PORES.

nches of clay, at a cost of only 167. This as formed a plate to retain what mould, e, the tenant has added, who has hired his ground for fourteen years, at 408. per ere. So no land is hopelessly barren. Let uch improvements proceed; let science o hand in hand with the farmer; let e naturalist find new cultivateable vegebles, or new varieties of those already nown; let the chemist yield his magic aid demonstrate the best mode of promoting eir growth and increasing the fertility of e soil; and then, I fearlessly assert, that any times the present inhabitants of Briin may be amply supported by the proice of the land of our birth.

PORES. In botany, apertures, more or ss visible, in the cuticle of plants through hich transpiration takes place. They may ist on the cellular tissue; and when there ey are the organs of insensible perspiraons of the plant: they may exist as coral pores; or on the leaf as stomata or eathing pores. Pores also exist in some nds of anthers, through which the pollen ejected; as in the potato (Solanum tuberum).

PORK. The flesh of swine killed for
linary purposes. See BACON, HAM, MEAT,
WINE, &c.
PORTER.

A well known malt liquor.

e ALE, BEER, and BREWING. POTASH, or POTASSA. The name of e of the alkalies, composed of 39 15 parts 'peculiar metal called potassium, 8 parts of <ygen, and 9 of water. It derives its comon name from being first obtained from e ashes of vegetable substances, which ad been burned in iron pots-hence named ot-ashes. The chemical name potassa, is tended to be consistent with soda. Potash found in almost all land plants, in comination with the tartaric, citric, or other egetable acid. The potash in these is no oubt an essential food or constituent of egetation, and there is no fertile soil which oes not in some form or other contain this Ikali. It exists, however, in plants in arying proportions. See ALKALI. The otash of commerce is an impure carbonate ningled with salts of lime, and other subtances. In its separate or pure state, free rom carbonic acid, it is a white salt, powerfully attracting moisture from the air, very soluble in water and in alcohol, corroding animal substances, consequently destroying the skin when applied to it. But potash usually means the carbonate. The quantity procured from different plants varies. Fumitory yields 790 in 1000 parts, wormwood 730, young wheat-stalks 47'0, thistles 35 0, vetch 27.5, common nettle 25.3, the sun-flower 20-0, bean-stalks 20-0, barley

POTATO.

straw 5.8, vine-shoots 5.5, wheat-straw 3.9, and flax 50. The younger a plant is, if full grown, the more potash it yields.

"The perfect developement of a plant," says Liebig, (Organic Chem. p. 104.), “according to this view, is dependent on the presence of alkalies, or alkaline earths, for when these substances are totally wanting, its growth will be arrested, and when they are only deficient it must be impeded. In order to apply these remarks, let us compare two kinds of trees, the wood of which contain unequal quantities of alkaline bases, and we shall find that one of these grows luxuriantly in several soils, upon which others are scarcely able to vegetate. For example, 10.000 parts of oak wood yield 250 parts of ashes, the same quantity of fire-wood only 83, of linden wood 500, of rye 440, and of the herb of the potato plant 1500 parts. Firs and pines find a sufficient quantity of alkalies in granitic, and barren sandy soils; in which oaks will not grow, and wheat thrives in soils favourable for the linden tree, because the bases which are necessary to bring it to complete maturity exist there in sufficient quantity. The accuracy of these conclusions, so highly important to agriculture, and to the cultivation of forests, can be proved by the most evident facts. All kinds of grasses, the equisetaceæ, for example, contain, in the outer parts of their leaves and stalks, a large quantity of silicic acid (silica), and potash in the form of acid silicate of potash. The proportion of this salt does not vary perceptibly in the soil of corn fields, because it is again conveyed to them as manure, in the form of putrefying straw. But this is not the case in a meadow: and hence we never find a luxuriant crop of grass on sandy and calcareous soils, which contain little potash, evidently because one of the constituents essential to the growth of plants is wanting. Soils formed from basalt, grauwacke, and porphyry, are, cæteris paribus, the best for meadow land, on account of the quantity of potash which enters into their composition."

