USES OF CARBON DIOXIDE IN COOKING 



235 



Sodium aluminum sulphate is sometimes used in the place of 

 burnt alum. 



NaHCOa 



Baking soda 



NaHCO 3 



Baking soda 



6NaHCO 3 



2NaHCO 3 



FORMULAS FOR FORMING CO 2 IN BREAD 



+ C 2 H 6 O.COOH = C 2 H 5 O.COONa-f H 2 O + CO ? 



+ Lactic acid = Sodium lactate + Water +Carbon dioxide 



+ HKC 4 H 4 O 6 =KNaC 4 H 4 O 6 



-{-Cream of tartar = Rochelle salts 



+K 2 A1 2 (S0 4 ) 4 



Burnt alum 



+ H 4 Ca(r0 4 ) 2 



Calcium acid 

 phosphate 



= A1 2 (OH) 6 



= Aluminum 



hydroxide 



+K 2 S0 4 



+ H 2 + C0 2 



-|-3Na 2 SO 4 



+Glauber's salt 

 + 6CO 2 



Potassium sulphate 



= HCaPO 4 + HNa 2 PO 4 +2H 2 O +2CO 2 



Acid calcium Acid sodium 

 phosphate phosphate 



(NH 4 ) 2 NH 2 HCO 2 CO 3 



Ammonium carbonate 



3NH 3 



Ammonium gas 



2NaHCO 3 



+Heat-Na,CQi 



Neutral sodium carbonate 



+H 2 O+2CO 2 



+ H 2 + C0 2 



Test for Alum in Baking Powder and Bread. Make up a saturated solu- 

 tion of ammonium carbonate and also a tincture of logwood by digesting 

 i ounce well-powdered logwood chips in a cup of alcohol. Mix up a little bak- 

 ing powder, biscuit, cake or cooky with a little water. Add a teaspoonful of 

 logwood tincture and an equal amount' of ammonium carbonate. 



If alum is present, that 'is, if alum baking powder has been used, 

 the color changes to lavender or blue, and does not disappear on 

 boiling. If alum is not present the color varies from red to pink. 



Test for Ammonium in Bread. Mix some bread or baking powder with 

 a small amount of 16 per cent solution of sodium hydroxide. Boil the mix- 

 ture. Hold in the steam a piece of red litmus paper, and avoid touching the 

 dish or test tube. 



If ammonia is present the litmus paper will turn blue. 



Yeast in Making Bread. The use of yeast in making bread light 

 has been known from ancient times. It may have been found by 

 an accident. Wild yeast is floating in the air everywhere. If 

 dough is left exposed, some of these wild yeast plants are sure to 

 fall into it. 



