ADVERTISEMENT. Ill 
B 220. Mineral analyses from the laboratories of the United States Geological survey, 1880 to 1903, 
tabulated by F. W. Clarke, chief chemist. 1903. L19 pp. 
B 228. Analyses of rocks from the laboratory of the United states Geological Survey, L880 to L903, 
tabulated by F. W. Clarke, chief chemist. 1904. 375 pp. 
IT 28. The superior analyses of igneous rocks from Roth's Tabellen, 1869 to L884, arranged according 
to the quantitative system of classification, by B.S.Washington. 1904. 68 pp. 
B 239. Rock cleavage; by C.K. Leith. 1904. 216 pp., 27 pis. 
B 241. Experiments on schistosity and slaty cleavage, by G. F. Becker. 1904. 34 pp., 7 pis. 
B 253. Comparison "of wet and crucible-fire methods for the assay of gold telluride ores, with notes 
on the errors occurring in the operations of fire assay and parting, by YV. F. Billebrand and 
E. T. Allen. 1905. 33 pp. 
B 261. Preliminary report of the operations of the coal-testing plant of the United States Geological 
Survey at the Louisiana Purchase Exposition, St. Louis, Mo., 1904; E. W. Parker,.!. A. Holmes, 
M. R. Campbell, committee in charge. 1905. 172 pp. 
B 262. Contributions to mineralogy from the United States Geological Survey, by F.W. Clarke, W. F. 
Hillebrand, F. L. Ransome, S. L. Penfield, Waldemar Lindgren, George Steiger, and \\ . T. 
Schaller. 1905. 147 pp. 
Correspondence should be addressed to — 
The Director, 
United States Geological Survey, 
Washington-, D. C. 
May, 1905. 
