English: The active material of the positive plates is a form of nickel hydrate. The tube retainers are made of very thin steel ribbon, finely perforated and nickel plated, about 4 in. long and 1/4 in. and 1/8in. in diameter. The ribbon is spirally wound, with lapped seams, and the tubes reinforced at about 1/2 in. intervals with small steel rings. Into these tubes nickel hydrate and pure flake nickel are loaded in very thin, alternate layers (about 350 layers of each to a tube) and are tightly packed or rammed. The purpose of the flake nickel is to make good contact between the nickel hydrate and the tubes, and thereby provide proper conductivity. The tubes, when filled and closed, are then mounted vertically into the grids.