BOYLE. communicated to Mr. Hooke some observations on an artificial substance that shines without any preceding illustration, which were published by that gentleman in his “ Lectiones Cutler·anæ." And at the latter end of this year, as a proof of the high estimation in which he was held by Sir Isaac Newton, we may mention that that celebrated philosopher wrote him a very curious letter, in which he laid before him his sentiments upon that ethereal medium which he afterwards proposed in his Optics, as 169 the mechanical cause of gravitation Deeply impressed with a just sense of his great worth, and of the services he had rendered to science during the whole of his life, on the 30th of November this year, the Royal Society made choice of him för their president. This honour he, however, declined in a letter addressed to his friend Mr. Robert Hooke, being, as he says, even peculiarly tender in point of oaths. In 1680 he published " The Ærial Noetiluca; or, some new phenomena, and a process of factitious self-shining substance." Phosphorus, the substance here alluded to, was then of very recent discovery. The first inventor of it was Brandt, a citizen of Hamburgh, who imparted his process to one Kraaft; by whose persuasion he kept it a profound secret. In 1679 Kraaft brought a piece of it to England to shew to the king and queen, which having been seen by Mr. Boyle, he actually, in the following year, succeeded in making a small quantity, which he presented to the Royal Society, taking a receipl for it. The process was also discovered about the same time by Kunckel, another citizen of Hamburgh. It would not, however, have been necessary to be thus particular, had not Stahl, in a small work, entitled "Three hundred Experiments," stated that Kraaft informed him that he communicated the process to Mr. Boyle; a circumstance which we mast conceive to be entirely destitute of truth, when we con- sider the unimpeached veracity of Mr. Boyle, who would never have published to the world as his own discovery, a
