CONTENTS. 



Page 



Art. I. — Glacial Cirques near Mount Washington ; by J. W. 



GoLDTHWAIT '. _ 1 



II. — Improved Method of Cleaning Diatoms; by J. M. Blake 19 



III. — A new Occurrence of Silver, Copper, and Cobalt Min- 

 erals in Mexico ; by F. R. Van Horn 23 



IV. — Vertebrate Footprints in the Lower Permian of Kansas ; 



by R. L. Moodie 31 



V. — Dinosaurs of East Africa ; by C. Schuchert 34 



VI. — Recombination of Ions Produced by Rontgen Rays; 



by S. J. Plimpton _ _____ 39 



VII. — The Use of Selenic Acid in the Determination of 

 Bromine Associated with Chlorine in Haloid Salts ; by 

 F. A. Gooch and P. L, Blumenthal 54 



VIII. — Oblique Illumination in Petrographic Microscope 



Work; by F. E. Wright 63 



IX. — Notes on the Silurian Limestone of Milesburg Gap, 



near Bellefonte, Penn. ; by T. C. Brown 83 



X. — Cerussite Twin from the Mammoth Mine, Pinal County, 



Arizona ; by J. E. Pogue 90 



XL — The Preparation of Selenic Acid and Sodium Selenate 

 for Use as Reagents in the Determination of Bromine in 

 Haloid Salts ; by P. Lee Blumenthal 93 



SCIENTIFIC INTELLIGENCE. 



Chemistry and Physics — Quantitative Determination of Copper : Dissocia- 

 tion of Phosphorus Vapor: Iron Contamination of Laboratory Samples, 

 97. —Volumetric Determination of Arsenic Acid: Modern Inorganic 

 Chemistry, 98. — Industrial Inorganic Chemistry : Discharge between Con- 

 centric Cylinders in Gases at Low Pressures, 99. — The Crookes Dark 

 Space, Aston. —Multiply-charged Atoms, 101. — Handbuch der Spectro- 

 scopie, Kayser, 102. — Circulations Atmospheriqu.es, etc., Vjalay, 103.— 

 Magneto and Electric Ignition : Physics, Watson : Gli Elettroni nei Metalli, 

 104. 



Geology and Mineralogy — 33d Ann. Report of the Director of the U. S. 

 Geol. Survey, 105. — W. Virginia Geol. Survey, Hennen : Illinois State 

 Geol. Survey, 106. — Geol. Survey of Pennsylvania : Eeport of Flood Com- 

 mission of Pittsburgh, 107. — Trias of the Himalayas, 108. —Origin and 

 Antiquity of Man, G. F. Wright : Prehistoric Man, Duckworth, 110. — 

 Early Man in America, A. Hrdlicka : Geology of Park City District, Utah, 

 111. — Oil-Finding : Examination of Prospects : Building Stones and. Clay- 

 Products, Ries, 112. — Mineralogy, A. H. Phillips, 113. 



Zoology — Comparative Anatomy of Vertebrates, 113. — Study of the Protozoa: 

 Ascidians of New England and British Provinces, W. G. Van Name, 

 114. —The Early Naturalists, 115. — Manual of Biology: Michigan Bird 

 Life, 116. 



Miscellaneous Scientific Intelligence — Protein Metabolism : Researches on 

 Cellulose, 116. — Constitution of the Proteins : Microbes and Toxins : 

 Nutritional Physiology, 117. — Oxidations and Reductions in the Body : 

 Soil Conditions and Plant Growth : Protein Element in Nutrition, 118. — 

 Principles of Hygiene : Hasheesh : Geol. Society of America, 119. — 

 American Association, 120. 



Obituary — G. H. Darwin : E. J. Loomis : E. Smith : W. A. Buckhout : 

 J. M. Van Vleck : R. H. Traquair : W. F. Kirby, 120. . 



