Abstract: A method and an apparatus for heat treatment of link chains wherein the link chain is continuously introduced into a high frequency induction furnace for quenching to heat it in a manner such that the austenitizing temperature at curved portions of a link element of the link chain is higher than that at parallel portions of the like element and such that the temperatures change smoothly and continuously between the curved and parallel portions thereby to avoid sudden temperature transitions and thereafter the chain link is rapidly cooled in succession for quenching, and the quenched link chain is also continuously introduced into a high frequency induction furnace for tempering to heat it in a manner that the temperature at the parallel portions is higher than that of the curved portions of the link element and thereafter the chain link is cooled in succession for tempering.

Abstract: An improved method of making finely divided, dry metal halides and sulfides, such as chromium chloride and chromium sulfide which are suitable for use as lubricants and wear-proof and corrosion-proof agents for metals.