diagram shows the temperature time pairs which will bring about the aforesaid surface changes without adversely affecting the internal crystalline structure of the talc if conditions are too severe area g above hatched area z the talc is converted into enstatite with loss of its internal properties sheet structure and softness in particular if conditions are too mild area k below the hatched area the energy imparted is too weak to cause the tetrahedra to be overturned and confer significant hydrophilic surface properties with times less than 10 minutes the temperature throughout the sample is not satisfactorily uniform over two hours the time no longer has any effect as the product does not change any more in practice for economic reasons times are limited to less than two hours the starting material was the same as in example 1 and five samples were treated with different quantities of a free radical initiator consisting of benzoyl peroxide the talc in each sample was suspended in carbon tetrachloride containing for every 100 grams of talc each mixture so constituted was placed in a sealed reactor and stirred for 12 hours at 130 u00b0 c the decomposition temperature of the free radical initiator was 71 u00b0 c 10 hour half life temperature this temperature of 130 u00b0 c was selected following several individual tests for decomposition of the initiator and maintenance of the free radical reaction the products obtained were cooled removed from the reactors filtered and washed with carbon tetrachloride the powders were dried in a stove at 100 u00b0 c for 24 hours diffraction spectrum unchanged precisely identical to that of.