9*2 NATURE TEACHING. 



lime-water and shake gently : the lime-water 

 will become cloudy owing to the formation 

 of carbonate of lime (chalk) by the union of 

 the lime with the carbon dioxide produced 

 by the charcoal burning in the oxygen of 

 the air. 



4. Pour a little lime- water into a tumbler 

 or small glass, and by means of a tube (of glass, 

 bamboo or a grass stalk) pass the breath from 

 the lungs through the lime-water, which will 

 soon become cloudy from the formation of 

 carbonate of lime as in the last experiment. 

 If the breathing is continued for a long time 

 the lime-water will become clear again owing 

 to the chalk being dissolved in the excess of 

 carbon dioxide. 



5. Into a similar bottle, corked or covered 

 with a piece of glass, place about a hand- full 

 of the young tips of leafy shoots, or opening 

 flower-buds, for instance marigolds. Add a 

 very little water to keep them moist, and put 

 away in the dark for about six hours. Test as 

 before with lime-water, when it should be 

 found that once again we have had carbon 

 dioxide produced in considerable amount. Re- 

 peat the experiment with similar leafy shoots 

 but, instead of placing them in the dark, keep 

 them in a strong light in a window. No 



