Our invaluable Potato, which enters so largely into the dietary of all classes, belongs to the Nightshade tribe of dangerous plants, though termed "solanaceous" as a natural order because of the sedative properties which its several genera exercise to lull pain.
This Potato, the Solanum tuberosum, is so universally known as a plant that it needs no particular description. It is a native of Peru, and was imported in 1586 by Thomas Heriot, mathematician and colonist, being afterwards taken to Ireland from Virginia by Sir Walter Raleigh, and passing from thence over into Lancashire. He knew so little of its use that he tried to eat the fruit, or poisonous berries, of the plant. These of course proved noxious, and he ordered the new comers to be rooted out. The gardener obeyed, and in doing so first learnt the value of their underground wholesome tubers. But not until the middle of the eighteenth century, were they common in this country as an edible vegetable. "During 1629," says Parkinson, "the Potato from Virginia was roasted under the embers, peeled and sliced: the tubers were put into sack with a little sugar, or were baked with cream, marrow, sugar, spice, etc., in pies, or preserved and candied by the comfit makers." But he most probably refers here to the Batatas, or sweet Potato, a Convolvulus, which was a popular esculent vegetable at that date, of tropical origin, and to which our Potato has since been thought to bear a resemblance.
This Batatas, or sweet Potato, had the reputation, like Eringo root, of being able to restore decayed vigour, and so Falstaff is made by Shakespeare to say: "Let the sky rain potatoes, hail kissing comfits, and snow eringoes." For a considerable while after their introduction the Potato tubers were grown only by men of fortune as a delicacy; and the general cultivation of this vegetable was strongly opposed by the public, chiefly by the Puritans, because no mention of it could be found in the Bible.
Also in France great opposition was offered to the recognised use of Potatoes: and it is said that Louis the Fifteenth, in order to bring the plant into favour, wore a bunch of its flowers in the button hole of his coat on a high festival. Later on during the Revolution quite a mania prevailed for Potatoes. Crowds perambulated the streets of Paris shouting for "la liberté, et des Batatas"; and when Louis the Sixteenth had been dethroned the gardens of the Tuileries were planted with Potatoes. Cobbett, in this country, exclaimed virulently against the tuber as "hogs' food," and hated it as fiercely as he hated tea. The stalks, leaves, and green berries of the plant share the narcotic and poisonous attributes of the nightshades to which it belongs; and the part which we eat, though often thought to be a root, is really only an underground stem, which has not been acted on by light so as to develop any poisonous tendencies, and in which starch is stored up for the future use of the plant.
The stalks, leaves, and unripe fruit yield an active principle apparently very powerful, which has not yet been fully investigated. There are two sorts of tubers, the red and the white. A roasted Potato takes two hours to digest; a boiled one three hours and a half. "After the Potato," says an old proverb, "cheese."
Chemically the Potato contains citric acid, like that of the lemon, which is admirable against scurvy: also potash, which is equally antiscorbutic, and phosphoric acid, yielding phosphorus in a quantity less only than that afforded by the apple, and by wheat. It is of the first importance that the potash salts should be retained by the potato during cooking: and the tubers should therefore be steamed with their coats on; else if peeled, and then steamed, they lose respectively seven and five per cent. of potash, and phosphoric acid.
If boiled after peeling they lose as much as thirty-three per cent. of potash, and twenty-three per cent. of phosphoric acid. "The roots," says Gerard, "were forbidden in Burgundy, for that they were persuaded the too frequent use of them causeth the leprosie." Nevertheless it is now believed that the Potato has had much to do with expelling leprosy from England. The affliction has become confined to countries where the Potato is not grown.
Boiled or steamed Potatoes should turn out floury, or mealy, by reason of the starch granules swelling up and filling the cellular tissue, whilst absorbing the albuminous contents of its cells. Then the albumen coagulates, and forms irregular fibres between the starch grains. The most active part of the tuber lies just beneath the skin, as may be shown by pouring some tincture of guaiacum over the cut surface of a Potato, when a ring of blue forms close to the skin, and is darkest there while extending over the whole cut surface. Abroad there is a belief the Potato thrives best if planted on Maundy Thursday. Rustic names for it are: Taiders, Taities, Leather Coats, Leather Jackets, Lapstones, Pinks, No Eyes, Flukes, Blue Eyes, Red Eyes, and Murphies; in Lancashire Potatoes are called Spruds, and small Potatoes, Sprots.
