A new method for the measurement of extremely low humidities and its application to the testing of desiccants

Abstract

Measurement of the efficiency of desiccants has in the past been limited in accuracy by the necessity of determining relatively small differences in weight with a lapse of days or weeks between weighings. A method is described, based on the use of the electrolytic hygrometer, whereby this and other difficulties are avoided and an increase in sensitivity of several orders of magnitude is obtained. Results are given for most of the desiccants in common use, and it is shown that some of the more efficient desiccants are capable of drying gases to much lower levels of water content than is suggested by previously published figures. Appendices describe the more general application of the technique to the determination of water in microgram and sub-microgram amounts from other sources, and also some of the special apparatus used.