a mineral body, partly or entirely composed of metallic substances, in the natural state in which it exists in the earth. Metallic substances are found, either native, that is, pure, and uncombined with other substances, or alloyed with other metals, or combined with oxygen, or sulphur, or with acids; and thus it appears, that metals exist in ores, in four different states. 1. In the metallic state, when they are either pure, or combined with each other, as in the state of alloy. 2. In the state of an oxide. 3. Combined with sulphur in the state of sulphuret. And, 4. with acids, forming salts. For the particular description of ores, see MINERALOGY; and for the mode of their distribution in the earth, see GEOLOGY.

But ores are rarely found exactly in the state of combination now mentioned. It seldom indeed happens, that they are not mixed with various earthy minerals. As all metals are extracted from ores, it is of great importance to be acquainted, in the first place, with the materials of which they are composed, as they are obtained from the earth, with the view of ascertaining the nature and proportions of the various ingredients which enter into the composition; and in the second place, to know the simplest and easiest processes by which the metals may be separated, for the purposes of economy and manufactures. Hence, in the treatment of ores, two objects are in view. The first is their analysis, which is the province of the chemical philosopher; and the second is their reduction in the large way, which is the business of the metallurgist. The most improved methods for accomplishing each of these objects, will be detailed in the following treatise.