Infusō′rian.—Infusorial earth, a siliceous deposit formed chiefly of the frustates of Diatoms—used as Tripoli powder for polishing purposes.

As compared with certain kinds of charcoal, however, the absorptive and retentive power of infusorial earth in small changes of temperature unfavorably affect the common dynamite, and cause a separation of the nitrogylcerin from the infusorial earth.

In the manufacture of the explosive known as dynamite, an infusorial earth is used, which is filled with or made to absorb nitroglycerin.

Many substances are incorporated with soap, such as salt, soda ash, tripoli, crushed volcanic deposits, ground feldspar, infusorial earth of various kinds, silex, etc.

Among the organic substances which are usually present in soap are oat meal, bran, sawdust, etc., while among the common inorganic or mineral compounds are pumice, silex, clay, talc, zinc oxide, infusorial earth, sand or other material used as fillers.