The Triple Point of Oxygen In Sealed Transportable Cells.

The triple points of oxygen samples sealed in miniature pressure cells were investigated by means of adiabatic calorimetry. The triple point of a 99.999 percent pure commercial oxygen sample was found to be 0.

The International Practical Temperature Scale of 1968 in the Region 90.188 K to 903.89 K as Maintained at the National Bureau of Standards.

The reproducibility of the International Practical Temperature Scale of 1968 (IPTS-68) in the region 90.188 K to 903.89 K as maintained at the National Bureau of Standards is discussed.

Investigation of Freezing Temperatures of National Bureau of Standards Aluminum Standards.

The design of a high-precision furnace for investigating the freezing points of metals up to 700 °C or higher is described. The freezing points of aluminum samples of nominally 99.999 percent purity from two batches were compared in terms of the ratio (Al)/(TP), the ratio of the resistance of the platinum resistance thermometer at the aluminum freezing point to that at the triple point of water.

The International Practical Temperature Scale of 1968 in the Region 13.81 K to 90.188 K as Maintained at the National Bureau of Standards.

The reproducibility of the International Practical Temperature Scale of 1968 (IPTS-68) in the region of 13.81 K to 90.188 K using standard platinum resistance thermometers is discussed.

Heat Capacity and Thermodynamic Properties of -Lithium Hexafluoroaluminate, LiAlF, from 15 to 380 K.

The heat capacity of -lithium hexafluoroaluminate, LiALF, was determined from 15 to 380 K and the thermodynamic properties calculated from the results. The entropy at 298.15 K was found to be 187.

Heat Capacity and Thermodynamic Properties of -Beryllium Nitride, BeN, from 20 to 315 K.

The heat capacity of -beryllium nitride. BeN, was determined from 20 to 315 K and the thermodynamic properties calculated from 0 to 315 K. The entropy at 298.

Heat Capacity and Thermodynamic Properties of Beryllium 1:3-Aluminate, BeO · 3AlO, from 15 to 390 °K.

The heat capacity of beryllium 1:3-aluminate, BeO 3AlO, was determined from 15 to 380 °K and the thermodynamic properties calculated from 0 to 390 °K. The entropy at 298.15 °K was found to be 175.

Heat Capacity and Enthalpy Measurements on Aluminum Carbide (AlC) From 15 to 1173 °K. Thermodynamic Properties From 0 to 2000 °K.

Measurements of the heat capacity and relative enthalpy were made on aluminum carbide (AlC) from 15 to 1173 °K. The thermodynamic properties were calculated up to 2000 °K from the data by judicious extrapolation above 1173 °K. In conjunction with the heat-of-formation data on AlC obtained by King and Armstrong and by Mah, second- and third-law analyses have been made of the thermodynamics of several high-temperature vapor-equilibrium reactions involving AlC.

Application of Precise Heat-Capacity Data to the Analysis of the Temperature Intervals of the NBS (1955) and the International Practical Temperature Scales in the Region of 90 °K.

A method is presented for analyzing the temperature intervals of the NBS (1955) temperature scale and the International Practical Temperature Scale (IPTS). Values of as a function of resistance are derived from equations of and , obtained from precise heat-capacity data (better than ± 0.02 percent) by the method of least squares.

Heat Capacity and Thermodynamic Properties of Beryllium Aluminate (Chrysoberyl), BeO·AlO, From 16 to 380 °K.

The heat capacity of beryllium aluminate (chrysoberyl), BeO·AlO, was determined from 16 to 380 °K and the thermodynamic properties calculated from 0 to 380 °K.

Heat Capacity of Potassium Borohydride (KBH) From 15 to 375 °K. Thermodynamic Properties From 0 to 700 °K.

The heat capacity of potassium borohydride (KBH) was determined from about 15 to 375 °K by means of an adiabatic calorimeter. A table of thermodynamic functions was calculated up to 700 °K using the data obtained along with those at high temperatures found in the literature. A solid-solid (order-disorder) transition was observed at 77.

Calorimetric Properties of Some Alkali Pentaborate Hydrates From 15 to 370 °K.

Measurements of the heat capacity of ammonium pentaborate tetrahydrate (NHBO·4HO), potassium pentaborate tetrahydrate (KBO·4HO), and sodium pentaborate pentahydrate (NaBO·5HO) were made in the range of about 15 to 370 °K and the data were used to obtain a table of smoothed values of thermodynamic functions from 0 to 370 °K. The measurements on sodium pentaborate pentahydrate were terminated at 345 °K because the temperature drifts that were observed above this temperature were considered to arise from gradual volatilization of the water of hydration.

Thermodynamic Properties of Some Methylphosphonyl Dihalides From 15 to 335 °K.

Measurements of the heat capacity of methylphosphonyl difluoride (CHPOF), methyl phosphonyl dichloride (CHPOCl), and methylphosphonyl chlorofluoride (CHPOClF) were made from about 15 to 335 °K by means of an adiabatic calorimeter. These highly reactive and toxic substances were purified in a completely closed glass apparatus by combining slow crystallization and fractional melting procedures. The purities determined by the freezing-curve method are shown to be generally in agreement with those values obtained by the calorimetric method.