518 AGRICULTURAL ENGINEERING 



such a way that two jets of flame are directed toward each 

 other, forming a fan-shaped flame. 



Mantles are not used with acetylene burners, owing to 

 the fact that it is almost impossible to light the gas without a 

 slight explosion or jar which would destroy the mantle. If 

 mantles could be used they would raise the efficiency of the 

 lamps many fold. 



Cost of Light. If it is assumed that one pound of carbi de, 

 costing $4 per hundredweight, will furnish five cubic feet of 

 gas, and that a burner using one-half cubic foot per hour will 

 furnish a 25-candle-power light, it is easy to calculate the cost 

 of acetylene light per candle-power-hour for comparison with 

 other lighting systems. Thus if % cubic foot of gas costs 4/10 

 cent, which is the cost of 25 candle-power-hours of light, one 

 candle-power-hour will cost 1/25 of 4/10 cent or .016 cent. 



In a test of a portable lamp, made at the Pennsylvania 

 agricultural experiment station, from 127 to 140 candle- 

 power-hours were obtained from a pound of carbide, costing 

 5 9/10 cents per pound. This would make the cost of light 

 per candle-power-hour .043 cent. 



Essentials of a Good Acetylene Generator. All acetylene 

 light plants must have a generator whose function is to feed 

 the carbide to the water, or the water to the carbide, which 

 is less usual, as the gas is used. The essentials of a good 

 acetylene generator may be summarized as follows : 



1. There should be no possibility of the existence of an 

 explosive mixture in the generator at any time. " The National 

 Board of Fire Underwriters has prepared a list of generators 

 which have passed inspection ; and each buyer should see that 

 the makeof machine purchased has been inspected and listed. 



2. The generator must insure cool generation. 



3. The construction must be tight and heavy enough to 

 resist rapid deterioration. 



