On the velocity of sound in gases at high temperatures, and the ratio of the specific heats

Abstract

The experiments described in this memoir on the velocity of sound in gases, at temperatures varying from atmospheric to that of a bright red heat, were made with the object of tracing the change in the specific heat of gases with rising temperature, and, if possible, of arriving at formulæ which might be applicable to the extremely high temperatures reached in explosions. The sound method was decided on chiefly for the reasons (1) that the velocity of sound in a heated gas gives a value for the ratio of the two specific heats at the temperature of the experiment, and not as in the method of mixtures at a mean temperature between the highest and lowest point of the heated and cooled gas; and (2) because we had had considerable experience in the use of a chronograph for measuring the rapid movements of flame through gases in long tubes. It is necessary to make it clear at starting that no claim is made that these experiments give more exact determinations of the specific heat of gases than those given previously by experiments over low ranges of temperature; the object has been to obtain by comparative measurements the general gradients of the curves rather than to find the exact value at any definite point.