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.

The freezing point of zinc as a primary point of the International Temperature Scale

1958 ◽  
Vol 247 (1249) ◽  
pp. 214-224 ◽  
Keyword(s):  
Temperature Scale ◽  
Freezing Point ◽  
Platinum Resistance ◽  
International Temperature Scale ◽  
International Temperature ◽  
Platinum Resistance Thermometers ◽  
Resistance Thermometers ◽  
Accuracy Of Measurement ◽  
Definition Of ◽  
Freezing Point Of Zinc

The technique is described of achieving the highest accuracy of measurement with platinum-resistance thermometers at the freezing point of zinc and the boiling point of sulphur. The two points are compared in a series of measurements and it is found that the zinc point is some three or four times more reproducible than the sulphur point. It is concluded that the substitution of the zinc point for the sulphur point as a primary fixed point of the International Temperature Scale would lead to a greater precision in the definition of the scale. The value of the freezing point of zinc is found to be 419∙5055 ± 0∙002°C.

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.

scholarly journals The freezing point of platinum

1934 ◽  
Vol 146 (859) ◽  
pp. 792-817 ◽  
Keyword(s):  
Fixed Points ◽  
Temperature Scale ◽  
Freezing Point ◽  
High Standard ◽  
National Physical Laboratory ◽  
Basic Point ◽  
International Temperature Scale ◽  
International Temperature ◽  
Physical Laboratory ◽  
Pure Substances

The International Temperature Scale, which has been in force since 1927, is based on certain values assigned to the boiling and freezing points of pure substances and on specified means of interpolation between, or extrapolation beyond, these points. The highest basic point of the scale is the freezing point of gold, defined as 1063·0° C, while for extrapolation from this temperature use is made of the Wien law of radiation, with a certain value of the constant C 2 . Though any temperature above 1063° C is thus completely defined without reference to further fixed points, determinations of such points are of considerable value. In particular, they serve to indicate the degree of reproducibility of the scale by the various users of it, and, when well authenticated, to provide secondary standards for its realization. Of such fixed points the most important has been the freezing point of palladium (1555° C), but the latest developments in furnace technique and refractory materials should now enable the freezing point of platinum to be used with equal, if not greater, advantage. The qualities of platinum which render it especially valuable in this connection are as follows: its freedom from oxidation; its high standard of purity, for which a convenient electrical test is available; its high freezing point (about 1775° C) which approaches the important zone of temperature covered by the electric fighting industry These qualities also make the platinum point especially suitable as the basis for a standard of fight, as has been proposed by a number of experimenters. It is with the two objects indicated above that the National Physical Laboratory has undertaken an investigation concerning the freezing point of platinum the precise scope of which may be defined as follows:— (1) To determine the value of the freezing point in terms of the International Temperature Scale.

THE CALIBRATION OF PLATINUM RESISTANCE THERMOMETERS IN THE TEMPERATURE RANGE 11° TO 90°K

1951 ◽  
Vol 29 (2) ◽  
pp. 142-150 ◽  
Author(s):  
J. M. Los ◽  
J. A. Morrison
Keyword(s):  
Low Temperature ◽  
Temperature Scale ◽  
Platinum Resistance ◽  
National Bureau ◽  
International Temperature Scale ◽  
International Temperature ◽  
Platinum Resistance Thermometers ◽  
Resistance Thermometers ◽  
Corrective Term ◽  
Low Temperature Calorimetry

A set of six platinum resistance thermometers of a form suitable for low temperature calorimetry has been made and calibrated in the region 11° to 90°K. by intercomparison with a similar thermometer which had been calibrated at the National Bureau of Standards. Above 90°K. calibration has been made on the International Temperature Scale.Using the intercomparison data, it has been possible to derive a method whereby for these thermometers the scale for the region 20° to 90°K. may be found to within 0.002°C. by means of fixed points. The method applies a 'Z function' of the type used at the National Bureau of Standards (13), plus a corrective term which depends upon the resistance of the thermometer at the boiling point of hydrogen and upon the normal constants which are determined for the International Temperature Scale above 90°K.

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