Robert Boyle. Portrait of the Irish chemist Robert Boyle (1627-91), who established chemistry as a separate science. His work stressed the need for experiment, precision and accurate observation. Boyle postulated that materials were made of a large number of 'elements' which could not be broken down into simpler chemicals. He formulated Boyle's law, which states that for a gas at a constant temperature the product of its pressure and volume is a constant. He devised analytical tests including the use of vegetable dyes as acid- base indicators and flame tests to detect metals. Boyle was a founder member of the Royal Society. This artwork is from an 1833/37 book.