HE ACCOMPANYING chart was suggested by the Johnson-Duhring relation between the temperature of a saturated vapor and the temperature of steam a t T the same pressure-However, if we integrate Clapeyron's equation on the assumption that the volume of the liquid is negligible compared with the volume of the vapor, that the latter follows the gas law, and that the latent heat is constant for the temperature range, it takes the form This curve is nearly a straight line.

No abstract

HIS survey is part of a general plan to coordinate the vapor pressures of the paraffin series by means of the formula:where P = vapor pressure, atm.T and B = the same in abs. temp.,This equation is peculiarly suited for the purpose in that it contains but one coefficient to be evaluated, and the latter varies only about 17 per cent in the longest range exploredthat of octane. Hence a compact plot of A 7-q. t may be made to a scale sufficiently sensitive to represent accurately the entire vapor pres-ure range of a substance. This xi11 be taken up in a later article. It 15 evident that general coordination of a series require< an accurate and consistent set of boiling point3 for use in Equation 1. Since this surrey proved to be somewhat extensive and contained points of intrinsic interest, it was thought best to publish it as a separate article but preliminary to the vapor pressure investigation.Past attempts a t correlating the boiling pointh of the paraffin series hare met with three obstacles: (a) the erratic placing of the boiling points of methane and ethane, (b) conflicting data for propane and butane, and (c) the low boiling points of Kraft (6) for the higher molecular nreiglits, showing a sharp break between octane and nonane.X.