In the experiments of the Rev. E. Cartwright with various manures applied to potatoes, wood ashes, which contain potash, were found to produce very superior effects to several others: thus, where the soil, without any dressing, produced 157 bushels per acre, the land dressed with 60 bushels of wood ashes yield 187; with 60 bushels of malt dust, 184 bushels; with 363 bushels of decayed leaves, 175 bushels; with 363 bushels of saw-dust, 155 bushels; with 121 bushels of lime, 150 bushels per acre. (Com. Board of Agr. vol. iv. p. 370.) See SALTS.

Α

POTATO. (Solanum tuberosum.) valuable well-known root, first imported from America into England by Sir Walter

Raleigh, and first grown at Youghall, in Ireland. In many parts of England this tuberose plant is very extensively cultivated, both in the field and in the garden; but, in districts removed from large towns, or convenient markets, its cultivation is of necessity restricted to the garden, or for the consumption of the live stock of the farm. As regards the field management of the crop, a writer in a popular journal remarks, when speaking of the preparation of the ground:

"It is, I know, customary upon a large scale, to plough the land and make it tolerably fine before potatoes are planted; but still, if it is ploughed five, six, or seven inches deep, and made fine and mellow, still at the bottom of such ploughing the land is hard and smooth; and as the potato is a root that sends out fibres not only near the surface, but deeply if possible, it can never produce such a crop as where the land is broke eighteen inches to two feet. The potato, like the cucumber, only enjoys itself in deeply pulverised soils, which causes them to flourish so much in well-managed sandy land.

66

"I should therefore recommend that, in all land where potatoes are to be grown, if the land be springy or otherwise damp, that it be drained deep enough to take off all springs or surface water. When this is done, the land should either be fully trenched, or bastard trenched, by the spade or plough, but I prefer the spade. The width of the drills from each other must depend entirely upon the goodness of your soil the richer the land, the wider apart must be your rows and sets in your rows, say, in ordinary land rows, at two feet from each other, and twelve inches from set to set may do; but if your land be very rich, three feet from row to row, and eighteen inches from plant to plant, will not be too much."

In preserving your sets, always select the largest and finest potatoes you can procure; do not use the small refuse or middling-sized, the plant and produce from the latter being much inferior.

The potatoes most valued in field culture are the ox-noble, yam, champion, purple red, rough red, hundred eyes, kidney, and Moulton white. The nutritive qualities of these were examined by Mr. George Sinclair, with his usual accuracy. "The yam," he observes," is a very productive variety, attains to a large size, but is often hollow, and less nutritive than most others. 64 drachms afford of nutritive matter 190 grains, which consist of starch 164 grains, and saccharine and albuminous matters 31. The ox-noble is a productive potato, adapted for stock; and 64 drachms of it

contain 194 grains of nutritive matter, consisting of starch 164, and saccharine, nucilaginous, and albuminous matters 31.

The purple red is smaller than the exnoble, but well-flavoured, and very profic in light moist soils: 64 drachms afforded 200 grains of nutritive matter, consisting of starch 169, and albuminous and se charine matters 31 grains.

The hundred eye is very prolific on dry loams; 64 drachms afford 218 grains d nutritive matter, composed of 170 grains of starch, and the rest albuminous and other

The soluble matters consisted of gun, r mucilage, extractive, and saline matters (Sinclair's Hort. Gram. p. 409.)

The potato, although a tender plant, is grown in nearly all parts of the world, from the equator to Norway; and although its usual to plant it early in the spring, yet i is possible, by choosing a quick ripening variety, to plant it successfully even as int as July.

The manures best suited for the potato crop, are common farm-yard compost only partially decomposed, decayed leaves, seaweed, the potato haulm, and any organic manures, that, while they afford nutriment have a tendency, by rendering the soil lighte to facilitate the extension of the ro Lime is injurious to it. Pond mad ditch scrapings to each cubic yard of which a month previously, a bushel of bacon salt, or other refuse common salt, has bea mixed, is excellent. The soils best adsped for the cultivation of the potato are of the light, sandy, drained, peaty or loamy deser

The varieties of the potato are numerous, d continually increasing, as well as bening extinet; the number, however, is ry largely increased by local names for e same variety being classed distinct. For forcing, or first crop in the open ound-there are Broughton dwarf, early arwick, ash-leaved kidney; Fox's seedg, early manly, early mule, earliest for neral cultivation, early kidney, nonsuch, ly shaw, goldfinder.

For main crops, the varieties are ranged this class, according to their forwardness ripening:-early champion, ox noble, 1-nose kidney, large kidney, bread fruit, 1-streak or Lancashire pink eye, black in, purple, red apple, rough red.

No inhabitant of the garden varies more quality in different gardens than the poo; for a variety will have a strong uneasant flavour in one soil, that has a sweet reeable one in another. In a heavy, wet 1, or a rank black loam, though the crop often fine and abundant, it is scarcely er palatable. Silicious soils, even apoaching to gravel, though in these last e tubers are usually corroded or scabby, e always to be planted in preference to e above. A dry, mouldy, fresh, and morately rich soil is unquestionably the best r every variety of the potato; and, for the rliest crop, it may be with advantage ore silicious than for the main ones. The lack-skinned and rough red thrive better an any in moist or strong cold soils. If anure is necessary, whatever may be the ne employed, it is better spread regularly ver the surface previous to digging, rather han put into the holes with the sets, or pread in the trench when they are so lanted. Stable-dung is, perhaps, the best of all factitious manures: sea-weed is a very eneficial addition to the soil, as is salt. Coal-ashes and sea-sand are applied with great benefit to retentive soils; but calcareous matter should never be used. The situation must always be open.

It is propagated in general from cuttings

of the tubers, though the shoots arising from thence and layers of the stalks may be employed. New varieties are raised from seed. Planting in the open ground of the early kinds may commence towards the close of February, in a warm situation, and may thence be continued until the same period of March; and it is only during this latter month that any considerable plantation should be made, as the late frosts are apt to injure, or even destroy the advancing plants. In the course of April, the main crops for winter's use should be inserted; for although in favourable seasons they will succeed if planted in May or even June, yet it ought always to be kept in mind that the earliest planted, especially in dry soils, produce the finest and most abundant crops.

Of the preparation of the sets, there is a great diversity of opinion. Some gardeners recommend the largest potatoes to be planted whole; others, these to be sliced into pieces, containing two or three eyes; a third set, to cut the large tubers directly in half; a fourth, the employment of the shoots only which are thrown out, if potatoes are kept in a warm, damp situation; and a fifth, that merely the parings be employed. Cuttings of the stalks, five or six inches in length, or rooted suckers, will be productive, if planted during showery weather in May or June; and during this last month, or early in July, it may be propagated by layers, which are formed by pegging down the young stalks when about twelve inches long, they being covered three inches thick with mould at a joint. These three last modes are practised more from curiosity than utility, whilst at the same time none of the first five mentioned plans can be individually followed to advantage, without modification. For the main crops, it is evident, from experiment, that moderate sized sets, having two healthy buds or eyes, are most advantageously employed; middling sized whole potatoes are the best, from which all but the above number of eyes have been removed, but especially having the crown, which is a congeries of small eyes always present, first removed; for from these proceed an equal number of little spindled stalks, which are comparatively worthless, and injure the main stem.

