Application of a log v-d graph

The fact that only the two physical constants, viscosity and density, are necessary to determine the surface tension of mineral oil fractions, enabled Cornelissen, Harva and Waterman21 to construct a diagram with the coordinates log vand da4°. This diagram has been constructed by projecting the surfaces of equal values of the surface tension in the log v-n-d space model on the log v-d coordinate plane. In the diagram lines of equal values of the surface tension (at 20°C) were constructed (Fig. 43). 

This diagram makes it possible to determine ergo from the measured values of the viscosity and the density. In general the results obtained have the same accuracy as those obtained by direct measurements. 

A third example of the correlation of physical constants of mineral oil fractions is the determination of the surface tension from the ultrasonic sound velocity u and the density 22. 

This determination can be carried out by using a graph with the ultrasonic sound velocity u and the density d as coordinates, as shown in Fig. 44. 

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