32 APPLIED PHYSIOLOGY 



12. Burn some bread or meat and save the ashes. The ashes 

 represent the mineral part of food, and consist mainly of lime, salt, 

 soda, potash, and iron. 



13. Show diffusion by tying a piece of parchment over the end of a 

 large glass tube. Fill the tube with salt and water and immerse it in 

 ajar of fresh water. In a little while the liquid will rise in the tube,, 

 while the water in the jar will begin to taste salt. The process will 

 continue until the water in the tube and in the jar are of equal saltness. 

 If the water in the jar were renewed, all the salt could be extracted 

 from the tube. 



14. Show the affinity between acids and alkalies by dropping soda 

 in vinegar. Notice that the mixture boils and foams, and both sub- 

 stances become changed. Drop some soda in water and it simply 

 dissolves and forms a solution. 



15. Drop a pinch of baking soda in a small cup of water. Then 

 stir in some dilute hydrochloric acid, drop by drop, until the mixture 

 ceases to bubble. Taste the mixture and notice that it is salt. Ex- 

 plain that the hydrochloric acid and the soda have formed a chemical 

 combination and each has neutralized the other. The new substa'nce 

 formed is chloride of sodium or common salt. 



REVIEW TOPICS 



1. Define and name the proximate principles. 



2. Describe water and define a solution. 



3. Describe albumin. 



4. Describe diffusion. 



5. Describe putrefaction. 



6. Describe nucleo-albumin, and its relation to iron. 



7. Describe fats and oils. 



8. Describe an emulsion. 



9. Describe saponification. 



10. Describe starch, sugar, and wood. 



11. Describe salt. 



12. Describe lime. 



13. Describe the alkalies. 



14. Define chemical action and chemical affinity* 



15. Name some chemical actions in the body. 



