8 BULLETIN 123, U. S. DEPARTMENT OF AGRICULTURE. 



Weigh a potato ; bake it, and weigh again after baking ; put in the oven and 

 allow it to turn to charcoal, and weigh again ; then burn the charcoal, weigh the 

 ash, and compare the result with the original weight of the potato. 



Fat. — Crush nuts, ripe olives, or mustard seeds on blotting paper. 



Put some peanut butter in a piece of cheesecloth and leave in the oven or in 

 a water bottle until the oil separates. 



If an equal volume of ether is added to ground flaxseed or peanuts and 

 allowed to stand 10 minutes or more the fat will be dissolved in the ether. 

 The liquid may then be filtered and left in a draft of air until the ether evapo- 

 rates and the fat remains. The ether must be very carefully used as it is 

 very volatile and inflammable. Do not use it near a fire or lighted lamp. 



Protein. — Soak split peas for 24 hours or more, then heat in the same water. 

 Skim the white froth and test that and some of the water with dilute nitric 

 acid. The protein present becomes yellow when the nitric acid is added and 

 the whole is heated. Treat egg white or milk in the same way for comparison. 



A still simpler though less certain test for protein is the unpleasant smell 

 given off when materials containing it are burned. Burned milk or eggs have a 

 well-known odor, protein-rich seeds, such as beans or peas, burn with much the 

 same smell. 



Starch. — Grind peas or beans in a mortar or grate a potato or two, spread the 

 ground material on a fine wire strainer or on a piece of coarse cloth, and pour 

 water through a number of times. This will wash the starch through the 

 strainer or cloth and it will settle in the water. Note that very little starch 

 dissolves in cold water and that most of it settles. A drop of dilute iodin on 

 raw starch gives a blue color. After starch is thoroughly cooked the blue color 

 will not appear when iodin is added. (See also experiments under Lesson V, 

 p. 30.) 



Sugar. — Boil down the water in which carrots, beets, or squash have been 

 boiled until it is a thick sirup ; then test by tasting. 



Evaporate further until it burns and compare the odor with that from burn- 

 ing sugar. 



GERMINATION TESTS WITH SEEDS AND BOOTS. 



Have some squash seeds soaked for 24 hours or longer. Split some open and 

 find the seed leaves or embryo plant. Plant others and examine one or more 

 each succeeding lesson, noting the differences as the embryo develops. 



Try similar experiments with other large seeds, like peas, or kidney or Lima 

 beans. 



In the same manner experiment with sprouting potatoes or onions. After 

 these have each been weighed and the weight recorded they may be put in 

 earth or in a glass of water, or even wrapped in moist cloth or paper. Keep 

 some away from the light and others in bright sunshine. Notice the changes 

 from day to day and the gradual shrinking of the tuber or bulb as the sprouts 

 develop; estimate loss of substance by appearance and by weighing the bulb 

 or tuber (first cutting off the top or the sprouts) and comparing this with the 

 original weight. 



Cut the green top from a carrot ; put the cut surface down in a glass of 

 water, and place in the sunlight ; in a few days small leaves will appear. 



Chop raw spinach fine, press in a cloth, then heat the juice extracted. Dip 

 or strain the extract from the water and combine with sugar to preserve it. 

 The green coloring matter thus obtained may be reserved for tinting candies 

 and ice cream. If cooked too long it loses its vivid green. 



