PORK. 



POTATO. 



plant: they may exist as cortical pores; or 

 on the leaf as stornata or breathing pores. 

 Pores also exist in some kinds of anthers, 

 through which the pollen is ejected; as in the 

 potato (Solatium tuberosum*). 



PORK. The flesh of swine killed for culi- 

 nary purposes. See BACOX, HAM, MEAT, 



Swi VK. &C. 



PORTER. A well-known malt liquor. See 

 ALK, HKKII, and But: WIND. 



POTASH, or POTAS8A. The name of one 

 of the alkalies, composed of 39-15 parts of pe- 

 culiar metal called potassium, 8 parts of oxy- 

 gen, and 9 of water. It derives its common 

 name from being first obtained from the ashes 

 of vegetable substances which had been burn- 

 ed in iron pots, hence named pot-ashes. Pot- 

 ash is found in almost all land plants, in com- 

 bination with the tartaric, citric, or other vege- 

 table acid. The potash in these is no doubt an 

 essential food or constituent of vegetation, and 

 there is no fertile soil which does not, in some 

 form or other, contain this alkali. It exists, 

 however, in plants in varying proportions. 

 See ALKALI. The potash of commerce is an 

 impure carbonate mingled with salts of lime 

 and other substances. In its separate or pure 

 state, free from carbonic acid, it is a white 

 salt, powerfully attracting moisture from the 

 air, very soluble in water and in alcohol, cor- 

 roding animal substances, consequently de- 

 stroying the skin when applied to it. Bat pot- 

 ash usually means the carbonate. The quan- 

 tity procured from different plants varies. 

 Fumitory yields 79-0 in 1000 parts, worm- 

 wood 73-0, young wheat-stalks 47-0, thistles 

 3.VO, vetch 27-5, common nettle 25-3, the sun- 

 flower 20-0, bean-stalks 20-0, barley straw 5-8, 

 vine-shoots 5-5, wheat-straw 3-9, and flax 5-0. 

 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 alka- 

 lies, or alkaline earths, for when these sub- 

 stances are totally wanting, its growth will be 

 arrested, and when they are only deficient it 

 must be impeded. In order to apply these re- 

 marks, 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 al- 

 kalies 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 

 equisetaceoe, for example, contain, in the outer 

 parts of tJ>pir leaves and stalks, a large quantity 

 of silicic acid (silica), and potash in the form of 

 acid silicate of potash. The proportion of this 

 926 



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 o/ 

 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, cceteris paribus, 

 the best for meadow land, on account of the 

 quantity of potash which enters into their com- 

 position." 



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 dress- 

 ing, produced 157 bushels per acre, the land 

 dressed with 60 bushels of wood-ashes yielded 

 187; with 60 bushels of malt-dust, 184 bushels; 

 with 363 bushels of decayed leaves, 175 bush- 

 els ; with 363 bushels of saw-dust, 155 bushels; 

 with 121 bushels of lime, 150 bushels per acre. 

 (Com. Board ofjlgr. vol. iv. p. 370.) See GHEE* 

 SASTI), ALKALIS, and SALTS. 



POTATO (Solanum tuberosum). A 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 exten- 

 sively 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 if it is plough- 

 ed 5, 6, or 7 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 por- 

 duce such a crop as where the land is broken 

 18 inches to 2 feet. The potato, like the cu- 

 cumber, only enjoys itself in deeply pulverized 

 soils, which causes them to flourish so much 

 in well-managed sandy land. 



" 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 ro\vs ; say, in 

 ordinary land rows, at 2 feet from each other, 

 and 12 inches from set to set may do; but if 

 your land be very rich, 3 feet from row to row, 

 and 18 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, 



