URL: 

zinc chloride

1. n. [Drilling Fluids]
An acidic salt, ZnCl2, used as one of the standard saturated salt solutions for calibration of the electrohygrometer. Saturated zinc chloride solution at room temperature has 10% relative humidity. Zinc chloride can be used to scavenge sulfides from a mud system in cases where the addition of a chloride salt will not cause detrimental effects on mud performance, such as in a saltwater mud.