Impure Manganese Di-oxide

A FEW weeks ago I had occasion to order a quantity of manganese di-oxide for general lecture and laboratory experiments, and we duly received the same from a well-known firm the name of which it would be invidious to mention. Although in colour the manganese di-oxide was normal, we soon found that its chemical properties were very erratic. When mixed with potassium chlorate and heated gently, the mass inflamed inside the flask, and a reaction proceeded with explosive violence, resulting in the formation of clouds of smoky gas relatively poor in oxygen. When warmed with concentrated hydrochloric acid the action was unusually vigorous, and an inferior grade of chlorine was evolved possessed of a curious odour resembling that of euchlorine. The black colour of the powder rapidly disappeared, yielding a yellow solution, and a white, insoluble residue, which, from its voluminous appearance, suggested silica.