are heavier than the original metals—observations which long afterward served as one of the bases for modern chemistry. By completing the air pump, Sir Henry W. Ackland says, he "revolutionized the instrumentalities by which the atmosphere of the earth, the gases, many phenomena of life, and infinite chemical actions may be forever studied. It led, I doubt not, to the suggestion of rules proposed for the investigation of the Peak of Teneriffe—no small effort in the seventeenth century—and thus attempted to settle one physical problem which was set forth with great detail and precision by the Royal Society of the time." In his essays on this instrument, he "foresaw the far-reaching results through its agency of a more precise knowledge of the physical and the chemical properties of the atmosphere, . . . its relation to all organic life, and to meteorology in the widest cosmical sense. Henceforward he applied himself to experiments with this instrument, combined with his increasing power of chemical investigation, into almost all matter, above, upon, and within the globe; to vapors, to metals and stones of every kind. He studied respiration in the higher animals, investigated the effects of respired air on birds, on reptiles, on snails, and on plants, and the manner of death in each. Though experiments on living animals such as could then be performed were abhorrent to his tender soul, yet the knowledge of Nature was to him a religion; and he had to pierce through the secrets of life, the cause of disease, of suffering, and of death by every means that his ingenuity could devise."
When the Royal Society was incorporated, in 1663, Boyle was named a member of the Council. He was elected president of the society in 1689, but declined to serve in the office on account of his scruples against taking the oath. He was at one time interested in alchemy, and carried on experiments on the transmutation of metals. In the interest of this business he secured the repeal of the statute against multiplying gold and silver.
The religious side of Boyle's character was as prominent as the scientific side. Some experiences that happened to him in early youth gave a tinge of melancholy to his disposition; and he was moved by the reflections to which he was led by this trait to give himself for a considerable time wholly to an inquiry into the principles and the evidences of Christianity. Vital and sincere as was his faith, he was occasionally troubled with doubts, which he spoke of as being to the soul like toothache to the body, not mortal, but very inconvenient. The works of apologetics current in his time did not satisfy his mind, and he went to the original sources, studying Hebrew and the Oriental languages, and calling in the aid of the best theological scholars contemporary with him. The result of this inquiry was a conviction, the intensity of which was manifested by a great activity in religious discussion and reli-
