THE ignition and detonation phases of the fuel problem were discussed in a previous paper which is cited, C.F.R.-engine data for 20 fuel oils being given, and the results were expressed in terms of the critical compression ratio. Since then, further analysis of the data indicated even better correlation between the critical compression ratio and a function of aniline point and gravity.Since both of these physical constants are so readily determinable by simple and standardized laboratory methods, the authors propose that this function be used as a “Diesel Index” of ignition and combustion characteristics of fuel oils.The present paper shows the correlation of this “Index” with critical compression ratio, not only by use of the data cited in the paper referred to but also for some 30 additional fuels.THE ignition and detonation phases of the fuel problem were discussed in a previous paper which is cited, C.F.R.-engine data for 20 fuel oils being given, and the results were expressed in terms of the critical compression ratio. Since then, further analysis of the data indicated even better correlation between the critical compression ratio and a function of aniline point and gravity.Since both of these physical constants are so readily determinable by simple and standardized laboratory methods, the authors propose that this function be used as a “Diesel Index” of ignition and combustion characteristics of fuel oils.The present paper shows the correlation of this “Index” with critical compression ratio, not only by use of the data cited in the paper referred to but also for some 30 additional fuels.THE ignition and detonation phases of the fuel problem were discussed in a previous paper which is cited, C.F.R.-engine data for 20 fuel oils being given, and the results were expressed in terms of the critical compression ratio. Since then, further analysis of the data indicated even better correlation between the critical compression ratio and a function of aniline point and gravity.Since both of these physical constants are so readily determinable by simple and standardized laboratory methods, the authors propose that this function be used as a “Diesel Index” of ignition and combustion characteristics of fuel oils.The present paper shows the correlation of this “Index” with critical compression ratio, not only by use of the data cited in the paper referred to but also for some 30 additional fuels.THE ignition and detonation phases of the fuel problem were discussed in a previous paper which is cited, C.F.R.-engine data for 20 fuel oils being given, and the results were expressed in terms of the critical compression ratio. Since then, further analysis of the data indicated even better correlation between the critical compression ratio and a function of aniline point and gravity.Since both of these physical constants are so readily determinable by simple and standardized laboratory methods, the authors propose that this function be used as a “Diesel Index” of ignition and combustion characteristics of fuel oils.The present paper shows the correlation of this “Index” with critical compression ratio, not only by use of the data cited in the paper referred to but also for some 30 additional fuels.THE ignition and detonation phases of the fuel problem were discussed in a previous paper which is cited, C.F.R.-engine data for 20 fuel oils being given, and the results were expressed in terms of the critical compression ratio. Since then, further analysis of the data indicated even better correlation between the critical compression ratio and a function of aniline point and gravity.Since both of these physical constants are so readily determinable by simple and standardized laboratory methods, the authors propose that this function be used as a “Diesel Index” of ignition and combustion characteristics of fuel oils.The present paper shows the correlation of this “Index” with critical compression ratio, not only by use of the data cited in the paper referred to but also for some 30 additional fuels.