Encyclopædia Britannica, Ninth Edition/Poppy Oil

POPPY OIL is obtained by pressure from the minute seeds of the garden or opium poppy, Papaver somniferum (see Opium, vol. xvii. p. 787). The white-seeded and black-seeded varieties are both used for oil-pressing; but, when the production of oil is the principal object of the culture, the black seed is usually preferred. The qualities of the oil yielded by both varieties and the proportion they contain (from 50 to 60 per cent.) are the same. By cold pressure seeds of fine quality yield from 30 to 40 per cent. of virgin or white oil (huile blanche), a transparent limpid fluid with a slight yellowish tinge, bland and pleasant to taste, and with almost no perceptible smell. On second pressure with the aid of heat an additional 20 to 25 per cent. of inferior oil (huile de fabrique or huile russe) is obtained, reddish in colour, possessed of a biting taste, and a linseed-like smell. The oil belongs to the linoleic or drying series, having as its principal constituent linolein; and it possesses greater drying power than raw linseed oil. Its specific gravity at 15° C. is 0·925; it remains limpid at −15° C., but forms a thick white mass at −20° C., which does not again become fluid till the temperature rises to −2° C. Poppy oil is a valuable and much used medium for artistic oil painting. The fine qualities are largely used in the north of France (huile de œillette) and in Germany as a salad oil, and are less liable than olive oil to rancidity. The absence of taste and characteristic smell in poppy oil also leads to its being much used for adulterating olive oil. The inferior qualities are principally consumed in soap-making and varnish-making, and for burning in lamps. The oil is very extensively used in the valley of the Ganges and other opium regions for food and domestic purposes. By native methods in India about 30 per cent. of oil is extracted, and the remaining oleaginous cake is used as food by the poor. Ordinary poppy-oil cake is a valuable feeding material, rich in nitrogenous constituents, with an ash showing an unusually large proportion of phosphoric acid. The seed of the yellow horned poppy, Glaucium luteum, yields from 30 to 35 per cent. of an oil having the same drying and other properties as poppy oil; and from the Mexican poppy, Argemone mexicana, is obtained a non-drying purgative oil useful as a lubricant and for burning.