100 SCIENCE OF HOME AND COMMUNITY 



palatable. Wheat contains a sticky substance called gluten, 

 which keeps the dough porous after the gases pass through 

 it. Barley and other wheat substitutes do not contain this 

 gluten, and so it is necessary to mix a certain amount of 

 wheat with the other flours in order to furnish enough gluten 

 to make a light bread. 



LABORATORY EXERCISE 12 



Purpose. To study the action of baking powder and yeast. 



Materials. Baking powder, baking soda, cream of tartar, 

 and vinegar. 



Directions. I. Mix dry baking soda and cream of tartar. 

 Add hot water and note what happens. Add vinegar to baking 

 soda. Put a little baking powder into water and note what 

 happens. Dissolve baking soda and cream of tartar separately 

 in cold water, then pour one into the other. Try again, using 

 hot water, and note the difference. 



2. Make a paste of flour and water. Mix with this a small 

 piece of yeast cake. Allow to stand for a while in a warm place 

 and notice what happens. 



3. Put in each of two test tubes or small bottles a teaspoonful 

 of molasses and ten of water. Mix a small piece of yeast cake 

 with water and add a half to each bottle. Place one in a cool 

 place, as in an ice chest, and the other in a warm place. At 

 the end of a day notice any difference in the two. 



Methods of cooking. Water is an essential factor in cook- 

 ing. Many foods are cooked in boiling water. This in- 

 sures an even temperature as water always boils at the same 

 temperature, 212 degrees, with slight variations due to the 

 atmospheric pressure. In the double boiler the outer dish 

 holds boiling water and the inner dish the food to be cooked. 

 So long as the outer dish contains water the food will not 

 burn. Sometimes, as in stewing, foods are cooked in water 

 which is kept just below the boiling point. 



