New me as urements of the vapor press ures and PVT prop erti es of e than e are reported . PVT de te rminations have bee n mad e from near th e triple point to 320 K at press ures to 33 MPa. Th e de nsity ra nge inves ti gated exte nd s to more than three tim es th e c riti cal densit y. Th e ne w meas urements of th e vapor press ures of et hane exte nd from 160 K to near the c riti cal point.

benzonitrile t l-propanol -196.01 96.40 -85.39 2 RaO, M. V. P.; N a b , P. R. J . chem. Tlwwmodyn. 1974, 6 , 1195. Reo. M. V. P.; Nab, P. R. J . Chem. m. 1976, 8, 73. Rao, M. V. P.; Nab, P. R. J . Chem. 7B"dyn. 1976, 8, 96. Reddy, K. S.; Naldu, P. R. J . Chem. -. 1976, 8, 1208. Reddy, K. S.; Naldu, P. R. J. Chem. Thrnnodyn. 1978, IO, 201. Reo, M. V. P. Ph.D. Theski, Srl Venkateswara Unlversfty, Tlrupatl. Indla, 1974, Chapter 2. Tlmmermens, J. "Physlcochemlcal Constants of Pure Organic Compounds"; Elsevler: New York, WS5.

The speed of sound in saturated pure water has been measured between 273.16 and 534.69 K at 7.5 MHz using the pulse-echo-overlap method. An equation was fitted to our data within the experimental uncertainties of 0.05 %. This equation predicts the values of speed of sound over the whole vapor pressure curve with an assigned zero value at the critical point. Our data were combined with available density data to obtain the isentropic compressibilities.

A metastable solid phase of ethaneThe melting pressures of ethane at 14 temperatures from near the triple point to 95.50 K and pressures to 32.0 MPa are reported. A triple point temperature of 90.348 ±0.OO5 K is obtained from the data which is in agreement with the determination of Clusius and Weigand (1940) but in substantial disagreement with other determinations. Qualitative evidence has been obtained which indicates the existence of a previously unrecognized solid phase transition along a boundary roughly parallel to the melting line at a temperature about 0.5 K below the melting temperature, suggesting that some previous melting point determinations may have been influenced by a misinterpretation of the effects of this transition.

No abstract