Studies on the Hygroscopicity of Water-Soluble, Crystalline Drugs. III

Abstract

The experimental equation (5) which was derived from the relative formula (3) x_1c (x_1a, x_1b), in the previous report, whose x₁ was replaced by H, is widely applied and coincided well with the actual value better than with that of Elder equation (6).
Employing the x_1c (x_1a, x_1b) formula, the validity of the equation (6) was examined. It was found that the mixture which holds the equation (5) is in A and B area in Fig. 1, and that the one which accords with the (6) present only in the B area. For the mixture which is in C area and is afar outside from the boarder line (2), any equation was inapplicable.
As it is informed in the previous report, equation (1) coincided well with the actual value than with (5), and the equation (1) gives more exact value of CRH, if x_1c is known, but the CRH may be estimated roughly from equation (5), if x_1c is unknown.