GENERAL SCIENCE 



potato, and raw flour and bread well baked. This 

 dextrin sugar, formed in the bread while baking, is turned 

 into caramel on the surface of the loaf, where the tempera- 

 ture is very high, and gives to the bread crust the brown 

 color. Caramel is also formed when bread is toasted. 



Bread made from corn meal is not porous or full of 

 small holes like bread made from wheat flour. Wheat 

 flour has in it a form of albumin called gluten. This 



gluten when moistened is very 

 tough and gummy and does 

 not permit the gases formed in 

 the dough to escape. The gas 

 formed in the dough raises it. 

 When the dough is placed in 

 the oven, the gas in it expands 

 because of the intense heat and 

 so raises the dough still more, 

 so that the heat can affect the starch and albumin in all 

 parts of the loaf, that is, bake it clear through. There 

 are several ways of forming this gas in the dough; these 

 may be classed as follows: i. By the use of chemicals. 

 2. By the use of a one-celled plant (yeast). 3. By a me- 

 chanical method such as is sometimes used in baking 

 cakes, viz. beating the dough violently to get air mixed 

 with it, which will expand when the dough is placed in 

 the oven, and thus raise it. 



19. Baking Soda (NaHC0 3 ). Baking soda is also 

 known as bicarbonate of soda and sodium hydrogen car- 

 bonate. It is a salt, slightly basic in its reactions on other 

 compounds. When it is acted on by an acid, such as 

 sour milk, carbon dioxide is set free. If it is mixed with 

 the dough without the use of a mild acid, the carbon 

 dioxide will be liberated by the action of the heat while 



'Gluten Cells 



A GRAIN OF WHEAT 



Showing starch and gluten. 

 (Magnified.) 



