Abstract: A process for the production of mineral tanned or/and re-tanned or/and after-treated leather or pelt, wherein before the mineral tanning, directly after the mineral tanning, directly before the mineral re-tanning, after the mineral re-tanning or/and with the after-treatment of a fatliquoring with a polyvalent metal cation, the substrate is treated with(A) a polymeric carboxylic acid containing .alpha.-hydroxyacrylic acid units, optionally in salt form, as constituent units of the polymer,by which a high exhaustion of mineral (re)tanning agent, an excellent distribution of the tanning agent and very pleasant soft handle of the (re)tanned leather resp. an outstanding water resistance of mineral after-treated fat-liquored leather can be achieved.

Abstract: The invention is concerned with a gas hot water heater intended for installation in a wall and including a combustion chamber from which are guided heating gas tubings within a water-carrying housing. The housing is provided with connections for forward and rearward flow of water and an exhaust gas collecting chamber provided with connections for exhaust gas and condensate discharge. In the practice of the invention, a heating gas tubing passing from top to bottom through the water-carrying flat box-type housing is in the form of at least one pocket extending parallel to a broad rear wall of the housing. A water-cooled combustion chamber, disposed in an upper portion of the housing substantially corresponds, in plan view, to a flat rectangular cross-section of the housing. A burner insert opening of the combustion chamber is provided within or approximately within the plane of a front wall having a width corresponding to, and extending parallel with, a rear wall.

Abstract: In a process for the preparation of heterologous arterial transplants comprising freeing young animal arteries of surrounding tissue, ligating collateral branches, subjecting the resulting arteries to proteolysis to remove elastic fibers and muscle tissue to obtain collagen tubes and tanning the latter tubes to effect cross-linking, the improvement comprising effecting the proteoylsis and tanning steps in a continuous flow manner.