EXTRACT (from

See also:

• LAT

Lat. extrahere, to draw out)  , in pharmacy, the name given to preparations formed by evaporating or concentrating solutions of active principles; tinctures are solutions which have not been subjected to any evaporation . " Liquid extracts " are those of a syrupy consistency, and are generally prepared by treating the drug with the solvent (water, alcohol, &c.) and concentrating the solution until it attains the desired consistency . " Ordinary extracts " are thick, tenacious and sometimes even dry preparations; they are obtained by evaporating solutions as obtained above, or the juices expressed from the plants . /Extraction, in chemical technology, is a process for separating one substance from another by taking advantage of the varying solubility of the components in some chosen solvent . The term " lixiviation " is used when water is the solvent . In laboratory practice all the common solvents are employed . With small quantities it may suffice to shake the substance with the solvent, the mixture being heated if necessary, filter and distil or otherwise remove the solvent from the distillate . For larger quantities continuous extraction is advisable . This may be carried out in many forms of apparatus; one of the most convenient is the Soxhlet extractor, in which the extract siphons into the flask containing the solvent, and so maintains the quantity of available solvent practically constant . Continuous extraction is generally the practice in technology . One of the most important applications is in the fat and gelatine industries .