3551.     VAN WINSEN, A., AND BROWN, E. A.  Superfine Asbestos.  Canadian Chem. Process Ind., vol. 32, 1948, pp. 129-132.

        Superfine is the term applied to asbestos when opened to a degree where the individual fibers are exceedingly fine and so minute in diam. that most of them are invisible under the optical microscope.  Electron microscopical study reveals the presence of fibers approximately 20 mμ diam.  It is produced by wet milling in a ball or pebble mill and by subsequent spraying through a nozzle with compressed air.  Its heat-resisting nature, fibrous form, and large surface area suggest the use of superfine asbestos as a catalyst or inert carrier upon which very finely divided catalyst could be deposited.