erations touching the Usefulness of Experimental Philosophy. He also published, in 1663, an important volume of Experiments and Considerations upon Colors, with Observations on a Diamond that Shines in the Dark. Other scientific works are, New Experiments and Observations upon Cold, 1665; Origin of Forms and Qualities according to the Corpuscular Philosophy, 1666; Tracts about the Cosmical Qualities of Things, the Temperature of the Subterraneous Regions, and the Bottom of the Sea, 1669; Origin and Virtues of Gems, 1672; Essays on the Subtilty and Determinate Nature of Effluvia, 1673; tracts on the Saltness of the Sea, the Moisture of the Air, the Natural and Preternatural State of Bodies, Cold, Hidden Qualities of the Air, Celestial Magnates, Hobbes's Problem of a Vacuum, and the Cause of Attraction and Suction, 1674; Experiments and Notes about the Mechanical Origin or Production of Particular Qualities, including a Discourse on Electricity, 1676; the Aërial Noctiluca, or some New Phenomena, and a Process of a Factitious Self-shining Substance, 1680; New Experiments and Notes upon the Icy Noctiluca, to which is added a Chemical Paradox; Memoirs for the History of Human Blood, 1684; Short Memoirs for the Experimental History of Mineral Waters, 1685; Medicina Hydrostatica, 1690; Experimenta et Observationes Physicæ, 1691; and, published after his death, the General History of the Air Designed and Begun; an account of his making the phosphorus, September 30, 1680; and Medicinal Experiments. Most of the volumes of his works, with many manuscripts, exist in the library of the Royal Society. The works were collected in five folio volumes in 1744; a more complete edition, in six large quarto volumes, with a life by the editor, Dr. Birch, published in 1772, contains most of his scientific writings, several theological treatises, and numerous letters from him and to him.