In geologic laboratories the organic heavy liquids bromoform, methylene iodide, tetrabromoethane, and clerici compounds have been used for years in mineral separation processes. Because the volume of use of these compounds is low, insufficient data is available on their toxic properties. This report is an attempt to summarize the known data from published and industry sources. The physical properties, hazards of handling,proper storage facilities, and adequate protective Clothing are discussed for each compound as well as for their common and less-common solvents. Toxicity data for these materials is listed along with exposure symptoms and suggested first aid treatments. Safety for the worker is emphasized. Three reclamation methods which recover the solvent used as a dilutant and purify the heavy liquid are discussed and illustrated. These include: the water cascade, re fluxing-distillation-condensation, and flash evaporation methods. Various techniques for restoration and stabilization of these heavy liquids are also included.