George T. Armstrong

Use of a Direct Current Amplifier and Recorder to Balance a Mueller Resistance Bridge

By taking corrective action for electrical noise resulting from alternating current pickup and induced electrostatic charges, it has been possible to use a commercially available high gain dc amplifier and a recorder to balance a G‐3 Mueller resistance bridge. Noise levels below 0.01 μv peak to peak were observed with a response time of approximately five seconds. Using a 25‐ohm platinum resistance thermometer and 1‐ma thermometer current, a precision of 0.0001°C was obtained in temperature measurement. The permanent and continuous record provided offers advantages over the ordinary optical galvanometer for the observation of time‐dependent phenomena and the study of sources of error.

Heats of Formation of Inorganic Fluorine Compounds – A Survey

ABSTRACT This paper examines the current state of measurements leading to heats of formation of the inorganic fluorine compounds, and carbon compounds of one carbon atom per molecule. It is based upon a survey of the literature from 1949 to mid-1961. A bibliography of 625 references is given. Reported values of ΔHf2980, cited from the literature, are listed for individual compounds in eight tables. Related thermodynamic measurements are also listed. No attempt is made to indicate the best values to be assigned when conflicting data exist. As a group the binary fluorine compounds have been the most thoroughly studied. The availability of the thermodynamic information decreases rapidly as the complexity of the compounds increases. Recent developments in certain phases of the calorimetry of fluorine compounds are discussed.