Excerpt from Thermophysical Properties of Helium-4 From 0. 8 to 1500 K With Pressures to 2000 Mpa In these expressions, the temperature is expressed in Kelvins and the density is expressed in kilograms per cubic meter. For temperatures between T A and tm, the calculated state property is a linearly temperature-dependent weighted average of the state properties calculated from the hei and Hell equations. Thus, in the overlap region, the various calculated thermodynamic properties are not exactly consistent with one another; e. G. The Maxwell relations are only approximate, the numerical integral of CP along an isobar is not exactly the tabulated enthalpy difference, etc. In practice, the errors are on the order of 3 percent or less in the compressed liquid for pressures up to about mpa, but rise to 20 percent or more as the melting line is approached. The problem of obtaining thermodynamic consistency in this overlap region is compounded by the general lack of experimental data in this region, especially at higher pressures. About the Publisher Forgotten Books publishes hundreds of thousands of rare and classic books. Find more at www.forgottenbooks.com This book is a reproduction of an important historical work. Forgotten Books uses state-of-the-art technology to digitally reconstruct the work, preserving the original format whilst repairing imperfections present in the aged copy. In rare cases, an imperfection in the original, such as a blemish or missing page, may be replicated in our edition. We do, however, repair the vast majority of imperfections successfully; any imperfections that remain are intentionally left to preserve the state of such historical works.