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in potteries and in the manufacture the East Indies. It is a very virulent poison.

of porcelain.

NINZIN: a root greatly esteemed in the East, bearing some resemblance to ginseng. It is collected on the mountains of Corea. The Chinese give it as a restorative cordial and provocative.

NITRE. See SALTPETRE. NONPAREIL: a small-sized type, on which small Bibles and common prayer-books are often printed. Also the name of a celebrated apple.

NOTES, PROMISSORY. Promissory notes are merely written promises to pay the sums therein written either specifically to a particular person, or generally to any person who may be the bearer of them, or sometimes to the order of a particular person, at the time specified; which, in bankers' notes, is usually on demand.

NUTMEG: the kernel of a large fruit not unlike the peach. The best nutmegs are brought from the East Indies in stone jars. The round nutmeg is preferred to that which is oblong. The fruit nowhere attains the same perfection as in the Moluccas.

NUX VOMICA: the fruit of a plant growing in various parts of

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OAKUM: old ropes untwisted and pulled out into loose hemp, in order to be used in caulking the seams, treenails and bends of a ship, for stopping leaks, &c.

OCHRE combinations of earths with the oxide of iron. Ochres are of various colors, as red, blue, yellow, brown, green, &c. They are found in abundance in different parts of North America, and the Indians are in the habit of smearing their faces with them. Ochres are of extensive use as colors, not only in oil but in water painting.

OCTAVO signifies a sheet of paper folded into eight leaves.

OFFING in the sea language, that part of the sea a good distance from shore, where there is deep water, and no need of a pilot to conduct the ship. Thus if a ship from shore is seen sailing out to seaward, they say she stands for the offing; and if a ship, having the shore near her, has another a good way without her, or towards the sea, they say that ship is in the offing.

OIL. The term OIL is applied to designate a number of unctuous liquors, which, when dropped upon paper, sink into it, and make it seem semi-transparent, or give it what is called a greasy stain. These bodies are very numerous, and have been in use from time immemorial. Chemists have divided them into two classes; namely, volatile and fixed oils.

Volatile oils, called also essential oils, are liquid-often almost as liquid as water-very combustible, soluble in alcohol, and they evaporate without leaving any stain on paper. By this last test, it is easy to discover whether they have been adulterated with any of the fixed oils. Let a drop of the volatile oil fall on a sheet of writing paper, and then apply a gentle heat to it; if it evaporates without leaving stain upon the paper, the oil is pure; but if it leaves a stain, it has been contaminated.

any

Volatile oils are almost all obtained from vegetables, and they exist in every part of plants—the root, the bark, the wood, the leaves, the flower, and even the fruit. When these oils are contained in great abundance in plants, they are sometimes obtained by simole

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expression. This is the case with oil of oranges, of lemons, and bergamot; but in general they can only be obtained by distillation. The part of the plant containing the oil is put into a still with a quantity of water, which is distilled off by the application of a moderate heat. The oil comes along with the water, and swims upon its surface in the receiver. By this process are obtained the oil of peppermint, thyme, lavender, and a great many others, which are prepared and employed by the perfumer; others are procured by the distillation of resinous bodies. This is the case in particular with oil of turpentine, which is obtained by distilling a kind of resinous juice, that exudes from the pine, the juniper, and other trees.

The color of the volatile oils is as various as their other properties. A great number are limpid and colorless, as oils of turpentine, lavender, aniseed; some are yellow, as spike, bergamot; some are blue, as camomile, motherwort; others green, as pepper, wormwood, cajeput, &c.; others, though at first colorless, become yellow or brown by age, as cloves, cinnamon, sassafras.

Fixed oils are distinguished by an unctuous feel and a mild taste; they are liquid, or easily become so when exposed to a gentle heat; very combustible; insoluble in water, and nearly so in alcohol; and they leave a greasy stain upon paper.

These oils, which are called fat or expressed oils, are numerous, and are obtained partly from animals and partly from vegetables, by simple expression. As instances, may be mentioned whale oil or train oil, obtained from the blubber of the whale and from cod; olive oil, obtained from the fruit of the olive; linseed oil and almond oil, obtained from linseed and almond kernels. Fixed oils may also be extracted from poppy seeds, hemp seeds, beech mast, and many other vegetable substances.

Fixed oil, when in the state of vapor, takes fire on the approach of an ignited body, and burns with a yellowish white flame. It is upon this principle that candles and lamps burn. The tallow or oil is first converted into a state of vapor in the wick; it then takes fire, and supplies a sufficient quantity of heat to convert more oil into vapor; and this process goes on while any oil remains. The wick is neces

sary to present a sufficiently small quantity of oil at once for the heat to act upon.

