vi advertisement. species I have endeavoured to bring into their proper places, and, by curtailing the descriptions of mere varie ties, have succeeded, although with the addition of one hundred and fifty minerals and about sixty figures, in not greatly increasing the size of the volume. With the in troductory portion of the book the same liberties have not been taken as with the descriptive, excepting only the chemical part; for the improved appearance of which, I am indebted to the able pen of a recently lamented and highly talented friend, whose name must long stand pre eminent among British chemists. In the descriptive part of the treatise considerable extracts have been made from my own Manual of Mineralogy (Edinburgh, 1833), which I trust will not be unacceptable; and for the most recent discoveries in the science, I have drawn from the works of Neckeu, Beudant, and Bose, as well as from the various scientific journals. In conclusion, I have only to express a wish that cir cumstances had of late afforded me better opportunities of doing greater justice to the work of Mr Phillips. It is sufficiently difficult to explain one’s own ideas on such a subject with perspicuity; but it must be allowed to be no easy task to engraft them on the work of another. If, however, I have succeeded in accommodating this origi nal British Treatise to the rapidly advancing state of mi- ncralogical science, and retaining the name of “ Phillips” in its former prominent position, I shall be fully repaid for the difficulties of my labour as an Editor. ROBERT ALLAN. lulinlurgh, March 1837.