128 POWER AND THE PLOW 



A cubic foot of gasoline vapor will form a violently explosive 

 mixture with a large quantity of air, at ordinary temperatures, 

 hence we can readily understand the cause of many explosions 

 where volatile oils are kept in enclosed rooms. Absolute 

 freedom from leakage is therefore an important essential. 

 Steel tanks are to be preferred to wood receptacles, and welded 

 to riveted seams. 



It frequently happens that the evaporation from the sur- 

 face of gasoline is sufficient to reduce the temperature to the 

 point at which moisture from the adjacent air will condense 

 upon the surface. Being heavier, the water will find its way 

 to the bottom of the tank. As the pump to the carbureter 

 is usually connected with the lowest point in the storage tank, 

 water is thus very apt to get into the carbureter and stop the 

 engine. There are many patent filters for removing water, 

 the common chamois skin being employed in a great many. 

 The gasoline passes readily through this fabric, leaving the 

 dirt and water behind. 



Dirt finds its way into the storage tank through careless 

 handling of the fuel, through rusting of some of the parts and 

 through the chipping off of small pieces of solder. These are 

 naturally pumped into the carbureter, where they clog the 

 small needle- valve openings and stop the engine for lack of fuel. 

 Great care should be taken to keep the storage tanks clean and 

 to prevent the introduction of water and dirt in fuel. 



The water required by gas tractors varies with several 

 factors, such as the load, the atmospheric temperature, and 

 the type of cooling system used. In brake tests during tractor 

 competitions, where steam engines used from 28 to 36 Ibs., 

 gas tractors used from practically nothing up to 2.9 Ibs. of 

 water per brake-horsepower hour, averaging about ij pints. 

 The non-evaporating cooler required the least, and the 

 simple evaporating cooler, the most. Some kerosene tractors 

 which do not use water for cooling, use it in connection with 

 the fuel in the cylinder, at from half to full load. In this case 



