Mustard-seed oil

The white or yellow seed affords 36 per cent. of oil, and the black seed 18 per cent. The oil concretes when cooled a little below 32° F. Nut oil , is at first greenish coloured, but becomes pale yellow by time. It congeals at the same low temperature as linseed oil, into a white ma , and has a more drying quality than it. Oil of olives , is sometimes of a greenish and at others of a pale yellow colour. A few degrees above 32° F. it begins to deposit some white granules of stearine, especially if the oil have been originally expre ed with heat. At 22° it deposits 28 per cent. of its weight in stearine, which is fusible again at 68°, and affords 72 per cent. of oleine. According to Kerwych, oleine of singular beauty may be obtained by mixing 2 parts of olive oil with 1 part of caustic soda lye, and macerating the mixture for 24 hours with frequent agitation. Weak alcohol must then be poured into it, to di olve the stearine soap, whereby the oleine, which remains meanwhile unsaponified, is separated, and floats on the surface of the liquid. This being drawn off, a fresh quantity of spirits is to be poured in, till the separation of all the oleine be completed. It has a slightly yellowish tint, which may be removed by means of a little animal charcoal mixed with it in a warm place for 24 hours. By subsequent nitration, the oleine is obtained limpid and colourle , of such quality that it does not thicken with the greatest cold, nor does it affect either iron or copper instruments immersed in it. There are three kinds of olive oil in the market. The best, called virgin salad oil, is obtained by a gentle pre ure in the cold; the more common sort is procured by stronger pre ure, aided with the heat of boiling water; and thirdly, an inferior kind, by boiling the olive residuum or marc , with water, whereby a good deal of mucilaginous oil rises and floats on the surface. The latter serves chiefly for making soaps. A still worse oil is got by allowing the ma of bruised olives to ferment before subjecting it to pre ure. Oil of olives is refined for the watchmakers by the following simple proce . Into a bottle or phial containing it, a slip of sheet lead is immersed, and the bottle is placed at a window, where it may receive the rays of the sun. The oil by degrees gets covered with a curdy ma , which after some time settles to the bottom, while itself becomes limpid and colourle . As soon as the lead ceases to separate any more of that white substance, the oil is decanted off into another phial for use.