IN revising the text of this series of notes on Lead and Copper Smelting and copper Converting I shall make but few changes in the original, even when in the light of later experience I should have stated the matter differently. A postscript will be written to each chapter, giving in as condensed form as possible the pro gress in the science, since these notes were written in 1896. The readers of metallurgical works have given a fair portion of their support to the preceding editions, and I trust that they may find that such contradictions as occur in the newer portions show a healthy search for truth.