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Magnesium perchlorate is the magnesium salt of perchloric acid it is a chemical solid.(End user certificate required)
M 1287 (OTTO) Magnesium perchlorate, hydrate, GR 99% Cas 64010-42-0 - used as desiccant to dry gas or air samples, but is no longer advised, for use as a general desiccant, due to hazards inherent in perchlorates.