PREFATORY NOTE. 
In the following pages there have been brought together a variety of 
chemical and mineralogical researches, which were carried out in the 
laboratory of the United States Geological Survey between July 1, 
1893, and July 1, 1899. In one sense the bulletin is a continuation of 
the series represented by Bulletins Nos. 9, 42, 55, 60, 04, 78, 90, and 113; 
only, unlike them, it reports no miscellaneous analyses. The latter 
represent by far the larger part of the work done in the laboratory; 
but most of them are published in other form, in connection with the 
geological investigations to which they relate. Their repetition here is 
unnecessary. 
F. W. O. 
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