The drying oils are used as the vehicle of paints and varnishes. Linseed, nut, poppy and hemp-seed oils belong to this class. These oils in their natural state possess the property of drying oils but imperfectly. To prepare them for the use of the painter and varnish maker, they are boiled for some time in an iron pot, and sometimes burnt, till they become viscid. When they burn for some time, their unctuous quality is much more completely destroyed than by any method that has been practised. Hence it is followed fiequently in preparing the drying oils for varnishes, and always for printers' ink, which requires to be as free as possible from all unctuosity.

Nut oil has been found preferable to all other oils for printers' ink; though the dark color which it acquires during boiling renders it not so proper for red ink as for black. Linseed oil is considered as next after nut oil in this respect. Other oils cannot be employed, because they cannot be sufficiently freed from their unctuosity. Ink made with them would be apt to come off

and smear the paper while in the hands of the book-binder, or even to spread beyond the mark of the types, and stain the paper yellow. OLIBANUM: a gum resin, the produce of a large tree growing in Arabia and India. It is imported in chests. The best is of a pink color, brittle, and adhesive, when warm; when burnt, the odor is very agreeable; its taste is bitterish, and somewhat pungent and aromatic; it flames for a long time, with a steady clear light, which is not readily extinguished.

OLIVES: a fruit which yields a large quantity of oil, the produce of the olea, olive tree. Olives intended for preservation are gathered before they are ripe. In pickling, the object is to remove their bitterness, and to preserve them green by impregnating them with a brine of aromatized sea salt; for this purpose various methods are employed. The wood of the olive tree is beautifully veined, and has an agreeable smell. It is in great esteem with cabinet-makers, on account of the fine polish of which it is susceptible. The olive is much cultivated in the south of France, Spain, Italy and Portugal. The Lucca olives, which are smaller

than the others, have the weakest taste; the Spanish, or larger, the strongest; the Provence, which are of middling size, are generally the most esteemed, though many prefer the Spanish.

OLIVE OIL. The olive tree is principally cultivated for the sake of its oil. This is an insipid, inodorous, yellowish fluid, inflammable, incapable of combining with water, and nearly insoluble in alcohol. It is the lightest of all the fixed oils, and is very extensively used, particularly in Greece, Italy, Spain and France, as an article of food, and in medicine, and the arts.

The ripe fruit is gathered in November, and immediately bruised in a mill, the stones of which are set so wide as not to crush the kernel. The pulp is then subjected to the press in bags made of rushes; and by means of a gentle pressure, the best, or virgin oil, flows first; a second, and afterwards a third quality of oil is obtained by moistening the residuum, breaking the kernels, &c., and increasing the pressure. When the fruit is not sufficiently ripe, the recent oil has a bitterish taste, and when too ripe it is fatty. After the oil has been drawn, it deposits a white,

fibrous, and albuminous matter; but when this deposition has taken place, if it be put into clean glass flasks, it undergoes no farther alteration; the common oil cannot, however, be preserved in casks above a year and a half or two years. It is sometimes adulterated by the admixture of poppy oil.

The best olive oil is said to be made in the vicinity of Aix, in France. That which is brought from Leghorn in chests containing thirty bottles, or four English gallons, is also very superior. Olive oil is the principal article of export from the kingdom of Naples. By far the largest portion of the olive oil brought to this country is from Italy; but Spain supplies us with a considerable quantity.

ONYX: one of the semi-pellucid gems, with variously colored zones, but none red. It is found in different parts of the East Indies and in America.

OPAL: a stone, of which there are several varieties, found in different parts of Europe, particularly in Hungary; also in America and the East Indies. The color of the opal is white or pearl gray, and when held between the eye and the light is pale red, or wine yel

low, with a milky translucency. By reflected light, it exhibits, as its position is varied, elegant irridescent colors, particularly emerald green, golden yellow, flame and fire red, violet, purple, and celestial blue, so beautifully blended as to captivate the sight. When the color is arranged in small spangles, it takes the name of the harlequin opal. Sometimes it exhibits only one of the above colors, and of these the most esteemed are the vivid emerald green and the orange yellow. When the stone possesses the latter of these colors, it is called the golden opal.

The opal, in all ages, has been highly esteemed. The history of the Roman senator, who preferred death rather than give up his opal ring to the Emperor Nero, must be familiar to readers of ancient history. Among the Eastern nations, the opal ranks higher than in Europe.

OPHITES: a kind of variegated marble, of a dusky green ground, sprinkled with spots of a dark green color.

OPIUM: the concrete juice of the white poppy, which is most probably a native of Asia. Opium is chiefly prepared in India, Turkey,

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