Abstract: A light yet highly workable magnetic substance is disclosed which consists mainly of a wholly novel material, fine crystal spherical carbon represented by C.sub.n X.sub.m where n is an integer selected from the group consisting of 60, 70, 76, 84, etc., m represents a positive number not more than n and not zero, and X represents at least one of hydrogen, fluorine, chlorine, bromine and iodine.

Abstract: The invention relates to a butterfly valve assembly having a stationary valve body formed with an axial fluid flow passage opening and a turnable valve member adapted for full opening, partial opening and full closing of the said passage opening. There is provided further a valve seat ring composed of an inner protecting layer of fluoride containing resin and an outer back-up layer of rubber or its equivalent. According to this invention, at least two parallel ring grooves are provided on the radially outwardly directing surface of the said elastomer layer which has a substantially channel-shaped cross-section embracing a substantial part of the valve body when the valve seat ring is attached in position to the valve body.