Report issued by the U.S. Bureau of Mines on the air quality in metal-mines after using wet drills. Dust samples are collected and compared to samples collected from similar metal-mines in South Africa and Australia. This report includes tables.

Report issued by the U.S. Bureau of Mines on the possibilities of increasing fuel production from crude oil. Methods of recovering oil that is lost by remaining uncondensed are presented. This report includes tables, graphs, and illustrations.

Report issued by the Bureau of Mines over experiments conducted on coal-dust explosions. The results of the experiments are presented and discussed. This report includes tables, illustrations, and photographs.

From Introduction: "Information concerning the fusibility of coal ash has become of considerable value to the consumer of coals, mainly in connection with the troublesome formation of clinker from the melting of the ash constituents of the burning coal. It is hoped that this information when used together with the large number of coal analyses published by the bureau will assist the consumer of coal in comparing different coals, and in selecting the coal best adapted for his purpose."

On the night of June 8, 1917, the flame of a carbide lamp accident set fire to the uncovered and frayed insulation of an armored power cable near the 2,400-foot level of the North Butte Mining Co.'s Granite Mountain shaft. How this insulation accidentally became exposed is explained on page 15. The following pages present an attempt to draw some practical conclusions and suggestions from this disaster."

From Introduction: "The present bulletin presents analyses and descriptions of samples collected during the fiscal years 1916 to 1919. In order that the material in this bulletin may be used to supplement that presented in Bulletins 22, 85, and 123, the same plan of geographical classification has been followed, the analyses and descriptions of the samples being grouped in alphabetical order according to the State, country, and town near which the mines or prospects sampled are situated."

Technical paper issued by the Bureau of Mines over shaft sinking safety. Safe mechanical equipment and procedures are discussed. This paper includes illustrations.

Technical paper issued by the Bureau of Mines over progress made for thawing gravel in placer mines. Different thawing tests are presented and discussed. This paper includes tables, photographs, and illustrations.

Technical paper issued by the Bureau of Mines over studies of coal tars. As stated in the introduction, "this paper discusses the uses to which some of the various tars are put and shows briefly the usual methods of working up tar into some of its simple or easily prepared derivatives, for which a market can generally be found" (p. 5). This paper includes tables, illustrations, and photographs.

Report issued by the U.S. Bureau of Mines discussing studies conducted on the development of the oil-shale industry from a historical, technical, and economic perspective. Results of the studies are presented. This report includes tables, illustrations, and photographs.