Those relating to carbonic acid and ethylene take in the critical point.

Others, on hydrogen and nitrogen, for instance, are very extended.

Others, again, such as the study of the compressibility of water, have a special interest, on account of the peculiar properties of this substance.

M.Amagat, by a very concise discussion of the experiments, has also been able to definitely establish the laws of compressibility and dilatation of fluids under constant pressure, and to determine the value of the various coefficients as well as their variations.

It ought to be possible to condense all these results into a single formula representing the volume, the temperature, and the pressure.