The name of black lead has very improperly been given to this substance from its appearance only, as it has no alliance whatever with lead. It is usually found in kidney─shaped lumps of various size, and occurs in several countries of Europe, but no where of such excellent quality as in Borrowdale, Cumberland, where it has the name of _wadd_. The vein of black lead lies between strata of slate, and is from eight to nine feet thick. This mine is not opened more than once every three or four years, the quantity thus obtained being found fully sufficient for the demand. The only other mine of black lead in Britain is in Ayrshire, Scotland. Artists in water─colours, if deprived of this mineral, would find great difficulty in making their sketches; as the marks that are erroneously made with it are more easily expunged than those of almost any other substance. Hundreds of thousands of pencils are every year formed of black lead. For this purpose the mineral is sawed into slender square pieces. These are fixed into grooves, of the same shape, cut in cedar, or some other soft wood; another piece of wood is then glued upon this, and the whole is worked into a circular form. The finer kinds of black lead are prepared for use by being boiled in oil before they are cut. The coarser kinds, and the refuse of the sawings, are melted with sulphur, and then cast into coarser pencils for carpenters. These may, in general, be easily distinguished by their sulphureous smell. The pencils that are manufactured in England are more esteemed on the Continent than any others. The powder produced in the sawing of pencils is employed for numerous purposes. It is used for giving a bright gloss to cast─iron grates and stoves, and defending them from rust, and from the action of fire. It may also be advantageously applied to the inner surface of wooden screws, to packing presses, the axles of various sorts of machines, to slides, and other wood work, which are subject to friction. In this respect it is far superior either to grease or soap. The makers of razor─strops occasionally employ black lead in the composition which they spread upon leather for the sharpening of razors; and, on the Continent, it is sometimes used for blackening the hair. A coarser kind of black lead is used for making the vessels that are used by chemists, called crucibles. RESIN FAMILY. 224. _AMBER is a substance usually of golden yellow colour, semi─transparent, and of shining and somewhat resinous lustre. It is occasionally seen of yellowish white colour, and nearly opaque._