Title screen

[References: 37 tit.]

The dynamic method has been used to determine hygroscopic points of a series of substances in the range of 41 - 69 % RH, which is characterized by a transition from optimal to non-recommended relative air humidity. The hygroscopic points are presented as a decreasing series; their values are mutually consistent with each other; the standard uncertainty of hygroscopic points is 0.3-0.6% RH. The investigated substances are recommended to expand the number of reference substances given in ASTM E 104-02, saturated solutions of which can be used to set relative air humidity in laboratory practice. It is noted that some substances, including those listed in ASTM E 104-02, should be used with caution when studying hygroscopic processes since they (their solutions) release into the gas phase not solely water vapor but also other substances that can distort the hygroscopic process run with the participation of these substances.