(2) Dry yeast.--The plants are put into a starchy paste and the mixture is dried. This form will keep for months, because it is perfectly dry but, for the same reason, it takes the plants a long time to become active when used. (3) Compressed yeast.--The plants are put into cakes of a starchy mixture and left moist. They will keep only a few days. Good compressed yeast is a pale fawn colour, smells sweet, breaks clean, and crumbles easily. 4. Experiments with yeast: Make a _yeast garden_ by using the plants obtained at the grocery store as follows: Take half a cup of lukewarm water to give the plants moisture, a teaspoonful of sugar for immediate food, and the same of wheat starch (flour) for a reserve food. Beat the mixture to infold oxygen, and then put in one-quarter cake of yeast plants. Divide the mixture among a number of test-tubes, so that each group of four pupils has three. (1) Place one test-tube in warm water and heat to boiling. (2) Place one test-tube in water which feels warm to the hand. (3) Place one test-tube in cracked ice and freeze the mixture. Afterwards thaw, and place the same test-tube in lukewarm water. Observe the results, and compare the amount of gas formed under the different conditions. LESSON II PRACTICAL BREAD-MAKING Ingredients of plain bread: 1. Liquid.--(1) It wets the mixture and causes the ingredients to adhere. (2) It furnishes steam for a lightening agent. (3) It allows the gluten to become sticky and elastic. (4) It furnishes moisture for yeast plants. 2. Yeast.--It gives off carbonic acid gas, which lightens the mixture. 3. Salt.--(1) It gives a flavour. (2) It retards the growth of the yeast plant. 4. Flour.--(1) It thickens the mixture. (2) It supplies food for the yeast plant. (3) It supplies gluten for a framework for the mixture. Amount of ingredients for one small loaf: Liquid--1 cup or 1/2 pt. Salt--1/2 tsp. Flour--About three times the amount of liquid Yeast--Amount depends on the time given the bread to rise, as follows: 12 hr. to rise 5 hr. to rise 3 hr. to rise 1/4 yeast cake 1/2 yeast cake 1 yeast cake NOTE.--One cake of compressed yeast contains about the same number of yeast plants as one cake of dry yeast or one cup of liquid yeast. Process in making bread: