ABSTRACT
Looking up substance in a dictionary may yield the following definitions relevant to the MFA field: the physical matter of which a thing consists; material;2 matter of particular or definite chemical constitution;3 or: matter; material of specified, especially complex, constitution.4 For material one may find: of matter; of substance;2
the elements, constituents, or substances of which something is composed or can be made;3 and the substance or substances out of which a thing is or may be constructed.4 All of these definitions seem convincing, but they are not precise enough for our purposes. As a matter of fact, it would be difficult to decide based on the above definitions whether “wood” should be addressed as a “substance” or “material.” In everyday language both terms are used more or less synonymously. Therefore, MFA relies on the term substance as defined by chemical science. A substance is any (chemical) element or compound composed of uniform units. All substances are characterized by a unique and identical constitution and are thus homogeneous.5 Using this definition makes clear that “wood” is not a substance. It is composed of many different substances such as cellulose, hydrogen, oxygen, and many others. Thus, a substance consists of identical units only. If these units are atoms, one speaks about a (chemical) element such as carbon (C), nitrogen (N), or cadmium (Cd). In cases where the units represent molecules such as carbon dioxide (CO2), ammonium (NH3), or cadmium chloride (CdCl2) they are designated as
(chemical) compounds. In MFA, chemical elements and compounds both are correctly addressed as substances.
