THE IRKIGATION AGE. 



13 



\vhite spots; The wind carries it everywhere, and it 

 takes root wherever it happens to fall. It can only 

 be gathered early in the morning as it soon decomposes, 

 or corrupts. The natives gather it from the ground 

 in large quantities and make it into bread. This is 

 said to be what constituted the "rain of manna" which 

 fed the Israelites during their wanderings in the des- 

 ert, and it derives its name from that circumstance. 



Manna sugar is found in the juice of the larch 

 tree and in the common garden celery. In the mush- 

 room a colorless variety is found. To add two other 

 varieties of sugar, the black sugar of liquorice root 

 and sugar of milk may be mentioned. 



GLUCOSE. 



The name of this sugar means "sweet," a sweet 

 principle, or element. It occurs in nature very abun- 

 dantly, as in ripe grapes, and in honey, and it is manu- 

 factured in large quantities from starch by the action 

 of heat and acids. It is only about one-half as sweet 

 as cane sugar. It is sometimes called "dextrose," 

 "grape sugar," and "starch sugar." What is known 

 to the trade as "glucose," is the uncrystallizable resi- 

 due in the manufacture of glucose proper, and it con- 

 tains some dextrose, maltose, dextrine, etc. Its pro- 

 fusion and ease of manufacture makes it a cheap adul- 

 teration for syrups, in beers, and in all forms of cheap 

 candies. The test for it is the same as that given to 

 distinguish between cane and grape sugar. 



All the elements in the foregoing sugars are simi- 

 lar in their chemical constitution, and what is still 

 more remarkable about them, is the fact that they 

 may be transformed one into the other, that is : Woody 

 fiber may be changed into starch by heat, sulphuric 

 ncid, or caustic potash ; the starch thus produced may 

 be further transformed, first, into gum, and then into 

 grape sugar by the prolonged action of dilute sulphuric 

 acid and moderate heat. When cane sugar is digested 

 (heated) with dilute sulphuric acid, tartaric acid (acid 

 of grapes), and other vegetable acids, it is rapidly con- 

 verted into grape sugar. When sugar occurs in the 

 juice of any plant or fruit, in connection with an acid, 

 it is always grape sugar, because cane sugar can not 

 exist in combination with an acid, but is gradually 

 transformed into grape sugar. This is the reason why 

 fruits ferment so readily, and why, even when pre- 

 served with cane sugar, the latter is slowly changed into 

 grape sugar and then fermentation ensues, and the 

 preserved fruit "spoils." 



GLUTEN, VEGETABLE ALBUMEN AND DIASTASE. 



These substances are the nitrogenous elements in 

 plants. 



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 sub- 

 stance to pass off. The percentage of gluten in various 

 grains is as follows : 



Wheat 8 to 35 per centum. 



Rye 9 to 13 per centum. 



Barley 3 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 substances resembling 



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

 readily 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 vine- 

 gar, 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 



Rye 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 re- 

 lated to each other as sugar and starch. They con- 

 sist of the same elements united together in the same 

 proportions, and are capable of similar mutual trans- 

 formations. The following table will show the per- 

 centages 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 disagree- 

 ble odor, giving off, among other compounds, ammonia 

 and vinegar. 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 manu- 

 factured 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 ex- 

 panded, and then it disappears. Its functions, there- 

 fore, 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 ad- 

 hesive paste, and then converts it into grape sugar. 

 Now, the starch in the seed is the food of the future 

 germ, prepared and ready to minister to its wants when- 

 over heat and moisture come together to awaken it into 

 life. But starch is insoluble in water and could not, 

 therefore, accompany the fluid sap when it begins to cir- 

 culate. 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 

 ;t to the point of growth. When the little plant is able 

 to provide for itself, and select its own food out of the 

 foil and air, it becomes independent of the diastase and 

 the latter is no longer wanted. Weaning a child will 

 give the reader the idea. 