For the early crops, almost the very contrary to the above is the most advantageous to be practised. The set should have the crown eye, which is one growing in the centre of the congeries of small ones above mentioned, preserved. Some potatoes have two such eyes, but the generality only one. This is always the most prompt to vegetate; and if not known by this description, may be evinced by placing two or three potatoes in a pan of moist earth, near the

earth is kept moist, the crown eye will be in a state of vegetation in five or six days. (Pract. Treat. on the Culture of the Potato, p. 20.) Again, as Mr. J. Knight remarks, although abundant crops of late varieties may be obtained from very small sets, by reason that tubers are not produced until the stem and roots become capable of supplying them with nourishment; yet, to obtain early crops, where tubers are rapidly formed under a diametrically opposite state of the plant, large sets must be employed; in these, one or two eyes, at most, should be allowed to remain. Mr. Knight plants the largest undivided tubers, which, from experiments, evidently support the plants, and finally produce the earliest and largest produce he ever obtained. Another remark, which he makes, restrictively for the early crops, but may well be attended to for all, is, that if the sets are placed with their leading buds upwards, few and very strong early stems will be produced; but if the position is reversed, many weak and later shoots will arise, and not only the earliness, but the quality of the produce be depreciated. (Trans. Hort. Soc. Lond. vol. iv. p. 448.) For the earliest crops, there are likewise several modes of assisting the forward vegetation of the sets. These should be prepared in November, by removing every eye but one or two; and being placed in a layer, in a warm room, where air and light can be freely admitted, with a covering of straw, they soon emit shoots, which must be strengthened by exposure to the air and light as much as possible, by taking off the covering without injuring them. During cold weather, and at night, it must always be renewed. The leaves soon become green, and tolerably hardy. In early spring they are planted out, the leaves being left just above the surface, and a covering of litter afforded every night, until the danger of frost is passed. The only modification of this plan that is adopted in Cheshire, where they are celebrated for the early production of potatoes, is, that they employ chaff or sand for a covering instead of straw. (Holland's Agr. Survey of Cheshire.) The most preferable mode of inserting them, is with the dibble, in rows, for the early crops, twelve inches apart each way; and for the main ones, eighteen. The set should never be placed more than four inches beneath the surface in the lightest soil, but in the more tenacious ones, three is the extreme. The potato dibble is the best instrument that can be employed; one person striking the holes, and a second dropping the sets, the earth being afterwards raked or struck in with the spade. There are several other modes of insertion, as opening a small hole

with a narrow spade, and the set being dropped in, it is covered by the earth taket out in forming the next hole: or, at the time of digging over the ground, a second pers follows the one so employed, and places the sets in the trench he opens in the pursuance of his work; but both these modes are open to numerous obvious objections.

The compartment may be laid out levi and undivided, if the soil is mouldy m favourable; but if a heavy one is neces sarily employed, it is best disposed in bedsix or eight feet wide. If the staple of the soil is good throughout, the alleys may two feet wide, and dug deep, otherwise lev must be made broader, and only one t taken out, the earth removed being e ployed to raise the beds. If the land low and wet, it is still further of advant after the beds, which should not be than four feet wide, have been thus raise. if they are dug in parallel ridges, and t sets inserted along their summits. S gardeners, on such soils, without de:the surface, lay some long litter on the a tended beds; upon this the sets b placed, some more litter is thrown regulari over them; the earth is then dug from t alleys, and turned to the requisite de over the whole. As soon as the plants well to be distinguished, they should perfectly freed from weeds; and, of 2early crops, the earth drawn round plant, so as to form a cup, as a shelter f the cold winds, which are their chief ca at that season; but the main crops need be earthed up until the plants are six in in height. It is contended by some this practice is immaterial in its ef (Bath Papers, vol. i. p. 28.) If the ear brought so as to be of considerable depa about the stems, it must be even injur but if properly performed it is certat beneficial. Throughout their growth should be kept perfectly clear of we It is very injurious to mow off their 1 as is sometimes recommended. The fe ought to be kept as uninjured as possit 4 unless, as sometimes occurs on fresh gre the plants are of gigantic luxuriance, an even then, the stems should be only m rately shortened. It is, however, of siderable advantage to remove the t stalks and immature flowers as soon as the appear. This has been demonstrated the experiments of President Kright, others; indeed, that such would be the ca is a reasonable expectation, since it is ka that the early formation of tubers prent the production of blossom. (Tra Soc. Lond. vol. i. p. 188.) It is also wan of notice, that a potato plant continue form tubers until the flowers appear,

hich it is employed in ripening those alady formed.

