object portion of mixture Examples: saline solution, a suspension of dust particles in air, milk. Typically, the grains of the object aggregates are molecules (as in a solution of salt in water), but a mate- rial entity made of gravel mixed in a heap of soil also meets the definition, where the grains are individual rocks (gravel) and particles of soil. William Hogan William Hogan a material entity that contains two or more scattered object aggregates as its only parts, where the grains of each object aggregate are of different types and evenly distributed throughout, such that any two parts of the entity, each of which is spatially contiguous and of the same size, contain nearly equal numbers of grains of the aggregates