A man of integrity, modest, simple, and unassuming, Boyle was an assiduous and true student of science, and practically the whole of his life was given to its pursuit. His social position, his example, the purity of his private life, and the fame of his discoveries made his personal influence very considerable, to the great advantage of science in this country. His experimental work was of a high order. He introduced the air-pump into England, and his “pneumatical engine” enabled him to discover many of the fundamental properties of a gas, notably the relation of its volume to pressure. He also discovered the dependence of the boiling point of a liquid upon atmospheric pressure, explained the action of the syphon, the effect of the air on the vibration of a pendulum and on the propagation of sound, and made experiments on the nature of flame, and on the relation of air to combustion and respiration. In his _History of Fluidity_ he seeks to show that a body seems to be fluid by consisting of corpuscles touching one another only in some parts of their surfaces; whence, by reason of the numerous spaces between them, they easily glide along each other till they meet with some resisting body to whose internal surface they exquisitely accommodate themselves. He considers the requisites of fluidity to be chiefly these: The smallness of the component particles, their determinate figure, the vacant spaces between them, and the fact of their being agitated variously and apart by their own innate motion or by some thinner substance which tosses them about in its passage through them. His published works contain many well-authenticated chemical facts, which are commonly held to be the discovery of a later time. He prepared acetone by the distillation of the acetates of lead and lime; and he isolated methyl alcohol from the products of the destructive distillation of wood. He was one of the earliest to insist on the necessity of studying the forms of crystals. He saw in their formation proof that the internal motions, configuration, and position of the integral parts are all that is necessary to account for alterations and diversities in outward character. Some of the stock illustrations of our lecture-rooms were of his contrivance. Thus he illustrated the expansive power of freezing water by bursting a plugged gun-barrel filled with water by solidifying the water by means of a mixture of snow and salt—a freezing mixture which he first introduced.