Friedrich Raschig invented the rings on the 1880s, but did not patent them until the 1910s. Due to simple cylindrical shaped tube with an aspect ratio 1:1, the liquid will move in the thousands of channels formed by the rings, coating the inside and outside surfaces, and eventually flowing to the bottom. Gas entering at the bottom will flow through the same paths formed by the rings, and will have time to contact and react with the liquid.
