THE IRRIGATION AGE. 



049 



Gluten is a soft, tenacious and elastic substance, which 

 can be drawn out into long strings. It has little color, 

 taste, or smell, and is scarcely diminished in bulk by 

 washing either in hot or cold water. It is a product of 

 grain flour, left after washing dough in a fine sieve, and 

 allowing the milky, soluble substance to pass off. 

 percentage of gluten in various grains is as follows: 



\Vhcat 8 to 35 per centum. 



R ye 9 to 13 per centum. 



Barley .-! to 6 per centum. 



Oats 2 to 5 per centum. 



Dried in the air it diminishes in bulk, and hardens 

 into a brittle, transparent yellow substance resembling 

 corn, or glue. It is insoluble in water, but dissolves read- 

 ily in vinegar, alcohol, and in solutions of caustic potash, 

 or common soda. 



Vegetable albumen is practically the same as the 

 white of eggs. It has neither color, taste, nor smell, is 

 insoluble in water or alcohol, but dissolves in vinegar, 

 and in caustic potash, and soda When dry it is brittle 

 and opaque. It is found in the seeds of plants in small 

 quantities, and in grain in the following percentages: 



Wheat 75 to 1.50 



R ye 2.0 to 3.75 



Barley 10 to - 50 



Oats 20 to - 50 



It occurs largely, moreover, in the fresh juices of 

 plants, in cabbage leaves, turnips and numerous others. 

 When these juices are heated, the albumen coagulates 

 and is readily separated. 



Gluten and vegetable albumen are as closely related 

 to each other as sugar and starch They consist of the 

 same elements united in the same proportions, and are 

 capable of similar mutual transformations. The follow- 

 ing table will show the percentages in which the reader 

 will notice that nitrogen is an element which does not 

 exist in starch or sugar: 



Carbon 54.76 



Oxygen 20 - 06 



Hydrogen : 7.06 



Nitrogen 18.12 



When exposed to the air in a moist state both these 

 substances decompose and emit a very disagreeable odor, 

 giving off, among other compounds, ammonia and vine- 

 gar. Both of them exercise an important influence over 

 the nourishing properties of the different kinds of foods, 

 as we shall see in a subsequent chapter. 



Diastase. 



This substance may be manufactured from newly 

 malted barley, or from any grain or tuber when ger- 

 minated. It is not found in the seed, but is manufactured 

 during the process of germination by the seed itself, or 

 its decomposition, and it remains with the seed until the 

 first true leaves of the plant have expanded, and then it 

 disappears. Its functions, therefore, are to aid in the 

 sprouting of the seed, and that accomplished, and there 

 being no further use for it, it disappears The reason for 

 this is as follows: 



Diastase possesses the power of converting starch 

 into grape sugar. First, it forms out of starch a gummy 

 substance known as dextrine, in common use as adhesive 

 paste, and then converts it into grape sugar. Now, the 

 starch in the seed is the food of the future germ, pre- 

 pared and ready to minister to its wants whenever heat 

 and moisture come together to awaken it into life. But 

 starch is insoluble in water and could not, therefore, ac- 

 company the fluid sap when it begins to circulate. For 

 which reason, nature forms diastase at the point when the 

 germ first issues, or sprouts from its bed of food. There 

 it transforms the starch into soluble sugar, so that the 

 young vessels can take it up and carry it to the point of 

 growth. When the little plant is able to provide for itself, 

 and select its own food out of the soil and air, it becomes 

 independent of the diastase and the latter is no longer 

 wanted. Weaning a child will give the reader the idea. 



Vegetable Acids. 

 There is another class of compound substances which 



play an important part in the development of plant foods 

 and the perfection of growth. They are known as the 

 vegetable acids, and it is due to them that plants possess 

 a taste and flavor, every plant having its own peculiar 

 acid. They are usually classified into five species and 

 enter into combination with all of the substances here- 

 tofore referred to. The}' are: 



Acetic acid (vinegar), tartaric acid (acid of wine), 

 citric acid (acid of lemons), malic acid (acid of apples), 

 and oxalic acid (acid of sorrel). Acetic acid is the most 

 extensively diffused and the most largely produced of all 

 the organic acids. It is formed wherever there is a 

 natural or artificial fermentation of vegetable substances. 

 It easily dissolves lime, magnesia, alumina, and other 

 mineral substances, forming salts known as "acetate," 

 which are all soluble in water, and may, therefore, be 

 absorbed by the root pores of plants. It is an acid com- 

 mon in everything, and may be manufactured from wood, 

 alcohol, cane sugar and from the juice of apples, or by 

 any vegetable fermentation, the process of fermentation 

 throwing off carbonic acid and forming vinegar. 



Tartaric acid finds lodgment in a variety of plants. 

 The grape and the tamarind owe their sourness to it, and 

 it exists also in the mulberry, berries of the sumach, in 

 the sorrels, and in the roots of the dandelion. It is de- 

 posited on the sides of wine vats, and when purified and 

 compounded with potash, it becomes the familiar "cream 

 of tartar," which is known to every housewife. In the 

 grape it is converted into sugar during the ripening of 

 the fruit. 



Citric acid gives sourness to the lemon, lime, orange, 

 grape fruit, shaddock and other members of the citrus 

 family. It is the acid in the cranberry, and in numerous 

 small fruits such as the huckleberry, wild cherry, cur- 

 rant, gooseberry, strawberry, and the fruit of the hawthorn 

 In combination with lime, it exists in the tubers, and with 

 potash, it is found in the Jerusalem artichoke 



Malic acid is the chief acid in apples, peaches, plums, 

 pears, elderberries, the fruit of the mountain ash. It is 

 combined with citric acid in the small fruits above men- 

 tioned, and in the grape and American agave it is asso- 

 ciated with tartaric acid. It has exactly the same chemical 

 constitution as citric acid, and the two bear the same 

 relation to each other as starch, gum and sugar. They 

 undergo numerous transformations in the interior of plants, 

 and are the cause of the various flavors possessed by 

 fruit and vegetables. 



Oxalic acid has poisonous qualities, but an agreeable 

 taste. It occurs in combination with potash in the sorrels, 

 in garden rhubarb, and in the juices of many lichens, or 

 mosses. Those mosses which cover the sides of rocks 

 r.nd the trunks of trees sometimes contain half their 

 weight of this acid in combination with lime. 



This chapter is, of course, one step farther in advance 

 of the one immediately preceding, and the facts stated 

 are intended to lead on up to a complete, practical know- 

 ledge of the forces of nature operating in the soil and 

 within the plant to altain perfection. Nothing but the 

 ijare essentials, the mere outlines, have been given so far; 

 to attempt to enter into all the deta'ls would be to write 

 an entire volume, the reading of which might prove tire- 

 some and unproductive of anything practical. All that it 

 is desired to do in these preliminary chapters is to furnish 

 the reader with sufficient elementary knowledge to enable 

 him to go farther on his own account and to infer what 

 the soil needs for the cultivation of plants; how that soil 

 is to be cultivated, and how the element of water is to be 

 applied to it in order to increase its productiveness and 

 his profit. This is the true preliminary to irrigation, as we 

 imagine, for it would convey no information to suggest the 

 pouring of water on the oil, and drenching plants and 

 crops with it, unless the intelligence is prepared to un- 

 derstand why that should be done, and all the details and 

 consequences laid before the reason and common sense. 



So far, the reader ought to have a comparatively clear 

 idea of the chemical constitutions of the substances which 

 enter into the soil, and from the soil into the plants, but there 

 still remains the question : How do the substances necessary 

 to plant life get into the condition of pjant food? This ques- 

 tion will be answered in a future article. 



