Abstract: The present invention relates to a method as well as and electrolyte for the electrolytic deposition of mat or half-glossy copper layers from an acid electrolyte in a pull-through device. The method according to the invention is operated with current densities comprises between 10 and 100 A/dm2 and is suitable for depositing sufficiently thick copper layers in high-speed pull-through devices. The electrolyte according to the invention comprises apart from copper, alkyl sulfonic acid.

Abstract: The slightly water-soluble metal salts having the formula I ##STR1## wherein R.sub.1 and R.sub.2 are the same or different and represent hydrogen or a lower alkyl group of from 1 to 3 carbon atoms, M is the cation of a metal which forms slightly water-soluble sulfides, and n means 1 or 2, and mixtures thereof are prepared by reacting carbon disulfide with ketones having the formula II: ##STR2## optionally with the addition of non-aqueous inert solvents, in the presence of strong alkali, preferably potassium hydroxide, followed by precipitation of the slightly water-soluble metal salts of formula I by the addition of aqueous solutions of metal salts of the metals M. They are used as gloss additives to electrolytic baths.