IN its present development matte-smelting is applied in the extraction of gold, silver, copper, nickel, cobalt, and lead from their ores. It is probable that more than one-half of the world's supply of copper is obtained in this way, while the proportion of silver thus procured is very large and is yearly increasing. We do not possess precise statistics bearing on the subject, but approximate estimates appear to show that the aggregate value of the metals which are extracted annually throughout the United States by means of matte-smelting methods has now reached the magnificent total of thirty millions of dollars. The interest that is naturally felt in metallurgical processes which are accomplishing such vast results is increased by the fact that they are in a con dition of rapid improvement and expansion, exhibiting at the present moment a vitality and a progressiveness as great, perhaps, as is elsewhere shown in the whole range of metallurgy. 'we may confidently expect not only a higher perfection in their application to the metals of the foregoing list, but also the extension of the principles of the art of matting to the benefication of ores of other metals and metalloids. It is not unreasonable to expect that in the perhaps immediate future we may by such means recover arsenic, antimony, tin, bismuth, and the metals of the platinum group; and that by modifications and combinations of already known processes, sulphur itself may be practically recovered as it issues from the fiues of the matting furnace. Most metallurgists will doubtless coincide in the assertion that matte-smelting is therefore unequaled in the variety and extent of its applications, as well as in its probable future expansion, by any other process, or system of processes, known to their art.