Water is a valuable medium for cooking. As it heats, small bubbles are formed, which continually increase in number and size, but gradually disappear. Some time before the boiling-point is reached, an occasional large bubble will rise to the surface and disappear. The water has then reached the simmering-point, 185 deg., a temperature frequently made use of in cooking. When many bubbles form and break, causing a commotion on the surface of the water, the boiling-point, 212 deg., has been reached. _Mineral matter._--Mineral matter is a second food-stuff that is needed by the body, but the amount required is very small. If a variety of food is used, there is generally sufficient mineral matter in the diet. Fruits and vegetables, especially fresh green vegetables, are comparatively rich in mineral matter. Mineral matter builds up the bones and certain tissues, such as the hair, teeth, and nails, and regulates the body processes by keeping the blood and digestive fluids in proper condition. _Green vegetables._--Green vegetables hold an important place in the diet, because they contain valuable mineral matter. They also contain a high percentage of water and considerable cellulose. With few exceptions they should be eaten raw, because the mineral salts, being soluble, are lost in the water in which they are cooked and because the cellulose serves its purpose best in the crisp form. Cabbage is rendered much more difficult of digestion by cooking. Spinach, beet tops, etc., are more palatable when cooked. The delicately flavoured vegetables should be boiled in a very small amount of water, so that they need not be drained. Thus the mineral matter will be retained when the vegetables are served. PRELIMINARY PLAN There should be provided for the lesson (from the homes of the pupils or the school garden), some fresh vegetables in season; one that can be cooked by boiling and one that can be served uncooked with a simple dressing. One of the pupils should write the recipes on the black-board before the lesson hour. RECIPES _Preparation of Fresh Green Vegetables_[A] Wash the vegetables thoroughly, leaving them in cold water to crisp, if wilted. Keep cool until ready to serve, then arrange daintily, and dress with salt, vinegar, and oil as desired, or prepare a dressing as follows: _Cooked Dressing_ 1/2 tbsp. salt 1 tsp. mustard 1-1/2 tbsp. sugar A few grains pepper 1/2 tbsp. flour 1 egg or yolks of 2 eggs 1-1/2 tbsp. melted butter 3/4 c. milk 1/4 c. vinegar Mix the dry ingredients, add the egg slightly beaten and the butter and the milk. Cook over boiling water until the mixture thickens. Add the vinegar, stirring constantly. Strain and cool. Note.[A]--It may be well to omit from this lesson the uncooked vegetable that is served in the form of a salad and to give it at some other time. It is not well to attempt to teach more than the pupils can master thoroughly.