From Introduction: "Figure 1 shows the location of sources that have been either exploited or seriously considered at one time or another, super-imposed upon a map indicating by small letters the order of consumption of K2O in the leading States; the amount used in these States, together with the percentage of the total consumption of potash used as fertilizer in the United States in 1939, is given in table 1. Figure 2 shows the domestic production and total consumption of potassium salts, in terms of tons of K2O, with the value per unit at the plants, for each year since 1913. Considered together, these two figures tell a significant story."

From abstract: Pt 1. The present work seems to confirm the genetic theory previously published, namely that [Illinois Cave in Rock] deposits were formed by ascending solutions. These solutions probably followed minor fissures that connected below with larger fissures, which in turn probably connected with a major fault zone. It is believed that where such minor fissures extended upward only to the shale or other impervious cap rock, or were greatly reduced in size where they penetrated such beds, the solutions spread laterally along the contact and along the limestone beds beneath it and replaced the limestone. Pt 2. This report is a presentation of the results of an electrical-resistivity survey conducted in the fluorspar-bearing areas of Hardin County, Ill., principally during the field seasons of 1934 and 1935.

Report issued by the U.S. Bureau of Mines on the gas injection methods in the oil fields of Illinois. The results and properties of the injections are presented. This report includes tables, graphs, illustrations, and maps.

Report issued by the U.S. Bureau of Mines on the methods and results of water injection in Illinois oil sands. The operations and properties of the oil sands are presented. This report includes tables, graphs, maps, and illustrations.