Abstract: The invention relates to copper-based catalysts, processes for their production and their use and to a process for the production of alkyl halosilanes in the presence of said catalysts.

Abstract: The copper powder contains at least one substance, which is not soluble in copper, e.g. Al.sub.2 O.sub.3, TiO.sub.2, SiO.sub.2 or B.sub.2 O.sub.3. For the production of this copper powder, a surplus of copper metal granulate is mixed with an ammonium salt and/or ammonium hydroxide, together with a saline solution in an aqueous solution, while a gas containing oxygen is added, and at a pH-value of at least 4. A copper-containing precipitate is produced, which is separated and treated at a temperature in the range from 150.degree. to 500.degree. C. in a reducing atmosphere. During this process, Cu(OH).sub.2 and Cu-oxide are transformed into metallic copper powder, which contains the dispersoid. The dispersoid content of the copper powder is preferably in the range from 0.1 to 5% by weight.

Abstract: The effectiveness of organic additives acting as inhibitors during the electrolytic deposition of metals from aqueous electrolytes, which contain organic additives for improving the deposition of metal, is electrically measured. In order to permit an improved and more reliable check of the effectiveness of the inhibitor and to permit a controlled supply of makeup inhibitors at the required rate, a partial stream of the electrolyte is supplied to flow at a constant velocity in a measuring cell provided with at least three wire electrodes having a fresh conductor surface, a measuring current of 5 mA to 1.0 A is supplied to the electrodes and is maintained, and the slope of the plotted cathode potential-time curve in the range from 0.1 to 50 minutes is taken as a measure of the effective conecentration of the inhibitor.