... with 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. Application ... of the main auxiliaries for synthetic detergent, synergist for soap; water softener, tanning agent for leather making, auxiliary for dyeing; 2 ...