INTRODUCTION. Mincralo- £ical chc- miftry. Oeconomi- cai mine- ralogy. us a pi&ure of the ftrufture and compofition of’ par ticular trafts, geognofie that of the whole globe. Minerakgical Chemiftry—makes us acquainted with the quantity and quality of the confticuent parts of minerals. Occonomica! Mineralogy—teaches us the different ufes of minerals. This excellent fubdivifion of the fcience, firft mark ed its true limits, and its vail extent, and pointed out a clear path for future minera,logift$. Notwithflanding the labours of thefe iwluftrioup obfervers, our knowledge of the internal ftrutture of the earth was Hill very li mited and coufufed. Although obfervation3 had been made in very diftant countries, and fimilar rocks difcovered in a variety of the moll widely diftant fituations, yet no fuccefsful attempt had been made to generalize thefe appearances, fo as to difcover the general ftru&ure of the earth, and the mode of its formation. Sauffure made the attempt, but neither hisinformafion nor ability feem to have been equal to this great talk. He was alfo unac quainted with many fafts which would have a (Tilted him, and his attention was too much occupied with particular and local ap pearances to effe£t what has been fince fo fully acconiplifhed by the coinprehenfive mind of Werner. This great geognoft, after many years of the moll arduous in- veftigations, conduced with an accuracy and acuteneis of which we have few examples, difcovered the manner in which the cruft of the earth is conftrudted. Having made this great difcovery, he, after deep reflection, and in conformity with the ftriiEteft rules of induction, drew mod interefling conelulions, as to the manner in which the folid mafs of the earth may have been form ed. It is that fplettdid fpecimen of inveftigation, the inoft per- fe£t in its kind ever prefented to the world, which I (hall give an account of in the volume of this work which treats of Gcog- noftc. C. As
