WASTE AND REPAIR FOODS 8 1 



QUESTIONS ON LESSON XIV. 



1. Define element and compound. Illustrate your answer by an experiment. 



2. Describe the general characters of the four chief elements found in the 



body. What other elementary bodies exist in the body ? 



3. Describe the chemical composition of water and air. 



4. What is meant by decay ? What are the chief products of the decay of 



organic matter ? Give the chemical composition of each. 



5. What is the difference between a nitrogenous and a non-nitrogenous 



organic compound ? Give examples of each class. 



6. Name the chief nitrogenous constituents of the body, and say where each 



may be found. 



7. Compare the chemical composition of fat, sugar, and albumen. 



8. What is the proportion of water in the body ? What is the use of this 



water ? 



9. Name the chief mineral substances of the body. Give the chemical com- 



position of each, and say where each may be found. 



LESSON XV. 

 WASTE AND REPAIR FOODS. 



THAT the body is continually wasting away may be proved as 

 follows : 



(1) Let the expired air from the lungs strike the surface of a 

 cold object, such as a looking-glass, and a deposit of water is 

 formed. Again, place the palm of the hand on the surface of a 

 very cold slate or plate of glass, and let it remain for a few 

 seconds. On removing it a similar deposit of water will be seen. 

 Thus we learn that water is continually passing off from the lungs, 

 and through the pores of the skin. Water, we remember, is 

 composed of the elements hydrogen and oxygen; hence we are 

 made acquainted with two sources of loss of these elements. 



(2) Now blow air from the lungs through a glass tube, and let 

 it bubble through clear lime-water. In a very short time the 

 lime-water assumes a milky appearance, thus proving the presence 

 of carbonic acid gas (see page 78). The lungs, therefore, are a 

 source of loss of carbon and oxygen. 



In order to ascertain the amount of loss in a given time, let a 

 person weigh himself accurately, and then, after a few hours, 

 during which time no food or drink should be taken, let him 

 weigh himself again. 



The chief sources of loss to the body are 



(i) The lungs. (2) The skin. (3) The kidneys. 



By means of the lungs we lose both water (in the form of 

 vapour) and carbonic acid gas. 



G 



