While metal has superior anti-trictional properties. Coefficient of friction for a white metal bearing, when lubricated is approximately 0.002. If fluid film lubrication conditions could be constantly maintained and the bearing surfaces kept a reasonable distance apart, metals having specially high anti-frictional properties would not be so necessary and brass would be used more extensively. "Boundary" lubrication conditions, however, occur as certain plinods, and unless white metal is used, the rubbing surfaces will wear at a greater rate. Moreover, the employment of white metal for the bearings of enclosed engines is essential, because in the event of a bearing becoming over heated very little harm is done, whereas if the surfaces were composed of brass and steel, the steel shaft as well as the brass bearing would be seriously damaged. Chloride of Zinc or ral-ammoniac should be used as a flux. After tinning, all surplus flux must be removed. The melted metal level limit should not be more than 3/4, of the ladle height.