34 



EXPERIMENTS WITH PLANTS 



substance so ttfat it no longer supports combustion. 



We may now pour a little lime-water into the jar, 

 replace the stopper and shake vigor- 

 ously. (Lime-water is prepared by 

 placing a little unslaked lime in a 

 metal dish or pail, filling the pail 

 with water and allowing it to stand 

 for a day; the water should then 

 be filtered through filter- paper or 

 through a cotton plug in the neck 

 of a funnel.) If the lime-water 

 turns milky, it indicates that the 

 oxygen has united with the carbon 



seeds produce carbon diox- / ,1 i 1 -. . 



ide. the vial is filled with ot the plant to torm carbon diox- 



li me- water. (Seen in sec- 



ide, a gas tamihar to us as soda- 

 water gas. Arrange an experiment, as shown in Fig. 

 30, by placing a vial of clear 

 lime-water surrounded by 

 soaked seeds in a jar and stop- 

 pering loosely. As a control, 

 use a similar arrangement 

 without the seeds. We may 

 make use of the fact that car- 

 bon dioxide is readily absorbed 

 by lye to perform a further ex- 

 periment. Arrange two bottles 



f . . i in , -v 31. Method of measuring the amount 



(pint Or halt-pint). aS Shown of Carbon dioxide produced by 



germinating seeds, the tumblers 



in Fig. 31, by fitting them with Sgg. n ]ye ( contro1 * the 



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