instead of being used as a pigment, with the consequent extreme care as regards color and quality, may be used merely as a source of zinc (and lead in the case of a lead-bearing ore). The term "zinc burning" may be applied to any process in which zinc oxide is reduced to the metallic form and then burned back to oxide. Volatilization of the metal and fume is an essential feature of the commercial application of the process. The gangue and nonvolatile material in the ore may be either slightly sintered or fluxed and completely fused. One of the earliest applications of the process was that of F. L. Bartlett at Canon City, Colo., using a low-blast furnace. The process is now developing along the lines of reverberatory smelting. The most successful of recent large installations is that at Great Falls, Mont., where a large reverberatory furnace is used to recover the last zinc from the residues from the electrolytic plant. In Wetherill grates which are used for the making of pigment, the ore is only slightly sintered. There is no running of melted slag and merely enough formation of it to clinker the residuum. In the igneous concentration of ore, the furnace operation is like that of ordinary smelting, slag is formed and tapped out, matte is also formed if there are copper and iron sulphides in sufficient amount. The main distinction is in the amount of fume made. In order to prevent a large loss of zinc in the slag, large amounts of silica are added, as a silicious slag is less likely to contain zinc. A small amount of coal must also be added to the charge in order to reduce the zinc oxide to metal. The necessity of a highly silicious slag is fortunate in that it favors the application of the process to low-grade ores, high in silica. It is a simple means of concentrating low-grade ore, especially calamine, to save freight and treatment charges on worthless gangue. At Canon City, Colo., this is already being done and the product shipped to distillers or electrolytic refiners. The residue from leaching in electrolytic plants has also been treated by this process. The zinc remaining in this residue is largely in the form of zinc ferrite which is difficultly soluble in dilute acid but its zinc is easily volatilized in the furnace. Another important phase of the growing use of this process is the possibility of the treatment of lead blast furnace slags. In the early stages of lead smelting in this and other countries, before ore-dressing methods had progressed to their present efficiency, the lead blast furnace charges were high in zinc. Such a condition still exists at many plants. The resultant slags contain 12 per cent or more of zinc oxide. In Australia, slags as high as 20 per cent have been made. This process is a possible method of recovering the zinc and lead in these old slags and from similar slags in the future. ARIZONA: ZINC ORE PRODUCERS IN THE UNITED STATES,1 Ajax Mining Co., San Simon, Ariz. Bradshaw Reduction Co., Crown King, Ariz. Duquesne Mining & Reduction Co., Duquesne, Ariz. Middle Golconda Mining Co., Golconda, Ariz. Needles Mining & Smelting Co., Needles, Calif. Union Basin Mining Co., Golconda, Ariz. 1 Furnished by the United States Geological Survey. IDAHO: Colonial M. & M. Co., Wallace, Idaho. Consolidated Interstate Callahan Mining Co., Wallace, Idaho. Deer Ridge Mining Co., Salt Lake City, Utah. Douglas Mining Co. (Ltd.), Wallace, Idaho. Greenhill Cleveland Mining Co., Wallace, Idaho. Highland Improvement Consolidated Mining Co., Kellogg, Idaho. Paragon Consolidated Mining Co., Paragon, Idaho. Rex Consolidated Mining Co., Wallace, Idaho. MONTANA: Amalgated Pioche Mining Co., Pioche, Nev. Empire Zinc Co. (Potosi), Denver, Colo. Polar Star Mining Co., Salt Lake City, Utah. Root Zinc Co., Goodsprings, Nev. Singer Leasing Co., Goodsprings, Nev. The Mobile Co., Jean, Nev. Sultan Mining Co., Goodsprings, Nev. Yellowpine Extension Mining Co., Goodsprings, Nev. CALIFORNIA: Empire Zinc Co., Denver, Colo. Big Chief Leasing Co., Leadville, Colo. Castle View Mining Co., Leadville, Colo. Cord Mining Co., Leadville, Colo. Crysolite S. Mining Co., 19 