Fluid extract is a type of fluid-solid extraction, that usually employs Soxhlet Apparatus to extract certain compound with known solubility in a solvent. Some applications include extracting lipids from a plant (solid) using ethanol (liquid). In recent years this has expanded to include specialized extraction methodologies and equipment of a proprietary nature to ratio-intact extract multiple groups of compounds with discovered solubility in a solvent. This expansion has led to many successful applications such as extracting polysaccharides, resins and organic acids from a plant (solid) using glycerol (liquid). Fluid extracts are always permanent. They are concentrated.