The peel or rind of the tuber contains a poisonous substance called "solanin," which is dissipated and rendered inert when the whole Potato is boiled, or steamed. Stupes of hot Potato water are very serviceable in some forms of rheumatism. To make the decoction for this purpose, boil one pound of Potatoes (not peeled, and divided into quarters.) in two pints of water slowly down to one pint; then foment the swollen and painful parts with this as hot as it can be borne. Similarly some of the fresh stalks of the plant, and its unripe berries, as well as the unpeeled tubers cut up as described, if infused for some hours in cold water, will make a liquor in which the folded linen of a compress may be loosely rung out, and applied most serviceably under waterproof tissue, or a double layer of dry flannel. The carriage of a small raw Potato in the trousers' pocket has been often found preventive of rheumatism in a person predisposed thereto, probably by reason of the sulphur, and the narcotic principles contained in the peel. Ladies in former times had their dresses supplied with special bags, or pockets, in which to carry one or more small raw Potatoes about their person for avoiding rheumatism.
If peeled and pounded in a mortar, uncooked Potatoes applied cold make a very soothing cataplasm to parts that have been scalded, or burnt. In Derbyshire a hot boiled Potato is used against corns; and for frost-bites the mealy flour of baked potatoes, when mixed with sweet oil and applied, is very healing.
The skin of the tuber contains corky wood which swells in boiling with the jackets on, and which thus serves to keep in all the juices so that the digestibility of the Potato is increased; at the same time water is prevented from entering and spoiling the flavour of the vegetable. The proportion of muscle-forming food (nitrogen) in the Potato is very small, and it takes ten and a half pounds of the tubers to equal one pound of butcher's meat in nutritive value.
The Potato is composed mainly of starch, which affords animal heat and promotes fatness, The Irish think that these tubers foster fertility; they prefer them with the jackets on, and somewhat hard in the middle--"with the bones in." A potato pie is believed to invigorate the sexual functions.
New Potatoes contain as yet no citric acid, and are hard of digestion, like sour crude apples; their nutriment, as Gerard says, "is sadly windy," the starch being immature, and not readily acted on by the saliva during mastication. "The longer I live," said shrewd Sidney Smith, "the more I am convinced that half the unhappiness in the world proceeds from a vexed stomach, or vicious bile: from small stoppages, or from food pressing in the wrong place. Old friendships may be destroyed by toasted cheese; and tough salted meat has led a man not infrequently to suicide."
A mature Potato yields enough citric acid even for commercial purposes; and there is no better cleaner of silks, cottons, and woollens, than ripe Potato juice. But even of ripe Potatoes those that break into a watery meal in the boiling are always found to prove greatly diuretic, and to much increase the quantity of urine.
By fermentation mature Potatoes, through their starch and sugar, yield a wine from which may be distilled a Potato spirit, and from it a volatile oil can be extracted, called by the Germans, Fuselöl. This is nauseous, and causes a heavy headache, with indigestion, and biliary disorders together with nervous tremors. Chemically it is amylic ether.
Also when boiled with weak sulphuric acid, the Potato starch is changed into glucose, or grape sugar, which by fermentation yields alcohol: and this spirit is often sold under the name of British brandy.
A luminosity strong enough to enable a bystander to read by its light issues from the common Potato when in a state of putrefaction. In Cumberland, to have "taities and point to dinner," is a figurative expression which implies scanty fare. At a time when the duty on salt made the condiment so dear that it was scarce in a household, the persons at table were fain to point their Potatoes at the salt cellar, and thus to cheat their imaginations. Carlyle asks in Sartor Resartus about "an unknown condiment named 'point,' into the meaning of which I have vainly enquired; the victuals potato and point not appearing in any European cookery book whatever."
German ladies, at their five o'clock tea, indulge in Potato talk (Kartoffel gesprach) about table dainties, and the methods of cooking them. Men likewise, from the four quarters of the globe, in the days of our childhood, were given to hold similar domestic conclaves, when:--
"Mr. East made a feast, Mr. North laid the cloth, Mr. West brought his best, Mr. South burnt his mouth Eating a cold Potato."
With pleasant skill of poetic alliteration, Sidney Smith wrote in ordering how to mix a sallet:--
"Two large Potatoes passed through kitchen sieve, Unwonted softness to a salad give."
And Sir Thomas Overbury wittily said about a dolt who took credit for the merits of his ancestors: "Like the Potato, all that was good about him was underground."