Boston Block, Denver, Colo. Down Town Mines Co., Leadville, Colo. Eagle Mines Mining Co., Red Cliff, Colo. Greenback mine, Leadville, Colo. Gambetta mine, Leadville, Colo. Frank Hoheisel, Almont, Colo. Iron Silver Mining Co., Leadville, Colo. Leadville Exploration & Mining Co., Leadville, Colo. Little Chief Mining Co., New York, N. Y. Lonesville Mining Co., Leadville, Colo. Mary Murphy G. Mining Co., Denver, Colo. A. Y. & Minnie M. & M. Co. (S. D. Nicholson), Leadville, Colo. Monarch Madonna Mining Co., Salida, Colo. Rico Wellington Mining Co., Denver, Colo. Star Consolidated Mining Co., Leadville, Colo. Sunnyside Mining & Milling Co., Silverton, Colo. U. S. Smelters Refining & Mining Co., Leadville, Colo. Western Mining Co., Leadville, Colo. Yak Mining & Transportation Co. (idle), Leadville, Colo. KANSAS: Blue Mound Mining Co., Baxter Springs, Kans. Chanute Spelter Co., Joplin, Mo. Federal Mining and Smelter Co., Baxter Springs, Kans. Freehold Oil & Gas Co., 912 Columbia Bank, Pittsburg, Kans. Southern Lead & Zinc Co., Miami, Okla. Union Metal Mines Co., Joplin, Mo. WISCONSIN: Blockhouse Mining Co., Platteville, Wis. Connecting Link Mining Co., Cuba City, Wis. Field Mining & Milling Co., 2200 Insurance Building, Chicago, Ill. Oliver Iron Mining Co., Shullsburg, Wis. Mineral Point Zinc Co., Galena, II. Vinegar Hill Zinc Co., Platteville, Wis. Wisconsin Zinc Co., 55 Congress Street, Boston, Mass. NEW MEXICO: L. B. Bentley, Las Cruces, N. Mex. Big Four Exploration Co., Hermanas, N. Mex. Consolidated K. C. Mining & Smelting Co., El Paso, Tex. Deming Zinc Mines (Ltd.), Cooks, N. Mex. Empire Zinc Co. (N. J. Zinc Co.). Germany Mining & Development Co. (idle?), Socorro, N. Mex. Edward Leasing Co., Deming, N. Mex. J. A. Mahoney, Deming, N. Mex. Los Cerillos Mining Co., Los Cerillos, N. Mex. Ozark Smelter & Mining Co., (mine at Magdalena), Cleveland, Ohio. WASHINGTON: Lead & Zinc Co., Metaline, Wash. UTAH: Big Four Exploration Co., Salt Lake City, Utah. Broadwater Mills Co., Park City, Utah. Bullion Beck & Champion Mining Co., Salt Lake City, Utah. Caldo Leasing Co., Frisco, Utah. Cedar Talisman Mining Co., Salt Lake City, Utah. Chief Consolidated Mining Co., Salt Lake City, Utah. Childers Leasing Co., Salt Lake City, Utah. Eureka Leasing Co. (mine at Mona), Salt Lake City, Utah (idle?). Eva Mining Co., Springville, Utah. Godiva Mining Co., Salt Lake City, Utah. Judge Mining & Smelter Co., Salt Lake City, Utah. Lake View Mining Co., Salt Lake City, Utah. Lower Mammoth Mining Co., Salt Lake City, Utah. May Day Mining Co., Salt Lake City, Utah. Midvale Mineral Conc. Co., Salt Lake City, Utah. Moscow Mining & Milling Co., Salt Lake City, Utah. D. U. Lynch, Gisborn, Utah. Ridge & Valley Mining Co. and Gemini Mining Co., Salt Lake City, Utah. Scranton Mining & Smelter Co., Salt Lake City, Utah. United States Mining Co., Salt Lake City, Utah. Utah Apex Mining Co., Bingham, Utah. Western Zinc Co., Salt Lake City, Utah. Yankee Consolidated Mining Co., Salt Lake City, Utah. Yankee Consolidated Mining Co., Eureka, Utah. Uncle Sam (Humbug) mine, Eureka, Utah. SOUTHWESTERN MISSOURI: American Zinc, Lead & Smelter Co., Carterville, Mo. Athletic Mining & Smelter Co., Webb City, Mo. Connor Investment Co., Joplin, Mo. Connecticut Zinc Co., Oronogo, Mo. Coahuila Lead & Zinc Co., Webb City, Mo. Bertha Mining Co., Webb City, Mo. SOUTHWESTERN MISSOURI-Continued. Oronogo Mutual Mining Co., Oronogo, Mo. Zinc Corporation of Missouri, Joplin, Mo. Acme Lead & Zinc Co., Picher, Okla. Admiralty Zinc Co., Tar River, Okla. Anna Beaver Mine, Tar River, Okla. Bethel Mining Co. and Croesus Mining Co., Tar River, Okla. Commerce Mining & Roy. Co., Miami, Okla. Eagle Picher Lead Co., Picher, Okla. Goodeagle Mining Co., box 536, Joplin, Mo. Golden Rod Mining & Smelter Corporation, Joplin, Mo. Kanoah Mining Co., Picher, Okla. Montreal Mining Co., Douthat, Okla. Ramage Mining Co., Frisco Building, Joplin, Mo. St. Louis Smelter & Refining Co., Miami, Okla. Velie Mine Corporation, Joplin, Mo. Vinegar Hill Zinc Co., Baxter Springs, Kans. SOUTHEASTERN MISSOURI: Valle Mining Co., Valles Mines, Mo. NEW JERSEY: |