Scientists & Mathematicians : Robert Boyle

Irish natural philosopher and one of the founders of modern chemistry. He is best remembered for the law named after him, which states that, at a constant temperature, the volume of a given mass of gas is inversely proportional to the pressure upon it. He was instrumental in the founding of the Royal Society and a pioneer in the use of experiment and the scientific method.

Boyle was born on 25 January 1627 in Lismore Castle, County Waterford, the fourteenth child and seventh son of the Earl of Cork. He learned to speak French and Latin as a child and was sent to Eton College at the early age of eight. In 1641 he visited Italy, returning to England in 1644. He joined a group known as the Invisible College, whose aim was to cultivate the ‘new philosophy’ and which met at Gresham College, London, and in Oxford, where Boyle went to live in 1654. The Invisible College became, under a charter granted by Charles II in 1663, the Royal Society of London for Improving Natural Knowledge, and Boyle was a member of its first council. (He was elected president of the Royal Society in 1680, but declined the office.) He moved to London in 1668 where he lived with his sister for the rest of his life. He died there on 30 December 1691.

Boyle's most active research was carried out while he lived in Oxford. By careful experiments he established the law that now bears his name. He determined the density of air and pointed out that bodies alter in weight according to the varying buoyancy of the atmosphere. He compared the lower strata of the air to a number of sponges or small springs that are compressed by the weight of the layers of air above them. In 1660 these findings were published in a book The Spring of Air, which also gave us the word ‘elastic’ in its present meaning(Boyle's law is not stated clearly until the revised edition was published in 1662).

A year later Boyle published The Sceptical Chymist, in which he criticized previous researchers for thinking that salt, sulphur, and mercury were the ‘true principles of things’. He advanced towards the view that matter is ultimately composed of ‘corpuscles’ of various sorts and sizes, capable of arranging themselves into groups, and that each group constitutes a chemical substance. He successfully distinguished between mixtures and compounds and showed that a compound can have very different qualities from those of its constituents.

Also in about 1660 Boyle studied the chemistry of combustion, with the assistance of his pupil Robert Hooke. They proved, using an air pump, that neither charcoal nor sulphur burns when strongly heated in a vessel exhausted of air, although each inflames as soon as air is re-admitted. Boyle then found that a mixture of either substance with saltpetre (potassium nitrate) catches fire even when heated in a vacuum and concluded that combustion must depend on something common to both air and saltpetre. Further experiments involved burning a range of combustible substances in a bell jar of air enclosed over water. But it was left to Joseph Priestley in 1774 to discover the component of air that vigorously supports combustion, which three years later Antoine Lavoisier named ‘oxygen’...