Jack Winnick

PVT Behavior of Water at Negative Pressures

Measurements have been made of the extension of a column of liquid water in a centrifugal field. Schlieren photographs of the meniscus position were made at rotational speeds up to 18 000 rpm at temperatures from 5 to 35°C. The data were analyzed using a form of the Tait equation. All of the data were able to be represented well within experimental error, 7.5× 10−5cc/cc. The constants in the equation, found by regression of these negative pressure data, are very nearly those which describe the positive pressure region.

Heat capacities of liquid n-alkanes at elevated pressures

Heat capacities for liquid n -octane, n -decane, n -dodecane, n -tetradecane, and n -hexadecane are reported for pressures up to 4000 atm and temperatures from — 15.00 to 85.00°C. These results are derived from precise p, V, T measurements over this same range of pressure and temperature. Heat capacities and liquid densities at 1 atm, as reported in the literature, were also required. The accuracies of the p, V, T data and the derived heat capacities were checked by comparing the calculated isentropic compressibilities with those derived from experimental speed of sound measurements. The differences averaged ± 1.7 per cent for our p, V, T results and in no case were worse than 5.5 per cent. The error in the heat capacity at any pressure relative to that at 1 atm is probably no worse than ± 7.5 per cent at the highest temperature and pressure.

Excess volumes of octamethylcyclotetrasiloxane + carbon tetrachloride☆

Abstract Densities were measured at approximately 5 K intervals for pure octamethylcyclotetrasiloxane ( omcts ) between 298.88 and 424.10 K, for pure carbon tetrachloride between 252.51 and 345.42 K, and for three mixtures: mole fraction x = 0.2491 of CCl4 between 296.77 and 374.52 K, x = 0.5012 between 297.14 and 355.03 K, and x = 0.7493 between 297.38 and 347.71 K. Excess volumes for the three mixtures were calculated at 5 K intervals over the range 298.15 to 348.15 K and compared with some theoretical predictions. An empirical factor ζ, a correction to the unlike pair diameter σ12, is introduced and shown to be a reasonable means for improving the agreement.

Critical phenomena in the ultracentrifuge: Some new experimental evidence

In 1954 Hildebrand et al. reported that when a hydrocarbon + fluorocarbon mixture was spun in an ultracentrifuge, its critical solution temperature Tc was raised by an amount appreciably in excess of that attributable to the hydrostatic pressure. Two alternative explanations for this anomaly have been offered: a density inversion leading to turbulence mistaken for phase separation, and a “stretching” of the correlation length by the field gradient. We have made ultracentrifuge studies of three critical mixtures, including a hydrocarbon + fluorocarbon one, and find no anomalous rise in Tc.

Evaluation of the air quality in seven urban areas

Abstract CAMP data on air pollutants for 1966 through 1974 and data from selected cities over the same period were analyzed and used in an air quality index based on the root‐mean‐square of the normalized pollutant values. Trends in urban air quality over this period were evaluated and the primary pollutants in each city identified. Only sulfur dioxide (SO2), oxidants, nitrogen oxides (NO), and carbon monoxide (CO) were included in the index because these were the only gaseous pollutants for which sufficient data were widely available. Particulates were omitted despite abundant data because of a lack of standards for particle size composition and distribution with respect to health severity factors. In general, the air quality as here, identified, of the seven cities tested is not changing. The air quality is cyclic yearly and seasonly with the worst air quality severity (highest index value) occurring during the winter season. NOx and CO are responsible for most of the pollution occurring in the winter s...