Page:Proceedings of the Royal Society of London Vol 60.djvu/363

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The wave-length of sound in gaseous and in liquid ethyl oxide (sulphuric ether) has been determined by the two first-mentioned of the authors, by means of Kundt’s method, between limits of temperature ranging from 100° C. to 200° C., and of pressure ranging from 4000 mm. to 31,000 mm. of mercury, and of volume ranging from 2'6 c.c, per gram to 71 c.c. per gi’am. Making nse of the same apparatus throughout, the results obtained are to be regarded as comparative, and, by careful determination of the pitch of the tone transmitted through the gas, it is probable they are approximately absolute.

The sections of the complete memoir deal with (I) a description of the apparatus employed, (II) the method of ascertaining the weights of ether used in each series of experiments, (III) determinations of the frequency of the vibrating rod, (IV) the calculations of the adiabatic elasticity and tables of the experimental results, and (V) a mathematical discussion of the results. The last section is due to Mr. Rose-Innes.

As the theoretical results are of interest, a brief outline of them may be given here.

It will be remembered that one of the authors, in conjunction with Dr. Sydney Young, showed that for ether, and for some other liquids, a linear relation subsists between pressure and temperature, volume being kept constant, so that p = &T—

It has been found that a similar relation obtains between adiabatic elasticity and temperature, volume, as before, being kept constant; so that, within limits of experimental error, where E stands for adiabatic elasticity,

g and h being functions of the volume only. Between these two equations, we may eliminate T, and so express E as a linear function of. p, volume being kept constant. The coefficient of p in such an equation would be gib, and this fraction, on being calculated from the data available, proves to be nearly constant. For working purposes it is assumed that g/b may be treated as strictly constant, and