A STUDY OF FOODS AND DIETARY 349 



animal bodies. The following is a list of the common 

 carbohydrates : 



1. Cellulose (cotton is nearly pure cellulose). 



2. Starch. 



3. Dextrin (commonly called British gum). 



4. Sucrose (cane sugar, beet sugar, maple sugar). 



5. Maltose (malt sugar). 



6. Lactose (milk sugar). 



7. Dextrose (grape sugar), j Found ^ ri ^ ^ h 



8. Levulose (fruit sugar). J 



Sucrose, maltose, lactose, dextrose, and levulose are sweet 

 and are commonly called sugars. Dextrin is also sweet. It is 

 used as an adhesive. Stamps and envelopes have dextrin as 

 an adhesive. When it is remembered that cotton is very widely 

 used in clothing, it is seen that the carbohydrates are 

 of vast importance aside from their use as food. 

 Wood contains cellulose. 



387. Simple Tests for Carbohydrates. 



Exercise 77. Tests for Carbohydrates 



1 . THE SUGARS MELT. Place half a teaspoonf ul of granu- 

 lated sugar in a large spoon and carefully heat it until it 

 melts. 



2. THE CARBOHYDRATES CHAR WHEN HEATED HOT 

 ENOUGH. Continue to heat the melted sugar until a solid J 

 black residue, carbon, is left behind. This residue contains 



most of the carbon that was in the original sugar. Repeat _ u s mg 



the charring test with starch. the pip- 



3. THE IODINE TEST FOR STARCH. Apply a drop of iodine ette. 

 solution by means of a pipette to a little starch (Fig. 245). 



What color is produced? Apply the iodine test to the inside of the 

 following grains, corn, wheat, oats; also apply it to the following 

 fruits and the vegetable, apple, banana, potato. In which ones of 

 these do you find starch? If possible compare ripe and green fruits 

 as to the presence of starch. 



388. Proteins. These substances contain nitrogen in addi- 

 tion to carbon, hydrogen, and oxygen. Many proteins also 

 contain sulphur and phosphorus. The proteins are found in 

 the cereals, in many vegetables, in meats, in milk and its 



