10 



AGRICULTURE. 



(CaCl,), water (H^O),and tlie gas carbon dioxide (COJ 

 are formed. 



{c) Now pass some of this gas, or carbon dioxide, from 

 the bottle into the solution of clear lime-water (Fig. 3). 



{d) To prepare lime-water, dissolve common lime in 

 pure water, let stand until clear, and carefully pour off 

 the liquid, or pass it through a filter-paper. J What 

 takes place when the carbon dioxide passes into the 

 lime water? Allow the gas to continue to pass, and 

 note the result. 



(e) Boil the liquid, and again note result. 



(/) Write up this experiment, stating the materials 

 used, observations made, and what the experiment 

 teaches, together with any further remarks or conclu- 

 sions you may make concerning each step. 



When the carbon dioxide was first passed into 

 the lime-water, a precipitate of calcium carbon- 

 ate ( CaCO,), or limestone, 

 was formed. 



It continued to pass 

 until there was no more 

 calcium hydroxide, or lime- 

 water, CafOH),, to com- 

 bine with it, when the 

 ^ carbon dioxide united with 

 the water (H3O) to form 

 carbonic acid ( H,CO,). 

 This acid at once acted 

 upon the precipitate of calcium carbonate, form- 

 inof a soluble bicarbonate of calcium, H^Ca 

 (CO3),, which is dissolved, and the liquid be- 

 comes clear. The boiling drives out part of 



FIG. 3. — APPARATUS FOR 

 EXrERIMENT I. 



