GASEOUS FUELS 103 



quently the carbon soon cools to a temperature at which the 

 reaction stops. The carbon is then heated again by blowing 

 air through the furnace, called the GENERATOR (Fig. 81), in 

 which it is contained. When the carbon again becomes hot 

 enough, the air is shut off and steam is again admitted. Since 

 the carbon monoxide and the hydrogen burn with a blue flame, 

 it becomes necessary to introduce some substance that will 

 render the flame of water-gas luminous. This is done by 

 introducing into the gas vaporized, or gasified, hydrocarbons 

 derived from crude petroleum. The petroleum is sprayed 

 into a CARBURETER which is heated to a very high tempera- 

 ture. Here the petroleum hydrocarbons are broken down into 

 simple hydrocarbons which remain as gases. These are mixed 

 with the water-gas and the mixture is passed through the 

 SUPERHEATER. Such a mixture is known as CARBURETTED 



WATER-GAS. 



117. Gasoline Gas. Gasoline gas is simply air and gasoline 

 vapor mixed in such proportions as to be non-explosive. Air 

 containing less than 1.5 per cent, and more than 6.4 per cent, of 

 gasoline vapor, by volume, when 88B. gasoline is used, is 

 non-explosive, while a mixture containing between 1.5 per cent, 

 and 6.4 per cent, of gasoline is explosive. There are two general 

 processes used for vaporizing the gasoline. One, known as 

 the COLD PROCESS, is described in Art. 45. For this a light oil 

 (88B.) must be used. The other process, known as the 

 HOT PROCESS, uses heat to vaporize the gasoline. This makes 

 possible the use of a heavier, and hence a cheaper, grade of 

 gasoline. In each of these systems, it is expected that the air 

 will carry from 12 to 20 per cent, of gasoline vapor. Gasoline 

 gas is almost always used with a mantle when used to produce 

 light. It may be used in ranges for cooking. The production 

 of gasoline gas offers a convenient means of producing gas in 

 small amounts for home or school use in places inaccessible 

 to a city gas supply. 



118. Acetylene. The preparation and the use of this gas have 

 been discussed in Chap. I, Sec. X. The gas is used to a limited 



