26 



GENERAL SCIENCE 



while they are dry. If water is mixed with the powders, 

 a reaction will occur during which all the carbon dioxide 

 will escape. For this reason baking powder should 

 be thoroughly mixed with the dry flour before making 

 the dough, then the carbon dioxide will not be formed so 

 rapidly and will not escape. Self-rising flour has baking 

 powder mixed with it. 



How to test baking powders for alum. Burn two or 

 three grams of the powder in a porcelain dish. Mix the 



ash left in the 

 dish with boiling 

 water and filter. 

 Add to the fil- 

 trate (the filtered 

 solution) enough 

 ammonium chlo- 

 ride solution so 

 the mixture will 

 have a distinct 

 odor of ammonia. 



Look for white flakes in the solution. If none appear 

 immediately, warm the solution slowly. These white 

 flakes, if any, are composed of an alum compound and 

 indicate the presence of alum in the baking powder. 



21. Baking soda and baking powders are used only 

 when not much time is taken and in baking in small 

 quantities such foods as cakes, pies, biscuits, and corn 

 bread. They are used in making corn bread because 

 corn meal does not have any albumin in the form called 

 gluten to hold the carbon dioxide set free by the slow 

 action of yeast. The corn bread must be baked as soon 

 as the mixture is made. 



There are several reasons why baking powder is not 



FUNNELS FOR FILTERING 

 Three ways of supporting them. 



