From Introduction: "Vocalization in retorts has been, until recently, the only commercial process of producing spelter, hence the zinc mine operators have had to meet the terms of the zinc mine operators have had to meet the terms of the zinc smelters in regard to the following requirements: (1) Minimum percentage of zinc the ore must contain; (2) the chemical combination of the zinc in the ore; (3) the proportion present of those elements that interfere with the successful recovery of the zinc when the ore is retorted. As stated previously, and as will be shown later, a large part of the valuable mineral content of the ore is lost in effecting this concentration. As a result of the other requirements that have to be met in zinc smelting, much zinc is lost in the mining and milling of zinc ore."

Report issued by the U.S. Bureau of Mines discussing the mine stations and safety cars used to reach miners in distress. As stated in the report, "the purpose, equipment, personnel, and construction of its safety cars" is presented. This report includes an illustration, and a map.

Technical report issued by the Bureau of Mines over the different uses of gypsum. The sources and uses of gypsum are presented and discussed. This report includes tables, photographs, and illustrations.