152 BAKING POWDERS AND SODA 





The self-raising flour, so widely advertised by grocers, i 

 flour in which these ingredients, or their equivalent, have been 

 mixed by the manufacturer. 



Soda mints. Bicarbonate of soda is the main ingredient 

 of the soda mints sold for indigestion. These correct 

 tendency to sour stomach because they counteract the surplus 

 acid in the stomach, and form with it a safe neutral substance. 



Seidlitz powder is a simple remedy consisting of two pow- 

 ders, one containing bicarbonate of soda, and the other, some 

 acid, such as cream of tartar. When these substances are 

 dissolved in water and mixed, effervescence occurs, carbon 

 dioxide escapes, and a solution of Rochelle salt remains. 



Source of soda. An enormous quantity of sodium car- 

 bonate, or soda, as it is usually called, is needed in the manufac- 

 ture of glass, soap, bleaching powders, and other commercial 

 products. Formerly, the supply of soda was very limited 

 because man was dependent upon natural deposits and upon 

 the ashes of sea plants for it. Common salt, sodium chloride, 

 is abundant, and in 1775 a prize was offered to any one who 

 would find a way to obtain soda from salt. As a result of this 

 offer, soda was soon manufactured from common salt. In the 

 most recent method of manufacture, salt water, ammonia, and , 

 carbon dioxide are made to react, and baking soda is formed 

 from the reaction. The baking soda is then heated and de- 

 composes into washing soda, or the soda of commerce. 



