THE following investigation was undertaken for the Electrolytic Zinc Company of Australasia, to whom we are indebted for permission to publish the results. The interest taken by the company's staff has been of great assistance during the progress of the work, and we are particularly indebted to Mr. Gilbert Rigg for his interest and help throughout the investigation. The problem is essentially a practical one, but it has opened up a very important field for research, namely the interaction between carbides of iron and chromium with various lead compounds, particularly the sulphide and sulphate. The alloy which has been found to give the best service under the drastic temperature conditions in the roasting furnaces at Port Pixie is one of the following approximate composition :- % Carbon..1.5-3.0 Chromium..26/27 Silicon..5/1.0 Actually three grades of the alloy were in use at the time this investigation was carried out, the quality being decided by the carbon content. It was considered that the life of the teeth increased as the carbon content decreased. The lower carbon content alloy was, therefore, used for the most drastic conditions. The temperatures in the Barrier type furnaces at Port Pixie may reach 950-1000 C., and the teeth are embedded in a zinc concentrate which at the time when this investigation was carried out (1926-7) contained 6% lead sulphide.