POTASSIUM 





POTATO 



manufacture of a crude soap. Potash occurs in 

 all plants, and is found in large quantities in 

 rocks. The salt beds at Stassfurt, Germany, are 

 the chief source of the world's supply. America 

 usually imported about 900,000 tons yearly, and 

 when the War of the Nations cut off this sup- 

 ply in 1914. its preparation in the Unit* d EM 



inr necessary. It is obtained from feld-par 

 by heating it to a high temperature with lime- 

 -fone and iron oxide. Potash is used for fer- 

 tilizer, and in the manufacture of glass, gun- 

 powder, soap and some chemicals. 



POTASSIUM, potas'ium, a soft, silvery- 

 white metal, which when thrown upon \\ 

 bursts into flame. Potassium is one of the 

 chemical elements (see CHEMISTRY, subhead 

 'tienis) and is never found free in nature, 

 but in combination with other sub- 



ves in soils, in plants and in many rock.-. 

 about two and a half per cent of the earth's 

 crust being potassium. The potassium of com- 

 merce is obtained from potassium salts found 

 near Magdeburg, Germany. The salts are sub- 

 jected to a powerful electric current, which 

 fre.es the metal from its compounds (see ELEC- 

 TS). 



Pure potassium is but little used outside of 

 chemical laboratories. It is as soft as wax and 

 lighter than water, from which it withdraws the 

 oxygen so rapidly that the heat generated by 

 chemical action sets the hydrogen on fire. 

 Hence we say that potassium burns on water. 

 Because of its affinity for oxygen it has to be 

 kept in naphtha. 



Potassium is an element of plant food, and 

 some of its compounds are used as fertilizer. A 

 soil deficient in potassium will not produce good 

 -. Some potassium compounds are exten- 

 ly used in the arts. The carbonate, or pot- 

 ash, and the nitrate, or saltpeter, are described 

 under their titles. The hydroxide, or caustic 

 potash, on exposure to the air or win n <h-- 

 solved in water changes to the carbonate. All 

 solut. lie above-named compounds are 



dy alkaline (see ALKALI). Potassium cya- 

 is very poisonous. It is used in photog- 

 raphy and in dyrinn. The sulphate commonly 

 vn as plaster is used as fernli/.. r. The bro- 

 and iodide are used in medicine, and tin 

 ;ide is employed in the manufacture of 



potassium compounds. 



POTATO, pota'to, the most popular and 

 getable in the world, belonging 

 iio same family as the ni^ht-hade, the to- 

 bacco plant and the tomato. In v i\ . 

 co u ir perate zone the potato crop 



ranks next to the cereal crop. But this has not 

 i been the case. Until Columbus dis- 

 covered America and the early explorers had 

 carried some of the curious plants of the New 

 World back to the Old, potatoes were unknown 

 in Europe. They were not even known in 

 North America until after the middle of the 

 .ih century, when they were first brought 

 to Virginia from Peril. The name "Irish" is 



HOW POTATOES APPEAR UNDERGROUND 

 At the left Is shown the formation of the IO.L 



applied to the plant because the introduction 

 of potato culture into Ireland saved the people 

 from the terrible famines that had often devas- 

 tated the country, and not because they are 

 native to the island. 



Description and Culture. The potato plant 

 grows from one to three feet high, and bears 

 white or purple flowers and a round, purplish 

 fruit about as large as a gooseberry. The 1 

 is the seedball of the plant. The edible part is 

 not the root, but a tuber, or underground stem. 

 and the "eyes" are stem buds. New plants may 

 be grown from seeds or from old potato* 

 pieces of potatoes containing "eyes," but t 

 is a striking difference in the results obtained. 

 An old potato used as seed will yield the same 

 variety of tuber over again, while the tubers of 

 plants grown from seeds will show considerable 

 variation from the parent >toek. The Hurbank 

 potato is the result of experimentation with 

 seed planting. 



Potatoes do best in well-drained, sandy loam. 

 and they respond readily to enrichment of t he- 

 soil. According to reports received from 

 rious experiment stations, best results arc ob- 



t lined when (ine-half a tuber i- u-. d Ofl a - 1 



piece, or "set . urable conditions 



twenty bushels Of Seed (half-potatoes) to th- 



acre will yield about 320 bushels per a 

 tubers are planted from a foot to sixteen it 

 apart in the row, and are cover, d with earth 

 four inches deep. Frequent harrowing of the 

 soil until the plants are above ground and thor- 

 ough cultivation thereafter are necessary. 





