ALKALI 



clear liquid remaining is found to be a much 

 more active lye than the original solution, 

 and if the water is evaporated off, the white 

 substance left is found to be much more 

 soluble in water than the original carbonate. 

 This product is called a caustic alkali, since it 

 not merely softens but actually dissolves ani- 

 mal tissues. The caustic alkalies are the 

 hydroxides (compounds with hydrogen and 

 oxygen) of the metals of which the jjiild alka- 

 lies are the carbonates. The majority of 

 modern writers on chemistry limit the term 

 alkali to the caustic alkalies, but speak of all 

 substances that effect litmus similarly as being 

 alkaline or having an alkaline reaction. In 

 addition to sodium and potassium, the ele- 

 ments lithium, rubidium and caesium have 

 hydroxides which are caustic alkalies. These 

 five metals, accordingly, are known as the 

 alkali metals, or metals of the alkalies. Am- 

 monia water, which resembles the caustic 

 alkalies in its chemical action, is called the 

 volatile (that is, flying) alkali, because it will 

 all evaporate away. In contradistinction the 

 original alkalies (mild or caustic) are termed 

 fixed. The oxide of calcium (which is quick- 

 lime) and those of strontium and barium are 

 called the alkaline earths, and these elements 

 the alkaline earth metals. 



Alkali la?ids are soils which contain so large 

 a proportion of soluble salts as to prevent or 

 interfere with the growth of plants. These 

 salts may come from underground deposits of 

 sea salt left by the drying up of ancient seas. 

 In a greater number of instances they have 

 probably originated in that action of water 

 and carbonic acid on the rocks by which the 

 1 itself has been formed. In dry weather 

 following rains the salts crystallize out on the 

 :ce of the soil, leaving either a white or a 

 black deposit. White alkali consists mainly 

 of sodium chloride and sodium sulphate and is 

 ri chemically neutral. Black alkali usually 

 contains sodium carbonate and is really alka- 

 Ine in the chemical sense of the word. The 

 Muck or brown color is due to the action of 

 the sodium carbonate on the organic matter 

 of the soil. Black alkali is the worst kind. 

 Plants can stand about one-fourth of one per 

 cent of sodium chloride or one-half of one per 

 cent of sodium sulphate, but few of them will 

 grow in soil containing one-tenth of one per 

 cent of sodium carbonate. Black alkali soils 

 are benefited by the application of land plaster 

 (gypsum, calcium sulphate), which converts 

 the sodium carbonate into the less harmful 



202 ALLAH 



sodium sulphate and the harmless or bene- 

 ficial calcium carbonate. Too heavy irrigation 

 brings up the soluble salts from the subsoil 

 and so makes alkali soils worse. Sometimes it 

 converts good soil into alkali land. Irrigation 

 of hillsides often causes alkali trouble in the 

 vallrys, because the salts washed out of the 

 highlands accumulate in the lowlands. The 

 only remedy for alkali in soils is to remove the 

 salts by drainage. 



Alkali soils are common in dry climates. 

 They occur in many places in the western part 

 of the United States. J.F.S. 



ALKALOIDS, al' kaloyds, a class of chemi- 

 cal compounds which includes the strongest 

 poisons and the most powerful remedies known 

 to man. Their names usually end in ine, as 

 atropine, caffeine, cocaine, morphine, quinine 

 and strychnine, all of which are described in 

 these volumes. An alkaloid, like an alkali, 

 will combine with an acid to form a salt. It 

 is, therefore, a base (which see). An alkali, 

 however, is mineral, or inorganic, whereas an 

 alkaloid is vegetable, or organic. An alkaloid 

 may be defined as an organic base, but the 

 term is usually restricted to the vegetable 

 world, the term for animal alkaloids being 

 ptomaine (which see). Most alkaloids are 

 odorless, crystalline bodies, more soluble in 

 alcohol than in water, but a few, such as nico- 

 tine, are liquid and mixible with water; the 

 solids contain oxygen in addition to carbon, 

 hydrogen and nitrogen, which are present in 

 all forms. Nearly all alkaloids, if taken in 

 harmful doses, injure the nervous system. 

 They frequently cause permanent paralysis of 

 certain nerves and may even cause death. The 

 possible dangers from their use make it advis- 

 able never to use them except on the prescrip- 

 tion of a physician. 



Alkaloids are found in many plants, usually 

 combined with organic acids. They often occur 

 in the fruits and seeds, but sometimes in the 

 roots and bark. Opium (which see), a product 

 of the unripe fruit of the poppy, contains a 

 score of different alkaloids, of which morphine 

 is the most abundant; the roots of the various 

 species of aconite (which see) yield a dozen or 

 more; coca leaves give cocaine and several 

 others; and the barks of cinchona plants yield 

 a group of over thirty, among them quinine 

 and cinchonine. Coffee berries and tea leaves 

 contain caffeine, cacao (cocoa) beans theobro- 

 mine, and tobacco leaves nicotine. J.F.S. 



ALLAH, al' la,- the Arabic name for the Su- 

 preme Being, corresponding to the Hebrew 



