This reaction proceeds very slowly at room temperature. The addition of cobalt chloride as a catalyst produces a green cobalt-tartrate intermediate and copious evolution of oxygen and carbon dioxide.

The standard series contains six metals commonly associated with allergic patch-test reactions: nickel sulfate hexahydrate 2.5%, gold sodium thiosulfate 0.5%, cobalt chloride 1%, gold sodium ...

The white solid turns blue in the presence of water. A similar reversible reaction takes place between anhydrous cobalt(II) chloride (which is blue) and water to produce hydrated cobalt(II ...