Fermentation, Distillation, etc. 121 



It is working or fermenting. I will write this new word 

 on the board. Does fruit always ferment ? " When the air 

 gets into a can of fruit, it always ferments." Some day we 

 shall learn why fruit ferments. 



Did you ever see mamma bring up a can of fruit from 

 the cellar when it was working ? " My mamma scalds hers 

 when she finds it working." 



Now we will catch some of this gas coming from the fer- 

 menting fruit and see what we can do with it. We will first 

 bend a glass tube, and then bore a hole through this cork 

 with a small file and fit the tube in. We will put the 

 cork in tight so that the gas will come out through the 

 tube, T. Let us take this glass of limewater, W, and let 

 the glass tube dip into it. Watch it carefully. " I see a 

 bubble of gas come from the tube." " When you shake the 

 bottle, more gas comes through the tube and bubbles 

 through the limewater." " The limewater is turning white." 

 " It is looking like milk." 



Yes, this proves that the gas is not air, but carbonic-acid 

 gas. This gas comes off from all things that are rotting. I 

 will now take the cork from the bottle and you may see 

 what I do. Harry may scratch a match here and dip it 

 into the mouth of the bottle. See what happens. " The 

 match went out." Here are several matches. Each one 

 may scratch one and dip it in this gas. " They go out." 

 " The gas puts them out." 



This gas puts out fire and turns limewater milky white. 

 If little boys and girls were to breathe it, it would kill them. 

 Carbonic acid is very poisonous. Now write on your slates 

 what you have learned this morning about carbonic acid. 

 Some other day we will learn more of this dreadful gas. 



III. DISTILLATION. 



Yesterday we saw how when an apple rots or ferments 

 it gives off what gas ? Will this carbonic-acid gas burn ? 

 Will a stick burn in it ? Could a little boy live in it ? What 

 does this gas do when it bubbles through limewater ? 



