128 Lessons in Nature Study. 



will turn it olue. Ask children to bring things and test 

 them for starch. Is there starch in bread, cake, flour, corn 

 meal, oatmeal, powdered sugar, etc. 



A small drop may be placed on each child's hand, to 

 show that iodine stains the skin, etc. 



I have always found iodine a very interesting substance 

 with children. 



V. Lime. 



Bring in a piece of the size of a hen's egg. (It is not well 

 to let the children handle this, as it cauterizes the skin.) 

 Place it in a chalk-box and dash a little water upon it. See 

 it swell and crack open. See the steam rise from it. After 

 a little pou-r on some more water cautiously, and do not 

 permit the children to stand too near, as it sometimes flies 

 and might burn. See it crumble. The lime is very thirsty. 

 We give it water to slake its thirst. We say we " slake the 

 lime." When it stops hissing, it will be " slaked lime." 



Now we will put the slaked lime into a pail of water and 

 stir it. What have we now? Whitewash (milk of lime) 

 We will let it settle. See how clear the water on top is now. 

 This will furnish a supply of limewater of use when car- 

 bonic acid in the breath is studied. Thus we make the 

 work of one class help in the preparation of work for 

 another. 



VI. Glass. 



A supply of all kinds of glass should be provided ; at 

 least the following should be at hand : window-glass, 

 American plate, French plate, green bottle-glass, yellow 

 bottle-glass, glass marbles, stained glass, and fragments of 

 colored glass. Broken bottles, glassware, sets of cheap 

 jewelry, broken lamp-shades, etc., etc., all furnish the very 

 material needed. When possible, a fragment from some 

 glass-works and pieces of slag from iron-works are useful. 

 The teacher should also have a piece of soft glass tubing at 

 least three inches long. 



