Known as the Early Journal Content, this set of works include research articles, news, letters, and other writings published in more than 200 of the oldest leading academic journals. The works date from the mid--seventeenth to the early twentieth centuries. We encourage people to read and share the Early Journal Content openly and to tell others that this resource exists. People may post this content online or redistribute in any way for non--commercial purposes. Read more about Early Journal

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... ntent at http://about.jstor.org/participate--jstor/individuals/early-journal--content. JSTOR is a digital library of academic journals, books, and primary source objects. JSTOR helps people discover, use, and build upon a wide range of content through a powerful research and teaching platform, and preserves this content for future generations. JSTOR is part of ITHAKA, a not--for--profit organization that also includes Ithaka S+R and Portico. For more information about JSTOR, please contact support@jstor.org. Book Notices. Book Notices. location, high quality, considerable quantity, and structure permitting easy extraction are the four conditions assigned for the present predominance of Lake Superior ores. The great preponderance of hematite among iron ores in this country is shown in the fact that for 1903 this type afforded 86.6 per cent. of the total production. The two leading producing regions at present are the Lake Superior district and the area about Birmingham, Alabama. The opinion of Van Hise is quoted, that the Lake Superior ores may be exhausted in the first half of the present century. The same authority looks forward to the marketing, in the near future, of ores running below 40 per cent. in iron. No other producing district in the world rivals the Superior region, which now affords at least threefourths of the iron ore used in the United States. The current forming of limonite, or bog ore, is strikingly evidenced in the deposition, in Swedish ponds, of depths of I8 inches of this ore in periods varying from fifteen to thirty years. It may surprise most readers to learn that the native copper of Michigan, as now mined, is contained in ores rarely running above I per cent. of native copper. Ninety per cent. of the copper of the United States comes from the States of Montana, Michigan, and Arizona, in the order named. Butte, in Montana, is the greatest producer in the world, the Anaconda mines alone yielding one-seventh of the world's supply. Butte began in I887 to produce in excess of Lake Superior. Fifty pages are devoted to gold and silver, including the silver-lead ores. Under aluminum, the bauxite localities are described, three in number: Georgia-Alabama, Arkansas, and New Mexico. The first was discovered in I887, and the deposits have been worked since that time. The book should be useful to a variety of readers, not only to students of economic geology, but to teachers of general geology and geography, and to all who are interested in the earth materials commonly used by man. A. P. B.