The term solid waste related materials as used here refers to raw refuse such as is delivered to an incinerator or land-fill for disposal, to residues of the incineration process, and to refuse in various stages of composting. The assumption is made that major glass, ceramics and metal components have been removed prior to submission to the laboratory. The three basic operations to be applied to prepare them for detailed analysis are drying, grinding or pulverizing and mixing. The end products of these operations must be so thoroughly homogenized that portions weighing as little as 100-200 mg may be extracted for analysis with full confidence in their being uniform and representative so that any lack of precision or accuracy in the final results cannot be ascribed to the sample.