(FR., Huile de Pepins de " stones " or seeds of the common grape (Vitis vinifera), elsewhere described (see Beverages, p. 432; Fruit, p. 1027), have been utilized for their oil in Europe for more than a century. In S. France, it is computed that an average of 1 lb. of seeds is furnished by the grapes converted into 1 gal. of wine, so that the produc tion is considerable as a whole. The seeds of black grapes contain much more oil than those of white ones ; and those obtained from vines in full vigour are more oleaginous than those gathered at other periods. Generally speaking, the seeds of black grapes give 15-18 per cent. of oil ; of white ones, 10-14 per cent. In France, the vines of Roussillon, Aude, and Hdrault afford the most oil. It is probable that American, especially Californian, vines may yield more oil than French vines. The preparation of the oil from grape-seeds is largely carried on in S. France, and in those parts of Italy where vine-culture is common, and olive-culture is rare, notably Lombardy.
The seeds chosen for the purpose are separated as promptly as possible from the refuse result ing from the distillation of brandy (see p. 201) or the manufacture of verdigris (see p. 30); they are rendered perfectly clean, and most completely dried in the sun and air, and are then ground to a fine flour in ordinary mills, the fineness of the grinding having a direct inflnence on the yield of oil. Some manufacturers first subject the flour to a cold expression, and extract about 5 per cent. of oil, afterwards repeating the pressure with heat, and obtaining an additional 10-15 per cent. A more detailed operation sometimes adopted is as follows. The flour is moistened with a little water as fast as it emerges from the mill, and is then thrown into open boilers ; a hole is made in the middle of the flour by the hand, reaching to the bottom of the vessel, and into this some water is poured ; a slow fire is then kindled under the boiler, and the contents are unceasingly stirred, to thoroughly incorporate the water with the flour ; the fire is withdrawn as soon as the heat is greater than can be borne by the hand inserted in the mass, and the latter is placed in bags and immediately pressed.
The oil has a clear yellow colour when fresh, becoming brownish-yellow with age; it is inodorous, and of faint flavour. Its sp. gr. when new is 0.918; in a short time, it increases to 0.920 at 15° (59° F.). It solidifiea at 13° 16° F.); becomes viscid and rancid when exposed to the sir ; and saponifies readily, but gives a soap lacking hardness and density. It is said to con tain chiefly erneic acid, with some stearic and palmitic acids, combined as glycerides. The fresh oil is used in Italy fur culinary purposes, being considered superior to nut-oil, and but little inferior to olive-oil. It is valuable for illuminating, emitting a bright light quite free from smoke. It has been recommended as a lubricator, on account of its low congealing-point, hut its drying properties preclude its use in this direction.
Ground-nut- or Arachis-oil (FR., Huge d' Arachide,de Pistache de Terre; GER., Erdnuesb7). The ground-nut (see p.1357) is very widely cultivated for the sake of its oily seeds. In Java, the oil is extracted by drying the seeds in the sun, and then subjecting them to pressure. lu European mills, the nuts are first cleaned, then decorticated, and winnowed, by which the kernels are loft perfectly clean. These are crushed like any other oil-seed, and put into bags, which are intro duced into cold presses ; the expressed oil is refined by passing through filter-bags. The residual cake is ground very fine, and pressed under 3 tons to the inch, in the presence of steam-heat ; this affords a second quantity of oil, inferior in quality to the cold-pressed. The usual product is 1 gal. of oil from 1 bush, of nuts by the cold process, besides the extra yield by the hot-pressing. In France, where the oil is most largely prepared, 3 expressions are adopted, as with some sorts of gingelly the first gives about 18 per cent. of superfine oil, fit for alimentary purposes ; the second, after moisten ing with cold water, affords 6 per cent. of a fine oil, suitable for lighting and for woollen-dressing; the third, after treating with hot water, yields 6 per cent. of rabat, or oil applicable only to soap making. In India, the total mean yield is 37 per cent. at Pondicherry, and 43 in Madras. The cold pressed oil is almost colourless, of agreeable faint odour, and blend olive-like flavour. The best has a sp. gr. of about or 0.9163 at 15° F.); it becomes turbid at 3° (37° F.), concretes at 3° F.), and hardens at 7°(19i. F.). By exposure, it changes very slowly, but thickens with time, and assumes a rancid odour and flavour. As an illuminating-oil, it has feeble power, and its chief industrial uses are for soap-making and lubricating, particularly the former. Locally, it is employed for cooking and burning, and as a general substitute for olive-oil. Indeed, very large quantities are readily passed off as olive-oil in European markets. As a rule, the seeds are exported in a raw state to such centres as London, Marseilles, Bordeaux, Nantes, Dunkirk, Hamburg, and Berlin, where they are crushed, and the oil passes into general commerce without maintaining its identity. Thus statistics concerning it are meagre. Pondicherry exported 99,330 veltes (of 1.64 gal.) of the oil in 1860 ; but the most extensive foreign trade iu the oil takes place with China. Thus Shanghai, in 1879, imported 1604 piculs (of 1331 lb.) from Chinese ports, and exported 81674 penis to Chinese ports, and 840i to foreign countries; in 1878, the exports to foreign countries were 786 piculs. The lowest estimate of the annual export from Pakhoi is 90,000 piculs. Hankow, in 1879, imported 651 piculs, value 1497/., of native oil. The nuts from the Galan district (W. Africa) are most esteemed for their yield of oil and the thinness of their shells.