ben at 
REVIEWS 435 
the Institute, Mr. R. W. Raymond, it is characteristic of his modesty 
that his name appears in the volume only among those of the con- 
tributors. Nevertheless, in preparing the volume, Mr. Raymond has 
performed a service which his fellow-workers will more and more 
appreciate as the work comes to assume its rightful place; that of the 
standard statement of modern views on ore deposits. 
Covering, as it does, practically a decade of discussion, and being 
made up, as it is, of the statements of so many workers, it is in a pecu- 
liar degree a summary of present belief with just enough of discarded 
theory to give a proper perspective. The period from 1893 to igor 
has been particularly fruitful in the study of ore deposits, and, as is so 
often true, much of the discussion which has led to the clearing up of 
certain phases at least of the problem of the genesis of ores, came from 
the clear and unequivocal statement of an extremist; one, furthermore, 
whose ideas were radically opposed to those most generally current at 
the time. Up to 1893 American scientific opinion was strongly com- 
mitted to the doctrine of lateral secretion ; not, however, exactly in the 
sense proposed by Sandberger in his famous treatise* defining that 
doctrine. A characteristic expression of the broader American view 
is that of Emmons in his report on the Leadville district.* According 
to this view, ore deposits in general represent concentrations made by 
underground waters, the material being derived from the leaching of 
the country rock, not necessarily of the immediate vicinity. The 
waters were believed to be meteoric in origin, and more or less closely 
connected with the ordinary surface circulation. 
In 1893 Professor PoSepny, with charming spirit, and fortifying 
his argument with many illustrations drawn from notes accumulated 
during a long and intimate study of ore deposits, combated this view 
most vigorously. Beginning with a clear and accurate analysis of the 
subterranean water circulation, he discriminated sharply a vadose or 
shallow circulation from a deep circulation, basing the distinction 
mainly upon the chemical constitution and effects of the two waters ; 
. a difference already clearly recognized and made use of in America by 
both Le Conte and Chamberlain, but not generally recognized as fully 
as it deserved. As characteristic of the difference between the waters 
of the two circulations, and most significant for purposes of the dis- 
cussion, it was pointed out that the water of the vadose circulation in 
tUntersuchungen uber Erzgange, Weisbaden, 1885. 
?Monograph XII, U.S. Geol. Surv., Washington, 1886. 
