Abstract: In a method of foreseeing or detecting break-through of a gas in a gas-adsorbing apparatus utilizing a gas-adsorbing material, the improvement in which the break-through is foreseen or detected by detecting a weight of the gas adsorbed by the gas-adsorbing material. When the gas to be detected contains boron trichloride, the break-through can be foreseen or detected by detecting a color change of a detecting agent such as 1,1'-dianthrimide or a combination of caraminic acid, hydrochloric acid and sulfuric acid, the detecting agent being arranged in a lower stream following the gas-adsorbing material and which shows a color change upon contact with boron trichloride.

Abstract: Silicon tetrachloride is effectively and efficiently produced at a relatively low temperature and at a high yield by (1) feeding a mixture of a silicon dioxide containing substance and carbon to the top of a reactor in which a reaction mixture forms a downwardly flowing moving bed, (2) feeding gaseous boron trichloride to an intermediate portion of the reactor, (3) feeding gaseous chlorine to a portion of the reactor located below the boron trichloride feed portion, and (4) feeding an inert gas to a portion of the reactor located below the chlorine feed portion, whereby a silicon tetrachloride formation reaction is carried out in the moving bed and the formed silicon tetrachloride is recovered from a gas mixture discharged from the top of the reactor.

Abstract: The chlorides of elements of Groups III, IV and V of the Periodic Table, such as, boron trichloride, silicon tetrachloride, zirconium tetrachloride and vanadium tetrachloride are prepared by heating activated carbon particles having a supported aqueous solution of compounds of the elements of Groups III, IV and V of the Periodic Table thereon at a temperature of from 300.degree. through 1000.degree. C. and, then, reacting the resultant activated carbon particles with chlorine.

Abstract: A composite catalyst which is capable of clarifying exhaust gas containing nitrogen oxides therein with a high effectiveness over a long period of time while producing no or a very small amount of undesirable by-products such as ammonia, which comprises a catalytic ingredient comprising oxides of nickel and copper in an atomic ratio of nickel to copper of 1:0.05 through 1 and a catalytic base comprising a refractory inorganic material containing at least 50% by weight of zircon therein, said catalytic ingredient being carried on said catalytic base.