ACETYLENE 153 



The cheapness of calcium carbide has made it possible for the 

 isolated farmhouse to discard oil lamps and to have a private gas 

 system. When the hard, gray crystals of calcium carbide are 

 put in water, they give off acetylene, a colorless gas which burns 

 with a brilliant white flame. If bits of calcium carbide are 

 dropped into a test tube containing water, bubbles of gas will be 

 seen to form and escape into the air, and the escaping gas may 

 be ignited by a burning match held near the mouth of the 

 test tube. When chemical action between the water and car- 

 bide has ceased, and gas bubbles have stopped forming, slaked 

 lime is all that is left of the dark gray crystals which were 

 put into the water. 



When calcium carbide is used as a source of illumination, 

 the crystals are mechanically dropped into a tank containing 

 water, and the gas generated is automatically collected in a 

 small sliding tank, whence it passes through pipes to the va- 

 rious rooms. The slaked lime, formed while the gas was gen- 

 erated, collects at the bottom of the tanks and is removed 

 from time to time. 



The cost of an acetylene generator is about $50 for a small 

 house, and the cost of maintenance is not more than that of 

 lamps. The generator does not require filling oftener than 

 once a week, and the labor is less than that required for oil 

 lamps. In a house in which there were twenty burners, the 

 tanks were filled with water and carbide but once a fortnight. 

 Acetylene is seldom used in large cities, but it is very widely 

 used in small communities and is particularly convenient in 

 more or less remote summer residences. 



