336 Attempt to determine the Adiabatic Relations of Ethyl Oxide. 



" An Attempt to determine the Adiabatic Relations of Ethyl 

 Oxide." By E. P. PERMAN, D.Sc., W. RAMSAY, Ph.D. 

 F.R.S., and J. ROSE-INNES, M.A., B.Sc. Received November 

 6, Read December 10, 1896. 



(Abstract.) 



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 gram. Making use of the same appa- 

 ratus throughout, the results obtained are to be regarded as com- 

 parative, 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 th 

 adiabatic elasticity and tables of the experimental results, and (Y) 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 = bT a. 



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, 



E = jT-A, 



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 g/b, and this fraction, on being calculated from 

 the data 'available, proves to be nearly constant. For working pur- 

 poses it is assumed that g/b may be treated as strictly constant, and 



