Abstract

The spectrographic analysis of lubricating oil directly on the whole oil has been done with four different techniques, and innumerable variations have been described in the literature. One technique employing electrodes prepared by quenching hot graphite rods in the oil sample (1) has been found to have a very limited usefulness (2) and so will not be discussed in this paper. A second technique using porous cups (3) has a more general application but has been shown to give erroneous results on used oils. It is thought that this is due to the filtering action of the cup. This method also will not be discussed. A third technique, employing a rotating disc carbon electrode (3a, 4), has met with wide usage, and a fourth, and more recent, technique employing a rotating platform (5) with preheating is being tried by several laboratories. The purpose of this paper is to describe our work on improving the rotating disc method, and to compare the speed, accuracy, and repeatability with other spectrographic procedures which we have used.

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