LIGHTING 425 



of gasoline commonly found on the market. Some systems 

 have attempted to use kerosene, and have failed, as have the 

 gasoline plants, because of the poor quality of oil used. 



There is a system known as a gasoline pressure-system. 

 In this installation a small brass tube is run through the 

 walls of the building to the point where light is desired. 

 Here it is brought out and put through a lamp, the special 

 characteristic of which is a thin — usually coiled — generator 

 tube, which must be warmed in order to gasify the oil. The 

 gas is then delivered to the mantle. This installation is very 

 satisfactory as to quantity and quality of light, but has this 

 objection; it calls for gasoline pipe lines through the walls 

 and floors of a building, at 25 to 35 pounds pressure. It is, 

 therefore, not in high standing with the insurance companies. 

 It is quite satisfactory for temporary buildings where the 

 pipe lines are not necessarily covered. 



Attempts have been made to use alcohol in these systems, 

 but the cost.- even when denatured alcohol is used, is suffi- 

 ciently high to exclude them from the market. 



Blau-gas. The next improvement in the oil-gas system 

 is that known as Blau-gas. This gas is made after a process 

 very similar to that known as Pintsck. This latter system 

 has been used for railroad-coach lighting for several years. 

 It consists, essentially, in the heating of a heavy mineral 

 oil, known as gas oil, to a point where it becomes a permanent 

 gas. This point is known as the cracking-point. After 

 being cracked, the gas is washed or scrubbed to remove tar 

 and other foreign matter, and is then put through a com- 

 pressing process and reduced to liquid. The pressure at 

 which it is marketed is 100 atmospheres, or about 1,500 

 pounds. It will immediately return to the gaseous state 

 when released. This compressed gas is not explosive except 

 when it is mixed with air in the proper proportion. The 

 bottles containing the gas at the high pressure are not 

 dangerous to handle. They may be given any ordinary 

 rough usage without fear of accident. It is asserted that air 



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