The very earliest crops will be in proction in June, or perhaps towards the end May, and may thence be taken up as unted, until October, at the close of which nth, or during November, they may be tirely dug up and stored; or, at all events, fore the arrival of any severe frost. Their ess to be taken up for keeping is intited by the decay of their foliage, which erally loses its verdure with the first sts. The best instrument with which y can be dug up is a three-flat-pronged k, each row being cleared regularly away. e tubers should be sorted at the time of ing them up; for as the largest keep the t, they alone should be stored, whilst the aller ones are first made use of. The st common mode of preserving them oughout the winter is in heaps or clamps, etimes called pyeing them. These are I in pyramidal form, on a bed of straw, I enveloped with a covering, six or eight hes thick, of the same material, laid even, in thatching, and the whole enclosed h earth, in a conical form, a foot thick, en from a trench dug round the heap, I smoothened with the back of the spade. tatoes should not be stored until perfectly , nor unless free from mould, refuse, I wounded tubers. It is a good practice keep a hole open on four different sides the heap, entirely through the mould and aw, for a week or two after the heap is med; for in proportion to its size it alys ferments, and these orifices allow the ape of the vapours, and perfect the dryAn equally good mode, and much re convenient, is to have them heaped in ry shed, and covered thick with straw, opportunity is given to look over them asionally for the removal of decayed pers, shoots, &c. If carefully preserved, y continue in perfection until late in the lowing summer. A variety of the potato generally considered to continue about urteen years in perfection, after which riod it gradually loses its good qualities, coming of inferior flavour and unproduce. Fresh varieties must therefore be ocsionally raised from seed. For doing this ere are two modes; the first of these, out to be detailed, is, however, the one nally pursued.

The berries or apples of the old stock ving hung in a warm room throughout e winter, the seed must be obtained from em by washing away the pulp during bruary. This is thoroughly dried, and pt until April, and then sown in drills out half an inch deep, and six inches art, in a rich mouldy soil. The plants

| are weeded, and earth drawn up to their stems when an inch in height; as soon as this has increased to three inches, they are moved into a similar soil, in rows sixteen inches apart each way, and during their future growth earthed up two or three times. Being finally taken up in the course of October, they must be preserved until the following spring, to be then replanted, and treated as for store crops. (Dr. Hunter's Georg. Essays.)

Some gardeners sow in a moderate hotbed, very thin, in drills, the same depth as above, and nine inches apart. Water is frequently and plentifully poured between the rows, and earth drawn about the stems of the seedlings, until they are a few inches in height. They are then transplanted into rows, water given, and earthing performed as usual. The only additional advantage of this plan is, that as the seed can be sown earlier, the tubers attain a rather larger size the first year.

It is to be remarked, that the tubers of every seedling should be kept separate, as scarce two will be of a similar habit and quality, whilst many will be comparatively worthless, and but few of particular excellence. If the seed is obtained from a red potato, that flowered in the neighbourhood of a white tubered variety, the seedlings in all probability will in part resemble both their parents, as a cross fecundation may take place; but seldom or never does a seedling resemble exactly the original stock. At all events, only such should be preserved as are recommended by their superior size, flavour, or fertility. It may be stated as an indication before these qualities can be positively ascertained, that President Knight remarks, that the rough uneven surface of the foliage, which in excess constitutes the curl, appears to exist as, and form a characteristic of every good variety; for he never found one with perfectly smooth and polished leaves which possessed any degree of excellence, though such are in general more luxuriant and productive. (Trans. Hort. Soc. Lond. vol. ii. p. 64.)

The early varieties, on account of their never flowering, were, until 1807, obtained by chance from plants that might now and then be produced from seed of the late kinds. In that year, Mr. Knight discovered that the cause of their deficiency of bloom was the preternatural early formation of the tubers. His mode of causing them to produce seed is to plant the sets on little heaps of earth, with a stake in the middle, and when the plants are about four inches high, being secured to the stakes with shreds and nails, to wash the earth away from the bases of the stems, by means