two of its most influential early officials: Henry Oldenburg, who had been tutor to Boyle's nephew, was appointed the society's first secretary, and Robert Hooke became its first curator.

In 1668 Boyle moved to London. As a leading figure of English science and a member of a prominent family, he was offered numerous honors, including a peerage and a bishopric, all of which he declined, insisting that he preferred to remain a simple gentleman. In 1680 he even refused the presidency of the Royal Society on the grounds that his conscience was, as he said, "tender" about subscribing to the necessary oaths.

Throughout his life Boyle maintained a deep and pervasive religious commitment. As an active supporter of missionary work, he was appointed by the King the governor of the Corporation for Propagating the Gospel in New England. He was particularly concerned, however, with demonstrating that science and religion were not only reconcilable but in fact integrally related, and in his effort to promote this belief he produced numerous essays and tracts on religion and natural theology. He died on Dec. 30, 1691, and in addition to leaving much of his estate for the furtherance of various Christian endeavors, he provided in his will for the establishment of an annual series of sermons, in his words, "for proving the Christian Religion against notorious Infidels." These sermons, known as the Boyle Lectures, became by tradition one of the primary platforms for promoting the belief that in the study of nature could be found much of the evidence for religion.

Further Reading on Robert Boyle

Boyle's better-known writings are collected in Thomas Birch, ed., The Works of the Honourable Robert Boyle (5 vols., 1744; new ed., 6 vols., 1772), together with an account of his life which is the principal source of all subsequent biographies. Although not entirely satisfactory, the standard biography is Louis Trenchard More, The Life and Works of the Honorable Robert Boyle (1944). A briefer account, with extensive selections from his more important works, is Marie Boas Hall, Robert Boyle on Natural Philosophy (1965), while the significance of Boyle's chemical studies is discussed at length in her Robert Boyle and Seventeenth-Century Chemistry (1958). A case study of his work in pneumatics is contained in James Bryant Conant, ed., Harvard Case Histories in Experimental Science (2 vols., 1957).