The albuminous kernel of the walnut affords some 50 per cent. of oil. It is said that it furnishes one-third of all the oil made in France; it is extensively prepared in the central and southern departments, notably Charente, Charente-Inférieure, and Dordogne, where it is commonly met with in barrels of 50 _kilo_. In both Spain and Italy, outside the olive-region, walnut-oil is largely expressed. It is of considerable importance in the hill districts of India, but is seldom seen in the plains. Cashmere and Circassia also include it among their industrial products. The oil should not be extracted from the nuts until 2-3 months after they have been gathered. This delay is absolutely necessary to secure an abundant yield, as the fresh kernel contains only a sort of emulsive milk, and the oil continues to form after the harvest has taken place; if too long a period elapse, the oil will be less sweet, and perhaps even rancid. The kernels are carefully freed from shell and skin, and crushed into a paste, which is put into bags and submitted to a press; the first oil which escapes is termed “virgin,” and is reserved for feeding purposes. The cake is then rubbed down in boiling water, and pressed anew; the second oil, called “fire-drawn,” is applied to industrial uses. The exhausted cake forms good cattle-food. The virgin oil, recently extracted, is fluid, almost colourless, with a feeble odour, and not disagreeable flavour. Its sp. gr. is 0·926 at 59° F., and 0·871 at 201° F.; it thickens to a butter-like consistence at 5° F., and solidifies to a white mass at-17½° F. In the fresh state, it is largely used in Nassau, Switzerland, and other countries, as a substitute for olive-oil in salads, &c., but is scarcely to be considered as a first-class alimentary oil. The fire-drawn oil is greenish, caustic, and siccative, surpassing linseed-oil in the last respect and exhibiting the property more strongly as it becomes more rancid. On this account it is preferred by many artists before all other oils.