504 



SCIENCE. 



[N. S. Vol. Xr. No. 274. 



cient of error, if such we regard it, will be cod- 

 staut through his work. 



In the first edition of Kemp's work, there 

 was some evidence of haste in preparation, for 

 which, apparently, the publishers' demand for 

 copy was in a measure responsible. In the 

 later editions, there has been ample time to 

 remedy any shortcomings that may have arisen 

 from this cause, hence it is well to examine 

 with some detail the nature of the changes that 

 have been made in the last edition. The book 

 is divided into two parts ; Part II., a description 

 of the deposits of the respective metals, occu- 

 pying about five-sixths of the total space. In 

 Part I. , which deals with general characteristics, 

 there has been added to Chapter I., on the 

 'Formation of Cavities,' a statement of Van 

 Hise's division of the earth's crust into three 

 zones, one of fracture, one of fracture and 

 fiowage combined, and one of flowage alone ; 

 also si.'c pages on 'Underground Circulation,' 

 but nothing to the very brief mention of ' Re- 

 placement as a mode of deposition.' In Chap- 

 ter III., on 'Minerals and their source,' there 

 has been added a paragraph on the association 

 of certain metals with certain rocks, and one 

 on secondary migrations of vein materials, with 

 references to De Launay's recently expressed 

 views. In Chapter VI., on the 'Classification 

 of Ore Deposit,' the author has elaborated the 

 discussion of his own system ; especially in the 

 direction of magmatic differentiation, relegating 

 the descriptions af other systems to an appendix 

 at the close of the work ; the other three chap- 

 ters are practically unchanged. 



It is in the descriptions in Part II. that the 

 most changes have been made, and these have 

 been mainly as insertions of new paragraphs, 

 so that the statement on the title page that the 

 volume has been ' entirely rewritten,' for which 

 the publishers are evidently responsible, is 

 hardly justified. The actual increase in the 

 number of pages is one hundred and eleven, 

 but this is in considerable part due to larger 

 type. It has evidently been considered im- 

 portant to preserve, as far as possible, the same 

 relative numbering of paragraphs in this as in 

 former editions ; new matter is largely taken 

 from new publications of Government surveys, 

 and from papers in the transactions of the 



American Institute of Mining Engineers. The 

 following are the more important changes in 

 order of chapters : 



In descriptions of ' Iron Deposits ' important 

 enlargements are made from the work of Van 

 Hise and his associates in the Lake Superior 

 region and from the author's studies in the Adi- 

 rondacks. Under ' Copper Ores' the description 

 of the Ducktown and Butte deposits have been 

 largely rewritten, and those on the ' Lake Su- 

 perior Deposits ' have been elaborated ; men- 

 tion is made of some in Idaho. Additions have 

 been made to the discussions of the Lead and 

 Zinc Deposits of the Mississippi Valley from the 

 reports of Winslow and Jenney; in the chapter 

 on 'Zinc alone,' no change is perceptible. 

 Under ' Lead and Silver ' new descriptions are 

 given of the Teumile, Eagle River and Aspen 

 districts in Colorado (the latter rather inade- 

 quate), and under ' Silver and Gold ' of the 

 Telluride, Custer County and Cripple Creek 

 districts, in the same State. Lender the same 

 head, hitherto unpublished data is given from 

 a paper by J. D. Irving on the Black Hills' 

 Deposits, which, like those of Cripple Creek, 

 are more properly classed under ' Gold alone.' 

 New data as to Montana, Idaho and L^tah, are 

 added on the authority of Weed, Liudgren and 

 Spurr, respectively. Descriptions of the ' Gold 

 Deposits of the Pacific Slope ' are very largelj' 

 rewritten from the reports of Lindgren, Becker, 

 Turner and others. Under the heading ' Gold 

 elsewhere in the United States and Canada,' 

 the gold deposits of the Appalachians, which 

 have been barely noticed before, are briefly de- 

 scribed, mainly from Becker's report ; but of 

 the eight pages of text fully one- half are occu- 

 pied by references. Eleven pages are given to 

 Alaska and British Columbia, with notes on 

 Nova Scotia. About eighteen paragraphs have 

 been added to the chapter on the ' Lesser 

 Metals ' in which those that bear upon the 

 theory of magmatic separation are especially 

 prominent. 



The improvement in the illustrations of the 

 volume is most marked, as there were very infer- 

 ior reproductions in former editions ; some of the 

 poorest have been eliminated, and the half-tone 

 prints, both old and new, are of remarkably 

 improved quality, though some still leave much 



