SOAP MAKING 189 



Soap is a combination of grease and lye. Caustic 

 potash and grease make soft soap, while caustic soda and 

 grease make hard soap. The kind of grease which is 

 used makes the soap high grade or low grade ; toilet soap 

 or laundry soap. 



Experiment 78. Soap Making. 



Apparatus: Burner, ring stand, tin can. 



Materials: Lard, sodium hydroxide (caustic soda), 

 salt. 



To 85 cubic centimeters of water in the tin can add 

 15 grams of sodium hydroxide and 40 grams of lard; boil 

 slowly ten minutes. Be very careful that the mixture 

 does not spatter upon you. After boiling add about 25 

 grams of salt and continue to boil for five minutes. Then 

 allow all to cool and remove the soap which will be on 

 top. Let the cake dry for several days, and then see if 

 it will produce suds. 



78. Bread Making. 



There are several kinds of bread but they can all be 

 placed in two classes bread raised by baking soda and 

 bread raised by yeast. In all cases the bubbles are 

 formed by carbon dioxide. In Experiment 48, (d), we 

 saw that baking soda and cream of tartar, when mixed in 

 solution, produce carbon dioxide. The cream of tartar 

 should be mixed dry with the flour, and the baking soda 

 dissolved in a little water, if they are to accomplish the 

 most good. Why? In Experiment 63 it was shown 

 that baking soda, when added to sour milk, makes it 

 sweet. At the same time carbon dioxide is produced by 

 the action of the acid in the milk upon the baking soda. 



