In the course of a series of experiments upon fusion point, as determined by the mercurial thermometer, I had occasion to investigate several of the properties of that instrument. In the hope that the results of that investigation may economise the labour of other experimenters, and aid in its accuracy, I have ventured to submit them to the consideration of the Society. The memoir comprises the following sections:—
I. Calibration and the calibration unit.
II. The exposure correction.
III. The movement of the zero with (α) time, and (β) temperature.
IV. Poggendorff's correction.
V. Comparison of the mercurial with the air thermometer.
VI. Effect of compression.