MINERALOGY, that science which teaches us the properties of mineral bodies, and by which we learn how to characterize, distinguish, and class them into a proper order. Mineralogy seems to have been in a manner coeval with the world. Precious stones of various kinds appear to have been well known among the Jews and Egyptians in the time of Moses ; and even the most rude and bar barous nations. appear to have had some knowledge of the ores of different metals. As the science iy nearly allied to chemis try, it is probable that the improvements, both in chemistry and mineralogy, have nearly kept pace with each other ; and in deed it is but of late, since the principles of chemistry were well understood, that mineralogy has been advanced to any de gree of perfection The best way of studying mineralogy, therefore, is by ap plying chemistry to it ; and not content. ing ourselves merely with inspecting the outsides of bodies, but decomposing them according to the rules of chemis try. This method has been 'brought to the greatest perfection by M. Pott of Ber lin, and after him by Mr. Cronstedt of Sweden. To obtain this end, chemical experiments in the large way are, with out doubt, necessary ; but as great tracts of the mineral kingdom have been ex amined in this manner by different wri ters, the curious mineralogist need not repeat those experiments in their whole extent An easy way may be adopted, which even for the most part is sufficient, and the processes of which, though made in miniature, are as scientifical as the common manner of proceeding in the laboratories, since it imitates that, and is also founded on the same principles. This method consists in making the ex periments upon a piece of charcoal, with the concentrated flame of a candle direct ed through a blow-pipe. The heat oc casioned by this is very intense, more especially if a stream of oxygen gas be thrown upon the subject under exami nation ; and the different mineral bodies may thus be burnt, calcined, melted, and scorified, &c. as well as in any great fur nace. When earths or stones are to be
tried, it is improper to begin immediately with the blowpipe : some preliminary experiments ought to be made, by which those in the fire may afterwards be di rected. For instance, a atone is not al ways homogeneous, or of the same kind throughout, although it may appear to the eye to be so. A magnifying glass is therefore necessary to discover the hete rogeneous particles, if there be any ; and these ought to be separated, and every part tried by itself, that the effects of two different things, examined together, may not be attributed to one alone. This might happen with some of the finer mice, which are now and then crewel mixed with small particles of quartz, scarcely to be perceived by the eye. The trapp is also sometimes mixed with very fine particles of feltspar, or of calcareous spar, &c. After this experiment, the hardness of the stone in question must be tried with steel. The flint and garnets are com monly known to strike fire with steel ; but there are also other stones, which though very seldom, are found so hard as likewise to strike fire. There is a kind of trapp of that hardness, in which no particles of felt spar are to be seen. Coloured glasses resemble true gems ; but as they are very soft in proportion to these, they are easily discovered by means of the file. The common quartz. crystals are harder than coloured glasses, but softer than the gems. The loadstone discovers the presence of iron, when it is not mixed in too small a quantity in the stone, and often before the stone is roast. ed. Some kinds of hematites, and par ticularly the cerulean, greatly resemble some other iron ores ; but this distin guishes itself from them by a red colour when pounded, the others giving a black. ish powder, and so forth.
In a work of this magnitude we cannot enter much at large into historical de. tails ; it may, however, be proper to no tice in brief the principal different sys tems that have been given to the world.