3d GENERAL SCIENCE 



how it grew, and that it could change sugar into alcohol 

 and carbon dioxide. Alcohol was known ages ago, 

 but it was not known that alcohol is a poisonous -waste- 

 product of the yeast plant. 



The yeast was studied until a way was found by which 

 it could be grown in great amounts for bread making and 

 for the production of alcohol and the various intoxicating 

 drinks containing alcohol. The commercial yeast in 

 the form 01 cakes consists of a great number of yeast 

 plants without sufficient moisture and food for growth. 

 When this commercial yeast is mixed with dough, the 

 yeast plants begin to grow and increase rapidly, giving 

 off carbon dioxide which raises the batter, and when 

 this is baked it is our modern bread. 



QUESTIONS AND EXERCISES 



1. Taste the brown crust of well-baked bread, and then the 

 white inner part. Make note of any difference. 



2. Examine the texture of wheat bread and that of corn bread. 

 Explain the difference and its causes. 



3. Dissolve some baking soda in water and observe the result. 

 Now add a few drops of vinegar. Explain what happens. What 

 made the bubbles? 



4. Dissolve some baking powder in water. Does it act the 

 same as baking soda? Why? 



5. From what you have observed, how should baking soda and 

 baking powder be put into the baking material? 



6. Why do good soda biscuits taste different from raised bread? 



7. Dissolve a teaspoonful of sugar in a gill of water and mix with 

 it a small quantity of yeast. Place it for a few hours where the 

 temperature is 70 to 95 F. Note and explain the gas bubbles. 



8. If you have a microscope, place one drop of the solution on a 

 glass slide and examine. 



