As an article of modern utility, it is to be remarked that the Arabians dissolve asphalt in oil, and, with the mixture, smear their horse harness, to preserve it from the effects of weather, and the attacks of insects. In a state of solution it is applied, in several eastern countries, as a covering for timber and the bottoms of ships. It is occasionally used in the cleansing and healing of ulcers, and other sores. In France it is manufactured into a substance which is in considerable request for greasing the wheels of carriages. It is used by the makers of watch─dials, who mix it with lamp black, and oil of turpentine; but its chief use is as an ingredient in certain varnishes, and particularly in the varnish used by copper─plate engravers. It is frequently adulterated by a mixture with common pitch; but this is easily discovered by the smell. Besides the countries and places already mentioned, asphalt is found in several parts of America, in the island of Trinidad, in the province of Neufchatel, and many parts of the Continent of Europe. COAL FAMILY. 217. The component parts of coals are principally carbon or charcoal (48), and bitumen (216). Some kinds of coal are laminar, and others compact. They in general burn freely, with a bituminous odour, and leave a considerable residuum. This invaluable mineral is found in beds, or strata, frequently betwixt clay slate (257) and sandstone (267), and seldom betwixt those of limestone (140). It chiefly occurs in the northern hemisphere, particularly in countries which lie nearly in the same latitudes with Great Britain; in Siberia, Germany, Sweden, France, Canada, and Newfoundland; and in some of the northern parts of China. It is stated to be abundant in New Holland; but we have no distinct account of coal in the continent of Africa. No fewer than seventy different kinds of coals are brought to the London market, the value and prices of which greatly differ. Of these the coals called _Wall’s─end_, from the name of the pit, near Newcastle, whence they are obtained, usually bear the highest price. 218. _COMMON COAL, or PIT COAL, is of black colour, and has generally a slaty structure and foliated texture._ _When handled it stains the fingers; and when burnt it cakes more or less during combustion. Its component parts are usually charcoal (48) and bitumen (216), with a small portion of clay, and sometimes with pyrites, or sulphat of iron (236). What is called slaty coal contains a greater portion of clay than other kinds._