A RECORDING VACUUM THERMOBALANCE

A recording quartz spring balance is described, with which weight changes up to 1000 mg. can be followed linearly on a millivolt recorder for samples weighing up to 10 g. During the recording operation the sample may be under vacuum or pressure and may be heated or cooled. The maximum practical sensitivity is about 20 millivolts per milligram and the over-all error in reading the record is about 1 millivolt. The temperature coefficient of fused quartz springs is reported to be − (1.25 ± 0.02) × 10 −4 per degree centigrade in the range 20° to 35 °C.The device could be readily adapted for heavier loads and greater weight changes by using less sensitive springs and could be used for measuring dimensional changes of solids with a maximum sensitivity of at least 2000 mv. per millimeter.