Abstract: A device is provided for conveying separately at least two gases as far as a mixing zone, said device including several tubes, and means for supplying these tubes with one of the gases, the invention also relating to a reactor having at least one cell equipped with said conveying device, said device further including means for holding the tubes in position with respect to each other, the tubes being held together jointingly by said means and defining empty spaces or intertube gaps, some at least of said tubes having narrowed zones placed substantially at the same level so as to form a network for distributing the other gas to some at least of the intertube gaps.

Abstract: A method of regulating combustion by rapid-response monitoring of the gaseous effluents leaving a combustion chamber, especially the chamber of an internal-combustion engine, includes the steps of emitting ultraviolet radiation to a zone of small volume traversed by at least part of the gaseous effluents leaving the combustion chamber; receiving at least part of the ultraviolet radiation which has passed through this zone; measuring the degree to which the ultraviolet radiation has been absorbed by a chemical compound contained in the gaseous effluents; and governing at least one parameter influencing combustion within the combustion chamber as a function of the degree of absorption.

Abstract: A pollution control catalyst for a catalytic converter in the exhaust system of an internal combustion engine, which catalyst comprises a support impregnated with (i) at least one platinum group precious metal, and with (ii) cerium base metal, or a combination of cerium and at least one other base metal, is facilely prepared by (1) impregnating a catalyst support with precursor compounds of said cerium base metal, or of said cerium base metal and of at least one other base metal, (2) activating said impregnated support, under a neutral or oxidizing atmosphere, at a temperature ranging from 120.degree. to 800.degree. C.

Abstract: Organic compounds of the formula:[(H.sub.3-n X.sub.n)C -- CO.sub.2 M (CO).sub.m (R).sub.p (L).sub.q ].sub.rin which X is a halogen atom, at least one X being fluorine, M is molybdenum or tungsten, R is a hydride ion or a hydrocarbon group, L is a Lewis base and m, n, p, q and r are integers, are manufactured from fluoracetic esters and molybdenum or tungsten carbonyl compounds. They are useful as catalysts for polymerizing or co-polymerizing unsaturated compounds such as butadiene.

Abstract: Organic compounds of the formula:[(H.sub.3.sub.-n X.sub.n)C - CO.sub.2 M (CO).sub.m (R).sub.p (L).sub.q ].sub.rin which X is a halogen atom, at least one X being fluorine, M is molybdenum or tungsten, R is a hydride ion or a hydrocarbon group, L is a Lewis base and m, n, p, q and r are integers, are manufactured from fluoracetic esters and molybdenum or tungsten carbonyl compounds. They are useful as catalysts for polymerizing or co-polymerizing unsaturated compounds such as butadiene.

Abstract: A lubricating oil composition having an improved viscosity index is manufactured by admixing lubricating oil in major proportion with a butadiene polymer in minor proportion, said polybutadiene having a molecular weight of at least 20,000 and a microstructure of from 65 to 85 % ##EQU1## units, from 2 to 35 % of -- CH.sub.2 --CH.sub.2 --CH.sub.2 --CH.sub.2 -- units and from 0 to 25 % of -- CH.sub.2 --CH = CH--CH.sub.2 -- units.

Abstract: Organic compounds of the formula:[(H.sub.3.sub.-n X.sub.n)C -- CO.sub.2 M (CO).sub.m (R).sub.p (L).sub.q ].sub.rIn which X is a halogen atom, at least one X being fluorine, M is molybdenum or tungsten, R is a hydride ion or a hydrocarbon group, L is a Lewis base and m, n, p, q and r are integers, are manufactured from fluoracetic esters and molybdenum or tungsten carbonyl compounds, They are useful as catalysts for polymerizing or co-polymerising unsaturated compounds such as butadiene.