a mixture of finely divided lead and tetragonal PbO in the proportion of 30% lead and 70% PbO. Although this material is generally satisfactory, it suffers from the disadvantages that it is variable in composition and requires lengthy processing after pasting to oxidize free lead. Plates made from Lead Oxide also require cycling before they achieve full capacity.Lead Oxide manufactured by the ball mill process is almost pure tetragonal while that produced by the Barton Process contain up to 10% of the orthorhombic form, depending on the temperature during the process.