CONTENTS. 



Number 261. 



Page. 



Art. XXV. — The Gulf of Mexico as a Measure of Isostasy ; 



by W. J. McGee 177 



XXVI.— Persistence of Vision ; by E. S. Ferry •_ 192 



XXVIL— Kilauea in April, 1892; by S. E. Bishop .. 207 



XXVIII. — The Devonian System of Eastern Pennsylvania; 



by C. S. Prosser 210 



XXIX. — Caesium-Mercuric Halides; by H. L. Wells 221 



XXX. — Relations of the Lauren tian and Huronian on the 



North Side of Lake Huron; by A. E. Barlow 236 



XXXI. — Some Convenient Forms of Laboratory Apparatus ; 



by F. A. Gooch ■_, 239 



XXXII. — Note on the change of electric conductivity ob- 

 served in rock magmas of different composition on pass- 

 ing from liquid to solid ; by Carl Barus and J. P. 



Iddings . 242 



XXXIII. — Estimation and Dehydration of Silver Oxide; 



by M. Carey Lea 249 



SCIENTIFIC INTELLIGENCE. 



Chemistry and Physics — Phenomena of Coal-dust Explosions, Thorpe. 250. — 

 Certain new forms of Carbon, Luzi, 251. — Quinite, the simplest Sugar of the 

 Inosite group, Baeter: Relation between the Color of Compounds and their 

 Chemical Constitution. Schutze, 252. — Free Hydroxylamine, Lobrt de Bruyne: 

 Physical and chemical phenomena under the influence of very low temperatures, 

 M. Raoul Pictet, 253. — New method of determining the specific inductive 

 capacity of a dielectric, F. T. Trouton and W. E. Lilly: Action of the Electric 

 discharge on Gases and Vapors, C. Ludeking : Ratio between the Electromagnetic 

 and Electrostatic Units, M. H. Abraham : Influence of Electrification on Cloud 

 Condensation, J. Aitken, 254. — Thermal variation of viscosity and of electrolytic 

 resistance, C. Barus : Outlines of Theoretical Chemistry, L Meyer, 255. — 

 Theoretical Mechanics, J. Spencer: Negativ-Retouche nach Kunst- und Natur- 

 gesetzen, Hans Arnold, 256. 



Geology and Mineralogy — Upraised Coral Islands off New Guinea, 256. — Origin of 

 Igneous Rocks, J. P. Lddings, 257. — Bulletin of the Philosophical Society of 

 Washington, Dutton on Isostasy, 258; — Siliceous bed consisting of Diatoms, 

 Radiolarians and Sponge-spicules in New Zealand : Preliminary Catalogue of the 

 systematic Collections in Economic Geology and Metallurgy in the U. S. 

 National Museum, F. P. Dewey : Palaeontology of the Cretaceous formation on 

 Staten Island, A. Hollick, 259. — Untersuchungen fiber fossile Holzer Schwe- 

 dens, H. Conwentz: Penfieldite, a new species, F. A. Genth, 260. — Brief 

 notices of some recently described minerals, 261. 



Miscellaneous Scientific Intelligence — Transactions of the Wisconsin Academ)' of 

 Sciences. Arts and Letters : Dictionary of Altitudes in the United States, H, 

 Gannett. 262. 



