. A treatise on pharmacy for students and pharmacists. if in thiu layers, form varnish-like masses, whereasthe non-drying oils remain fluid and become rancid. Although fats are found in various parts of plants, those intendedfor use are collected exclusively from the fruit and seed, and areobtained either by expression or by extraction with some suitablesolvent; the former process yields somewhat lower results, but ispreferred because less troublesome and productive in many cases of asuperior article. In Fig. 195 is shown an hydraulic press extensivelyused for the expression of mustard, cotton
. A treatise on pharmacy for students and pharmacists. if in thiu layers, form varnish-like masses, whereasthe non-drying oils remain fluid and become rancid. Although fats are found in various parts of plants, those intendedfor use are collected exclusively from the fruit and seed, and areobtained either by expression or by extraction with some suitablesolvent; the former process yields somewhat lower results, but ispreferred because less troublesome and productive in many cases of asuperior article. In Fig. 195 is shown an hydraulic press extensivelyused for the expression of mustard, cotton seed, and linseed crushed material, after being heated somewhat, is placed in sacks 188 GENERAL PHARMACY or press-cloths between the series of plates, and pressure appliedfrom below, the oil being collected in the large box or trough, andfrom there delivered into the receiving vessel. The residue fromcertain seed expressions is used, under the name of oil-cake, as foodfor cattle and hogs or for fertilizing purposes. Cold expression Fig. 19c. Steam press for fixed oils. yields a finer oil than when heat is employed, although slight warm-ing is generally resorted to so as to render the oil more fluid in theseed and thus insure a better flow. Expressed oils are always moreor less contaminated with impurities, such as mucilaginous and albu-minous matter, which are removed by allowing the oil to settle inlarge tanks and drawing off the clear liquid. Frequently filtrationis employed for improving the quality of the oil, felt or flannel bags CLASSIFICATION OF NATURAL PRODUCTS. 189 being best adapted for this purpose. When purification of fixed oilsbecomes necessary they are treated either with sulphuric acid, causticalkalies, zinc chloride, tannin, or alkali carbonates, and subsequentlywashed with hot water, after which they are carefully decanted. The extraction of fixed oils is conducted in specially constructedextractors, frequently so arranged that the solvent is made to
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Keywords: ., bookcentury1800, bookdecade189, booksubjectpharmacy, bookyear1895
