Publishers Note: A hands-on practical guide to performing various operations in assaying and extracting, qualitative and quantitative analysis, refining, classifying, and concentrating precious metals, either from primary sources such as ore and black sand or from secondary sources such as scrap jewelry and old film. Intended for professionals, semi-professionals, or hobbyists with or without a background in chemistry; does not discuss the mathematical formulas for chemical reactions. No date is noted for the first edition. Annotation c. by Book News, Inc., Portland, Or.