Another recent achievement was the successful development of a method for the complete combustion in a bomb calorimeter of a metal in fluorine when the product is relatively non-volatile. This work gave a heat of formation of aluminum fluoride which closely substantiates a value which had been determined by a less direct method, and raises this property to 15 percent above that accepted a few years ago. Similar measurements are being initiated to resolve a large discrepancy in the heat of formation of another important combustion product, beryllium fluoride.

The development and testing of new apparatus to measure other properties is nearing completion. In one of these, an exploding wire device to study systems thermodynamically up to 6000 ** f and 100 atmospheres pressure, a major goal was achieved. The accuracy of measuring the total electrical energy entering an exploding wire during a few microseconds was verified when two independent types of comparison with the heat energy produced had an uncertainty of less than 2 percent. This agreement is considered very good for such short time intervals. The method of calibration employs a fixed resistance element as a calorimeter. The element is inserted in the discharge circuit in place of the exploding wire, and the calorimetric heating of the element is measured with high accuracy. This is used as a reference for comparing the ohmic heating and the electrical energy obtained from the measured current through the element and the measured voltage across the element.