The expansion of mercury and fused silica between 0 and 300 C

The determinations of the thermal expansion of mercury and fused silica have been reviewed. In principle the absolute hydrostatic balancing method is a more satisfactory way of measuring the expansion of mercury than deducing it from the expansion relative to a fused silica bulb, but a discussion of the determinations shows that despite the variability of the expansion of fused silica from specimen to specimen, systematic errors affecting the absolute determinations make them less reliable than the relative measurements of Harlow and Beattie and others. It is recommended that for the most accurate work, the expansion formula given by the latter authors should be used instead of that given by Sears. The present uncertainty of the change of volume with temperature is about one or two parts in a million of the volume at 0° C for temperatures from 0 to 300° C, and may be as much as one part in ten thousand at other temperatures.