AMORPHISM (from a privative, and μορφή, form), a term used in chemistry and mineralogy to denote the absence of regular structure in a body. Glass, resin, coal, albuminous substances, &c., are amorphous, exhibiting uniformity of properties in every direction: they have no planes of cleavage, as crystals have; they conduct heat equally in all directions; and they do not show double refraction unless in a constrained state. Amorphism is not peculiar to one kind of substances, for the same molecules may exist either in the amorphous or the crystalline state. Thus charcoal or lamp-black is the amorphous form of the diamond; sulphur and phosphorus, when slowly cooled, assume a crystalline arrangement, but when rapidly cooled are perfectly homogeneous—the suddenness of transition from the liquid or fused state giving no time for definite arrangement of particles.