122 POWER AND THE PLOW 



A long period of use and waste has exhausted many of the 

 valuable wells. Not only that, but oil from the older fields 

 has lost much of its volatile matter in the form of gas, and is 

 heavier than formerly. Crude oil from other and newer sources 

 has seldom duplicated the high percentage of light gravity 

 distillates, hence has yielded even less of the high grade fuels. 

 Heavy-producing foreign fields, also, generally yield oils of 

 much greater density, and crude oil engines have been more 

 in demand abroad than in this country. 



High gravity fuel is constantly changing in quality and 

 advancing in price. Makers of gasoline carbureters are 

 constantly being forced to meet a new situation. In order to 

 obtain fuel enough to supply the growing trade, and at the 

 same time avoid mixing distillates of a wide range in weight, 

 it will be necessary to use oil of comparatively low gravity on 

 the Baume scale. By using gasoline of 56 B. we can obtain 

 a sufficient quantity from Texas and Oklahoma oils without 

 straining the natural constitution of the oil. This in turn 

 presents greater difficulty in carburetion and involves the 

 changing of the design of most of the present carbureters. 

 Once they are adjusted to heavier fuels, they should be able 

 to handle them without difficulty, except on starting. To 

 do so, however, will require automatic means for taking care 

 of the constant variation in conditions presented by the chang- 

 ing loads. By adopting the lower gravity products the situa- 

 tion will become settled for many years. The heavier standard 

 fuels can already be supplied in abundance, and permanent 

 standards of quality can be set up for the benefit of refiner, 

 user, and designer. 



Great changes took place in the oil situation hi the last 

 few decades. Forty years ago kerosene was refined for use in 

 lamps, while gasoline was a by-product. Gasoline of 76 

 to 85 B. was disposed of hi enormous quantities by burning 

 in the open air. The change in quality of crude oil brought 

 a decrease in the percentage of gasoline and an increase in the 



