Graphite, or black lead, is a mineral containing not more than five per cent of impurities, and is generally supposed to have originated as did mineral coal, and to represent a still more advanced stage of development. It occurs in various localities both in the vicinity of coal measures and far removed from them. The chief part of the world's supply comes from Ceylon, though Germany and the United States produce quantities of graphite of excellent quality. In the Laurentian rocks of Canada, and of course with as ancient origin, extensive deposits are found. This presence of graphite in strata in which as yet no certain traces of organic life have been found has led some to believe that this form of carbon mineral may have another than organic origin. Various uses are served by graphite. The chemist finds it of great value in making his crucibles; the engineer uses it, finely powdered, as a lubricant; the housekeeper polishes stoves with it; the electrician uses it in his arc lights; all civilized nations use it in the lead of lead pencils. The stem, _grapho_ (to write), on which so many of our words, as geography, telegraph, graphophone, etc., are formed, suggests also the origin of the name, graphite. The finest quality lead pencils are those made from graphite occurring in a state sufficiently pure to allow the cutting and grinding of pieces to the size needed. In the case of the medium and poorer grade pencils, the graphite has first been finely powdered and then pressed into the requisite shape and size. The purest form of carbon found in nature is the diamond. The rare occurrence of diamonds indicates that the essential conditions in nature for causing the transformation of some less pure form of carbon into diamond are seldom present. While diamonds have actually been produced in the laboratory by far-seeing and indefatigable chemists, yet the cost of such products is so great as to preclude the possibility of the most precious of gems becoming at all common. The diamond is the hardest of all known substances, and will scratch any other mineral across which it may be drawn. Three localities have successively furnished the main part of the world's stock of diamonds. A century and a half ago, practically all the diamonds came from India, where at one time 60,000 persons were employed in diamond digging. Toward the middle of the eighteenth century, when the diamondiferous districts of India were becoming exhausted, the discovery of the precious gem in Brazilian deposits was made. At present, the supply of diamonds from Brazil has much diminished, and the diamond fields of South Africa, where is located the famous Kimberley mine, produce the larger part of the world's output of diamonds.