sugar-cane, and the bamboo,--a silicate (an actual flint) is taken up by the roots and stored away in the stalks as a stiffener. The rough, sharp edge of a blade of grass sometimes makes an ugly cut on one's finger by means of the flint it contains. Silex is the chief ingredient in quartz rock, which is so widely diffused over the earth, and enters into the composition of most of the precious stones. The ruby, the emerald, the topaz, the amethyst, chalcedony, carnelian, jasper, agate, and garnet, and all the beautiful varieties of rock crystal, are mostly or entirely silex. Glass is a compound of silex and pearlash. One who is curious in such things may make glass out of a straw, by burning it and heating the ashes with a blowpipe. A little globule of pure glass will form as the ashes are consumed. The following curious instance, quoted by that interesting physiologist, Dr. Carpenter, shows the same effect upon a large scale. A melted mass of glassy substance was found on a meadow between Mannheim and Heidelberg, in Germany, after a thunder-storm. It was, at first, supposed to be a meteor; but, when chemically examined, it proved to consist of silex, combined with potash,--in the form in which it exists in grasses; and, upon further inquiry, it was ascertained that a stack of hay had stood upon the spot, of which nothing remained but the ashes, the whole having been ignited by the lightning. There is nothing in Nature more striking to the novice than the first suggestions of the various, and apparently contradictory, at least unexpected, positions in which the same mineral is found. Now carbon is one of the minerals whose exchanges are peculiarly interesting. Chemists say that the diamond is the only instance in Nature of pure carbon: it burns in oxygen under the influence of intense heat, and leaves no ashes. Next to this--strange gradation!--is charcoal, which comes within a very little of being a diamond. But just that little interval is apparently so great, that none but a chemist would suspect there was any relationship between them. Then come all those immense beds of coal which compose one of the geological strata of the earth's crust, a stratum that was formed before the appearance of the animated creation, when the earth was clothed with a gigantic forest, whose mighty trunks buried themselves with their fallen leaves, and became, in time, a continuous bed of carbonaceous stone.