HYDROGEN PEROXIDE AND ITS ANALOGUES: II. PHASE EQUILIBRIUM IN THE SYSTEM HYDROGEN PEROXIDE – WATER

1951 ◽  
Vol 29 (2) ◽  
pp. 123-132 ◽  
Author(s):  
William T. Foley ◽  
Paul A. Giguère
Keyword(s):  
Hydrogen Peroxide ◽  
Phase Equilibrium ◽  
Solid Solutions ◽  
Freezing Point ◽  
Platinum Resistance Thermometer ◽  
Platinum Resistance ◽  
Radioactive Tracers ◽  
Resistance Thermometer ◽  
Pure Solution

A precision freezing point apparatus with platinum resistance thermometer was used to investigate the system hydrogen peroxide – water over the whole concentration range. The freezing point of the purest sample of hydrogen peroxide obtained by repeated fractional crystallizations of a large quantity of 99.6% pure solution was found to be −0.461°C; that of the dihydrate was −52.10°C. The two eutectics occur at concentrations of 45.2% and 61.2% H2O2 and at temperatures of −52.4° and −56.5°C. respectively. Contrary to what has been reported previously, water and hydrogen peroxide do not form solid solutions together. This was proved conclusively by applying the technique of radioactive tracers to the 'wet residue' method of Schreinemakers.

THE REPRODUCIBILITY OF THE SULPHUR POINT

1960 ◽  
Vol 38 (8) ◽  
pp. 1027-1047 ◽  
Author(s):  
R. J. Berry
Keyword(s):  
Boiling Point ◽  
Temperature Scale ◽  
Freezing Point ◽  
Impurity Content ◽  
Platinum Resistance Thermometer ◽  
Operating Conditions ◽  
Platinum Resistance ◽  
Resistance Thermometer ◽  
International Temperature Scale ◽  
International Temperature

The reproducibility of the normal boiling point of sulphur, a fixed calibration point on the International Temperature Scale, has been investigated using a closed manometer-boiler system. Measurements embracing several sources of sulphur and a number of changes in the operating conditions have shown that the sulphur point can be reproduced with a standard deviation of about 0.001 °C with our apparatus.Tests were made on eight samples of sulphur from three different sources in an attempt to resolve the uncertainty in the time the sulphur takes to reach temperature equilibrium after it has been brought to the boiling point. The results indicate that pure sulphur will reach equilibrium almost immediately but that an impurity content of as little as 0.01% can delay equilibrium up to 10 days. The temperature–time dependence can be ascribed to the effect of impurities on the time required for allotropic equilibrium to be attained. This hypothesis is discussed in detail and it is shown that it gives a consistent interpretation of the results presented here and those of previous investigations. The merits of replacing the sulphur point with the freezing point of zinc on the International Temperature Scale are also examined.The long-term stability of the coefficients of a Meyers platinum resistance thermometer is determined and a method of improving this stability for prolonged use at high temperatures is outlined.

A Low-Noise Thermistor Bridge for Use in Calorimetry

1974 ◽  
Vol 20 (8) ◽  
pp. 1009-1012 ◽  
Author(s):  
Robert L Berger ◽  
Walter S Friauf ◽  
Horace E Cascio
Keyword(s):  
High Speed ◽  
Platinum Resistance Thermometer ◽  
Low Noise ◽  
Platinum Resistance ◽  
Resistance Thermometer ◽  
Thermistor Bridge ◽  
Flow Calorimeter ◽  
Titration Calorimeter ◽  
Lock In

Abstract A precision thermistor bridge and thermistor is described for use in a thermal titration calorimeter or a high-speed stopped- or continuous-flow calorimeter of the Roughton type. These are compared and evaluated with regard to several other types of detectors, including the platinum resistance thermometer, thermocouple, transistor thermometer, and capacitance thermometers. At this time the best detection for our purpose seems to be a specially constructed 20-100 kΩ thermistor used in conjunction with a new ac lock-in amplifier bridge. The sensitivity of the system is equivalent to a peak-to-peak noise of 25 x 10-6 °C, with a 100-ms time constant and 1 µW power dissipation in the thermistor. Long-term drift of the bridge, without an oven, was 1 x 10-6 °C/min.

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