This document discusses different types of solids found in environmental samples and their measurement. It defines total solids, total suspended solids, total dissolved solids, volatile solids, and fixed solids. Key points include: total solids are all solids in a sample, total suspended solids are filterable, total dissolved solids pass through a filter, and volatile solids are lost during ignition while fixed solids remain. The document provides methods for measuring total suspended solids, including filtration, drying, ignition, and calculations. It also discusses the environmental significance of different solids measurements.