CHAPTER VI 



HOW JACK'S HOUSE EXTRACTS ITS BUILDING MATERIALS 

 DIGESTION 



WE want to learn a great deal about the foods 

 used in building Jack's house. First, however, as 

 a help in forming correct ideas, let us see how foods 

 are changed in our bodies to a form that can be carried 

 to every part, and made use of where needed for 

 repairs and additions. Compare a piece of bread with 

 a few drops of blood, and notice how different they are 

 in appearance. How strange it is that bread and other 

 solid foods we eat are changed to a form in which 

 they may be taken into the blood ! To understand 

 this marvellous process, we must know something 

 about chemistry. "Chemistry !" grammar school girls 

 and boys may exclaim: "Why that is one of the 

 difficult subjects in the high school ! How can you 

 expect us to know anything about Chemistry?" 



Although Chemistry is a high school subject, it 

 has to do with many common things with which all 

 are familiar. The dictionary tells us that Chemistry 

 is the science which treats of the composition of 

 substances and the changes in the composition and 



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