The Story-Book of the Fields 



a funnel we filter it through filtering paper. 

 A colourless and perfectly limpid liquid passes 

 through the filter. This is water containing 

 a small quantity of lime in solution. It is 

 called lime-water. This is all the preparation 

 necessary to enable us to detect the carbonic 

 acid gas. 



Now we must procure a large glass bottle 

 with a wide mouth. An ordinary decanter 

 will do, if the mouth is large enough. To 

 begin with the bottle is full of air and con- 

 tains nothing else. We pour in a little lime- 

 water and shake it so that the lime-water may 

 reach every part of the bottle. Nothing 

 happens. The lime-water was clear at its 

 entrance and remains clear. We conclude 

 that the air has no effect on the lime-water. 



Let us try again. We introduced into the 

 bottle a lump of burning coal hanging by a 

 wire. For a time this coal burns, then it turns 

 paler, and ends by going out. We take it 

 out. What has happened ? Evidently, from 

 the fact of combustion, some carbon has been 

 dissolved in the air of the bottle, which must 

 now contain carbonic acid gas. 



Let us again pour in a few drops of lime- 

 water and shake it. Now the liquid, which 

 was originally perfectly clear, is disturbed, 



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