408 Bulletin 92 



placed on either the dry point or the end point, on account of the rapid 

 cracking which occurs at high distillation temperatures. 



The distillation test is undoubtedly the best index of the suit- 

 ability of an oil as an engine fuel. It is difficult to make, requiring 

 considerable technique, and only the largest buyers of oil can be ex- 

 pected to provide themselves with apparatus. The Experiment Sta- 

 tion can make a limited number of tests for users within the State, 

 when conditions justify the expenditure of time. In the Station 

 laboratory a standard 100 c.c. Engler flask and electric heater are 

 used. The thermometer belonging with the apparatus as received has 

 an upper limit of 270° C. After some kerosenes had been run, another 

 thermometer with a limit of 350° C. was secured. It is found neces- 

 sary to provide the flask with asbestos insulation for oils heavier than 

 gasoline. 



The boiling range usually distinguishes between straight refinery 

 gasoline and blends with casing-head gas or "cracked" gasoline. 



SOLIDIFYING POINT 



This is not of importance with ordinary light oils. Benzene, 

 from coke ovens, however, despite its high volatility, freezes at a rela- 

 tively high temperature, about 40° F. 



With boiler fuel oil the solidifying point is important in the win- 

 ter season, as steam coils are required to give the oil sufficient fluidity 

 to flow in pipes. 



SULPHUR CONTENT 



Sulphur and sulphur compounds in oils are objectionable. Va- 

 rious tests for sulphur are in use in laboratories. One of the tests for 

 sulphur in aviation gasoline is the evaporation to dryness of 100 c.c. 

 of gasoline in a copper dish. The bottom of the dish must not be 

 colored gray or black. 



The presence of sulphur leads to corrosion and pitting, particu- 

 larly of exhaust valves. Not over .20 percent should be allowed in 

 gas oil, or .7S percent in diesel engine oil. 



WATER AND SAND CONTENT 



Sand from the oil wells and water are seldom found in light oils, 

 but frequently in heavy oils. Obviously they are objectionable. They 

 are detected easily in light oils, both water and sediment sinking to 

 the bottom of a container. To make the separation in the case of boiler 

 fuel oils, a centrifuge has been much used. If the oil emulsion is quite 



