FUEL FOR GAS TRACTORS 113 



distillate of coal used extensively in Europe, has not yet been 

 produced in America on a large scale. Up to the present 

 time engines capable of burning heavy crude petroleums suc- 

 cessfully have also been too heavy to mount in tractors. Our 

 discussion then will be limited to alcohol and the petroleum 

 distillates, since these are at present the most promising from 

 all standpoints. 



Alcohol is the fuel of the distant future. While tests have 

 shown that this fuel has many advantages over gasoline, such 

 as safety, freedom from carbonization, less offensive exhaust, 

 ease in mixing, and greater power from the same size of engine, 

 the cost at the present time puts it out of the question for gen- 

 eral use. Alcohol costs from three to five times as much as 

 gasoline. Ordinarily it contains only from 10,200 to 12,900 

 B.t.u. per pound, according to its purity, as compared with 

 about 20,000 for gasoline or kerosene. According to prolonged 

 scientific tests of an engine designed for gasoline, reported in 

 Farmers' Bulletin 277, it required 1.8 times as much alcohol 

 as gasoline for the same amount of power, with the engine at 

 its best adjustment, while it was found possible by poor adjust- 

 ment to double the consumption of alcohol. Engines designed 

 for using alcohol, however, have shown a much higher thermal 

 efficiency running on alcohol than the best gasoline engines 

 running on gasoline. Since the burning of alcohol produces 

 no smoke to reveal an improper mixture, the ordinary operator 

 is very apt to use fuel wastefully. However, much attention is 

 being given to the production of alcohol from cheaper materials 

 by cheaper processes, and it is logical to expect that denatured 

 alcohol will eventually be sold as cheaply as gasoline. This 

 is especially true, since the price of gasoline is steadily advancing 

 and much of the present high price of alcohol is due to the 

 federal regulations imposed upon its manufacture. We may 

 also expect even a greater degree of improvement in efficiency 

 in alochol engines than in gasoline engines, which are already 

 in a high state of perfection. 



