In European countries, Austria is particularly rich in graphite; and very large deposits of this mineral are found in Bohemia. Considerable deposits also occur in Bavaria, where they have long been worked. English graphite is celebrated for its excellent quality. All these European deposits, however, are surpassed, both in extent and in the quality of their products, by those discovered in Siberia, the largest being that producing the aforesaid Alibert graphite and situated, near the Chinese frontier, in eastern Siberia. At one time, America imported all her blacklead pencils from Europe, having, at that period, no known graphite deposits furnishing a suitable product. At present, however, deposits of this kind have been found in California, and there can be little doubt but that many others of this valuable mineral remain to be discovered in that enormous continent, the geological investigation of which is still far from being complete. The graphite of some deposits is so highly contaminated by extraneous minerals that it cannot be utilised, since the cost of purification would exceed the value of the product. On the other hand, the purer kinds, when suitably refined, yield a graphite that is fully adapted to all requirements. The refining process may be either chemical or mechanical, the choice of methods depending entirely on the character of the associated minerals. If these mainly consist of coarse, stony fragments, preference should be given to mechanical treatment; but if they are of such a character that they cannot be eliminated in this way, chemical methods must be employed. Sometimes the two systems are combined, by first subjecting the graphite to a rough mechanical purification, and then completing the operation with chemical reagents. The mechanical treatment consists in first removing as many of the impurities as possible by hand-picking, and grinding the remainder in edge-runner mills, along with water. The turbid liquid, containing the powdered graphite and extraneous minerals in suspension, is led through long launders, the sides of which are notched at intervals to allow the water to overflow into large pits. The graphite settling in the first of these pits contains numerous particles of the heavy associated minerals; but that remaining suspended in the water and carried on to the further pits constitutes the bulk. The water is left to clarify completely in the pits, and is then drawn off, the pasty residue being shaped into prisms, which are compressed under heavy pressure, to increase their density, when partially dry.