Baking powder

a raising agent used in making biscuits, breads and particularly cakes. It consists of bicarbonate of soda (alkaline), cream of tartar (tartaric acid) with a dried starch or flour. You can make your own by combining 15ml (1 tbsp) bicarbonate of soda with 30ml (2 tbsp) cream of tartar. Always measure carefully as too much or too little can upset the balance of the recipe and spoil the flavour.