GASES 153 



water makes a white substance in the water, thus giving 

 a milky appearance. The substance formed is carbonate of lime. 



One of the children can breathe air thru a small amount 

 of lime water in a test-tube or other glass vessel. The lime water 

 turns white, thus proving the presence of carbonic acid. 



A bit of a candle is placed in the bottom of a glass tumbler, 

 which is covered with a book. The candle soon goes out. Test 

 the gas left with lime water. 



An inverted glass is held over the chimney of a burning 

 lamp. Slip a card over the mouth, and test the carbonic acid. 

 The gas coming from various burning substances may be tested- 



To make carbonic acid in a quantity unmixed with air, etc., 

 pound up into small pieces limestone or marble; place in a wide- 

 mouthed bottle or flask, into which is fitted a cork and delivery 

 tube. Cover the marble with water, then pour in some muriatic 

 or sulphuric acid. Bubbles of carbonic acid come off rapidly. 

 As it is heavier than air of the same temperature, it can be caught 

 in empty jars or bottles standing upright, lightly covered with 

 cards. When a few jars have been obtained, try them with lime 

 water, lighted candles, lighted splinters, etc. Show that the gas 

 is heavier than air by pouring carbonic acid into a jar which 

 contains only air, then testing this jar's contents; or pour some 

 into a jar at the bottom of which is a lighted candle. 



Many other experiments can be made with the carbonic acid, 

 making the pupils familiar with its properties. 



Diffusion of Gases. 



That gases diffuse themselves out into the air from the vessels 

 which contain them, may be shown by leaving a jar of carbonic 

 acid uncovered for a short time. Altho heavier than air, it leaves 

 the jar. An inverted jar of oxygen will show the same. Altho 

 lighter than air it will not stay in the jar. The same is true with 

 illuminating gas, vapor of gasoline, of ether, etc. These experi- 



