MATERIALS PRODUCING HEAT AND LIGHT 235 



It can be more easily produced by dropping water upon 

 calcium carbide (CaC2). The carbide may be produced 

 by heating to a high temperature coke (C) and quicklime 

 (CaO). This reaction is represented as follows: 



3C + CaO = CaC 2 + CO. 



Carbon Quicklime Calcium Carbon 



carbide monoxide 



Water reacting with calcium carbide reacts as follows: 

 CaC 2 + 2H 2 O = Ca(OH) 2 + C 2 H 2 . 



Calcium Water Calcium Acetylene 



carbide hydroxide 



Acetylene burns with an extremely hot flame which in an 

 ordinary burner of a fish tail pattern is smoky. A special 

 burner devised so that two fine streams of acetylene mixed 

 with air impinge one on the other will produce a very small, 

 brilliant flame which, when analyzed, is found to resemble 

 in quality sunlight much more nearly than any other illumi- 

 nant. The equation represented by the chemical action in 

 the flame is, 



C 2 H 2 + 5O = 2C0 2 + H 2 O. 



Acetylene Oxygen Carbon Steam 



dioxide 



The range of the mixture of acetylene and air which will 

 explode is much greater than that of other illuminating gases 

 and the violence of the explosion is far greater than in the 

 case of other illuminants, therefore mixtures of acetyl- 

 ene and air are very dangerous. Nevertheless acetylene 

 illumination is veiy efficient. Prest-0-Lite, generally used 

 in automobile lights, is acetylene dissolved in acetone 

 (CH 3 ) 2 CO. 



Acetylene decomposes, when heated, with the liberation 

 of a large amount of heat. When this heat of decomposition 

 is added to that produced when acetylene is burned in a 



