. . . "Further, water-soluble hygroscopic materials, for example, urea compounds, such as urea, thiourea, ethyleneurea, and 1,3-dimethylimidazolidinones, lactams, such as ??-caprolactam, solid glycerins, such as trimethylolpropane and trimethylolethane, and saccharides, such as maltitol, sorbitol, gluconic lactone, and maltose." . .