(See Garlic).

The chemical constituents of an Onion-bulb are an acrid volatile oil, sulphur, phosphorus, alkaline earthy salts, phosphoric and acetic acids, phosphate, and citrate of lime, starch, sugar, and cellulose. Onion juice becomes of a rose-red colour when exposed to the air; it contains sugar, and will therefore ferment, even until yielding alcohol; the outer harder coats contain oxalate of lime. The Onion was long believed to specifically prevent the intoxicating effects of alcoholic drink, and to dispel its evil consequences. The large Spanish Onion is rich enough in nutrients to be regarded as a food. American growers have developed the same into the big, silvery-looking, gleaming white Onions on sale in the markets, which are still called Spanish, though they have in fact been no nearer Spain than the New England States, or New Jersey. These Onions are so mild and tender, that anyone can eat them when boiled, or stewed, without ill-effects; they are said to induce a pleasant desire for sleep. A labourer in Spain will munch an Onion just as an English rustic does an apple. The Spanish Onion, grown largely in Portugal, cannot be acclimatized in England: it soon degenerates with us.

Dishes which contain Onions in any quantity, or are strongly flavoured therewith, are said to be cooked " ala Soubise;" the name being supposed to come from Prince Charles Soubise (1750), who was a famous epicure Field-marshal during the reign of Louis the Fourteenth of France. Another classical appellation of the Onion is "Cepe;" which schoolboys take advantage of for their puzzle line, "Scepe cepi cepe, sub sepe".

Onions are helpful against constipation, by reason mainly of their abundant cellulose, which gives intestinal momentum. Many persons are led to think that these, in common with the leek, and garlic, are of service against fatigue from such prolonged exercise as is entailed by hunting, shooting, etc., and subsequent feasting. For bronchitis it has proved of use to apply repeatedly over the chest a good-sized Onion, beaten into pulp, within a flannel bag, each application being for four hours. A syrup made from the fresh juice of raw Onions, with honey, is an excellent medicine for old persons troubled with phlegm in cold weather, when the air passages are stuffed, and free breathing is hindered. Raw Onions increase the flow of urine, and promote free perspiration, insomuch that a diet of them with bread has many a time dispersed dropsical effusions caused by a chill, with arrested circulation in the kidneys, and skin surface. The volatile principle which benefits in this stimulating manner is sulphide of allyl, an acrid salt.

The chief internal effects of these, and their kindred bulbs, are increase of warmth, and of circulatory vigour; so that they are better adapted for patients of a cold temperament, and sluggish energies, than when the system is feverish, and the constitution ardently excitable. "Vous tous qui etes gros, et gras, et lymphatiques, avec l'estomac paresseux, mangez I'oignon cru; c'est pour vous que le bon Dieu la fait".

A jorum (or earthen bowl) of hot Onion broth taken at bedtime will serve admirably to mollify the air passages, and to open the skin-pores, after the first feverish stage of catarrh, or influenza, has passed by. To make this, peel a large Spanish Onion, and divide it into four parts; put them into a saucepan with half a saltspoonful of salt, and two ounces of butter, also a pint of cold water; let them simmer gently until quite tender; next pour all into a bowl which has been made hot, dredging a little pepper over; and let the broth be taken as hot as it can be borne. The allyl, and sulphur in the bulbs, together with their mucilage, relieve the sore, raw mucous membranes, and exercise a specific medicinal virtue which they possess for cure, as has been conclusively shown by experimental provings. Onion gruel is similarly an excellent, and delicious posset for a catarrhal patient, this being made of either water, or milk, and proving smooth enough for any palate if patent groats are used. The Onion should be three-parts cooked in the water, and finished in the gruel.

For a full-flavoured gruel English Onions should be used; or, for a mild gruel, Portugal, or Egyptian Onions. Some persons prefer to boil them the whole time in the liquid for the gruel, thus retaining certain properties which are anti-asthmatic. If butter is liked, add a morsel of the freshest, off the fire, or a spoonful of cream instead. Onion milk is a time-honoured remedy for a similar purpose, and is to be prepared in the same way, adding a clove, a morsel of mace, or a little whole allspice, to simmer in the milk; this beverage to be served quite hot. But, after all, cold-catching can be prevented beforehand, which is far better than having necessary recourse subsequently to these palliative measures. A white-haired old travelling tinker, hardy and hearty, testifies thus, for instance: "Sometimes one of the Deacons says to me when he sees me outside o' th' Chapel i' th' yard, athowt mi yed covered, 'Aw wish aw could stand i' th' wind an' rain athowt mi hat on, athowt catchin' cowld, Sam, as yo' can.' An' says aw to him, 'Th' mon as wears flannel next his skin, an' as dips his yed under cowld water three times every mornin', doesno catch much cowld; aw've seen eighty-two buthdays, and, thank the Lord, aw hanno' got a pain, or a ache about me".

If employed as a poultice for ear-ache, or for broken chilblains, the Onion should be plainly roasted, so as to modify its acrid oil. When there is a running fetid discharge from the ear, or when an abscess is first threatened, with pain, heat, and swelling, the hot poultice of roasted Onion will be found very soothing, and will do much to mitigate the pain; or, a clove of Garlic, stripped of the outer skin, and cut in the form of a blunt cone, if thrust gently into the ear of the aching side, will quickly assuage the pain. "Onyon juice," saith an old maxim, "anoynted on the bald head in the sun, bringeth the haire againe very speedilie." For inflamed, and protruding piles, the raw Onion pulp of a bruised bulb will, if kept bound close against the part by a compress, and renewed as needed, afford certain relief. Small Onions eaten at night by those persons who are not prone to feverishness, will promote sleep, and induce a gentle perspiration. The late Frank Buckland said: "I am sure the essential oil of Onions has specific powers; in my own case it never fails; if I am much pressed with work, and feel that I am not disposed to sleep, I eat two or three small Onions, and their effect is magical".