370 The American Geologist. June, 1891 
manufactured with it and piped to leading industrial centers at 
trivial expense. Already large quantities are being utilized as a 
substitute for charcoal — which it nearest resembles in physical 
properties — in the refinement of sugar. 
REVIEW OF RECENT GEOLOGICAL 
LITERATURE. 
Tlie iron ores of Minnesota. Their discovery, development, qualities 
and origin, and comparison with those of other iron districts; u-ith a 
geological map, 26 figures and 44 plates; 430 pp. 8vo. Br N. H. and 
H. V. Wixchell, Minneapolis, 1891. (The Geol. and Nat. Hist. Sur. 
of Minn. Bulletin No. 6.) 
This is a work which was instigated by the law of 1887, requiring 
the state geologist to make special examinations for the discovery of 
any economic product, as the preface informs us, and certainly the 
authors have no need to apologize for not having sunk the appropria- 
tion in holes in the ground designed to lay bare parts of strata that 
have not been seen before. 
The information contained in this volume is of far greater value than 
the discovery of a new bed of iron ore would have been, because it gives 
the most valuable information not only to the statistician, statesman, 
furnaceman, and miner, but especially to the class to which all of the 
above come for the information which they apply to economical work — 
the class of scientific geologists. 
This work is comprehensively arranged into eight parts and four 
Appendices of which Part I contains all of the valuable new research 
and the rest is devoted to history, statistics, speculations, and lists. 
Nevertheless, so naturally do these latter follow the more original re- 
search of the first part, and so exhaustive is their treatment of the 
various subjects that they may also be said to directly contribute to our 
knowledge. 
Especially is this true of Part IV which is concerned with the origin 
of iron ores ; Part V, the bibliography of this subject with full cita- 
tions from all who have entered this field of theory ; and Appendix A 
which is a disquisition favoring the theory of the precipitation of the 
Keewatin ores and their distribution as a sediment, in opposition to a 
metasomatic genesis. 
The 41 plates, including colored lithographic representations of 
thin sections of rocks, photographs of scenery, machinery, etc., maps 
and tables are admirably executed and worthy of the book which 
marks an epoch in this kind of work. 
A hurried glance at Part I, which has the strongest bearing on the 
future iron industry, shows that it is divided into seven sub-headings 
following a sketch which shows the " recentness " of the development 
of the Minnesota ores. 
