characters, by all of whom he was beloved and respected, from the vast fund of information he possessed, he employed his time in maturing his views and searching into the secrets of nature with unwearied zeal. In one of these experiments he discovered that mineral alkali is contained in zeolite. On boiling the gelatinous substance obtained from combining that fossil with muriatic acid he found that, after evaporation, the salt was formed. Dr Playfair thinks this to be the first instance of an alkali being discovered in a stony body. The experiments of M. Klaprath and Dr Kennedy have confirmed the conclusion, and led to others of the same kind. With a view of completing his Theory of the Earth, he made many journeys into different parts of England and Wales, and on visiting the salt mines of Cheshire, he made the curious observations of the concentric circles marked on the roofs of these mines, to which he has referred in his Theory, as affording a proof that the salt rock was not formed from mere aqueous deposition.
In 1777, Dr Mutton's first publication was given to the world in the shape of a pamphlet, on the "Nature, Quality, and Distinctions of Coal and Culm." This was occasioned by a question which the board of customs and privy council wished to have settled, in order to fix on the proportion of duty the one should bear with the other when carried coastwise. Dr Button's pamphlet was considered so ingenious and satisfactory, that an exemption of the small coal of Scotland from paying duty on such short voyages was the consequence. He took a lively interest in promoting the arts of his native country, and devoted much of his time and attention to the project of an internal navigation between the Firths of Forth and Clyde. He read several papers in the Philosophical Society, before its incorporation with the Royal Society, (none of which Mere then published, with the exception of one in the second volume of the Transactions of the Royal Society,) "on certain natural appearances of the ground on the hill of Arthur's Seat." His zeal for the support of science in Edinburgh induced him to come forward and communicate to the Royal Society a Sketch of a Theory of the Earth, the perfecting of which had occupied his constant attention for a period of thirty years, during which time he had never ceased to study the natural history of the globe, with a view of ascertaining all the changes that have taken place on its surface, and discovering the causes by which they have been produced; and from his great skill as a mineralogist, and having examined the great leading facts of geology with his own eyes, and carefully studied every learned work on the natural history of the earth, it must be acknowledged that few men could enter better prepared on so arduous a task. As this Theory is so well known, and has been the subject of so much controversy, our limits will not permit us to enter upon it here; we therefore refer our readers to the book itself.
Dr Kirwan of Dublin, and others, considered Dr Button's Theory both eccentric and paradoxical, and charged him with presumption in speculating on subjects to which the mere human understanding is incompetent to reach, while some gave a preference to the system of Berkeley, as more simple and philosophical; but notwithstanding all the attacks which the new doctrines of Hutton Mere subjected to, he had the proud satisfaction of being fortified in his opinions by many great and good men, who were bound to him by the closest ties of friendship. Dr Black, Mr Clerk of Eldin, and professor Playfair, as occasion required, were willing and ready to vindicate his hypothesis. But setting aside all these considerations, there existed in the work itself many faults, which contributed not a little to prevent Dr Hutton's system from making a due impression on the world. In the opinion of his greatest defender, professor Playfair, "It Mas proposed too briefly, and with too little detail of facts for a system which
