Four tables are given listing the determined boiling point at 760-mm. pressure and seven lower pressures and a table listing the infinite points of 23 Cox chart families.THE present investigation was inaugurated a number of years ago when it became necessary to know the barometric boiling point of the forward flow on styrene fractionating columns. In order to do this a table of vapor pressure-temperature relations was developed and this required an accurate knowledge of at least two boiling points at their respective pressures. It became necessary to set up Cox chart families, and for this purpose data on at least three compounds of the family were required.The only families for which these data were available in the required accuracy were the aliphatic hydrocarbons, benzene hydrocarbons, cyclohexanes, and cyclopentanes. The data on these were determined by the Bureau of Standards (3). In order to set

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The vapor pressures of 30 purified samples of organic compounds have been determined by a dynamic boiling point method (3). For 29 compounds, the constants in the Antoine vapor pressure equation were determined from experimental data by a least squares method using an automatic computer.For pentachlorophenol, the constants were determined from a plot of log p, 1 / T (T in °K.). Eight solid state vapor pressures, a heat of fusion of 7000 cal. per mole, and the selected vapor pressures (2) were considered in determining the "best straight line" through three liquid state vapor pressures. The Knudsen effusion technique (I) was used by G. C. Sinke of these laboratories to determine the solid state vapor pressures.The standard deviation, , of the temperature differences is included in Table I.The samples were analyzed by freezing curve techniques (3) except as noted in Table II), and all were better than 99.5 mole % pure, assuming ideal behavior. The freezing point and purity data and the Antoine constants are listed in Table II. Temperatures calculated at selected pressures are in Table III.