That which is proper to anything; a peculiar quality of a thing; that which is inherent in a subject, or naturally essential to it; an attribute; as, sweetness is a property of sugar. "Property is correctly a synonym for peculiar quality; but it is frequently used as coextensive with quality in general." Note: In physical science, the properties of matter are distinguished to the three following classes: 1. Physical properties, or those which result from the relations of bodies to the physical agents, light, heat, electricity, gravitation, cohesion, adhesion, etc., and which are exhibited without a change in the composition or kind of matter acted on. They are color, luster, opacity, transparency, hardness, sonorousness, density, crystalline form, solubility, capability of osmotic diffusion, vaporization, boiling, fusion, etc. 2. Chemical properties, or those which are conditioned by affinity and composition; thus, combustion, explosion, and certain solutions are reactions occasioned by chemical properties. Chemical properties are identical when there is identity of composition and structure, and change according as the composition changes. 3. Organoleptic properties, or those forming a class which can not be included in either of the other two divisions. They manifest themselves in the contact of substances with the organs of taste, touch, and smell, or otherwise affect the living organism, as in the manner of medicines and poisons.