... luster, melting point at 622 o C, easily soluble in water, with remarkable chelating ability to some metal ions such as ... Ca 2+, Mg 2+, can soften hard water, change suspension into solution, slightly alkaline, without causticity.2.Usage ... : Used as main auxiliary of synthetic wash, soap synergistic agent, water softener, leather pre-tanning agent, dye auxiliary agent, and dispersant ...