acetone and 70 g of a silicone surfactant commercially available under the tradename x 24 3504 produced by shin etsu chemical industry co ltd were added to 1 liter of the magnetite slurry the resulting mixture was agitated for 30 minutes the mixture was then transferred into a separating funnel and then held still to separate it into a supernatant and water layer which were separated consequently the magnetite particles were transferred to a solution comprising dimethylsiloxane and acetone creating an intermediate carrier in which ferromagnetic fine particles having their surfaces coated with the silicone surfactant were dispersed the intermediate carrier was subjected to centrifugal separation for 20 minutes using a centrifugal force of 8000 g to settle and separate large magnetite particles the particle diameter of the ferromagnetic fine particles remaining in the supernatant liquid between 100 a and 150 a the supernatant liquid was then transferred into a rotary evaporator kept at 90 u00b0 c where the dimethylsiloxane and acetone were removed by evaporation ten grams of the powered magnetite fine particles thus obtained was dispersed in a mixture 100 ml of acetone one hundred milliliters of each of ultraviolet curing silicone resin solutions commercially available under the tradename kns 5002a and kns 5002b produced by shin etsu chemical industry co ltd was added to the magnetite solvent mixture and.