10 



AGRICULTURE. 



(CaClJ, water (H a O),and the gas carbon dioxide (CO,) 

 are formed. 



(<) Now pass some of this gas, or carbon dioxide, from 

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



(f/) 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. \ 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 (CaCCX), or limestone, 

 was formed. 



It continued to pass 

 until there was no more 

 calcium hydroxide, or lime- 

 water, Ca(OH),, to com- 

 bine with it, when the 

 carbon dioxide united with 

 the water (H,O) to form 

 carbonic acid (H 2 CO,). 

 This acid at once acted 



upon the precipitate of calcium carbonate, form- 

 ing a soluble bicarbonate of calcium, H 2 Ca 

 (CO 3 ) 2 , which is dissolved, and the liquid be- 

 comes clear. The boiling drives out part of 



FIG. 3. APPARATUS FOR 

 EXPERIMENT I. 



