CONTEXTS. 



Page 



Art. LVIII. — Subdivisions in Archaean History ; by J. D. 



Daxa .._■_ 455 



LI.X. — Electrical Discharges through poor Vacua, and on 

 Coronoidal Discharges ; by M. I. Pupix. With Plate 

 XIV .:... 465 



LX. — Rubidium and Potassium Trihalides; by H. L. Wells 

 and H. L. Wheeler. With their Crystallography ; by 

 S. L. Pexfield . 475 



LXL— Clinton Iron Ore; by C. H. Smyth, Jr.. .... 487 



LXII. — Wilde's Explication of the Secular Variation Phe- 

 nomenon of Terrestrial Magnetism ; by L. A. Bauer.. 496 



LXIII. — Josephinite, a new Nickel-Iron ; by W. H. Mel- 

 ville . _ 509 



LXIV. — Fibrous Intergrowth of Augite and Plagioclase, re- 

 sembling a reaction rim, in a Minnesota Gabbro ; by W. 

 S. Bayley . ' 515 



LXV. — Method for the Determination of Barium in the pres- 

 ence of Calcium and Magnesium ; by F. W. Mar . 521 



LXVI. — Note on the Absorption of Radiant Heat by Alum ; 



by C. C. Hltchixs ... 526 



LXVIL— Disruption of the Silver Haloid Molecule by Me- 

 chanical Force ; by M. Carey Lea 52 7 



Appendix.— LXVIII. — Notes on Triassic Dinosauria; by O. 



C. Marsh. With Plates XV, XVI, and XVII ... 543 



SCIENTIFIC INTELLIGENCE. 



Chemistry and .PAj/sfcs.— Polarization of Platinum by Oxygen and Hydrogen. 

 Markofsky. 531. — Basicity of Phosphoric Acid. D. Berthelot. 532.— Occlu- 

 sion of Hydrogen by Lead and other metals. Newmann and Streixtz : Princi- 

 ples of Chemistry. P. Mendeleeff, 533. — Manual of Chemical Technology, by 



. Rudolf von Wagner. W. Crookes and F. Fischer: Laboratory of Chemistry 

 J. E. Armstrong and J. H. Norton, 535. — Lhtersuchungeu uber die Aus- 

 breitung der elektrischen Kraft. H. Hertz, 335. — Torlesugen uber Maxwell's 

 Theorie der Elektricitat und des Lichtes, L. Boltzjiaxx. 536. 



Geology and Naiwal History. — A Summary Description of the Geology of Penn- 

 sylvania. J. P. Lesley. 536. — Fossil Botany, H. Graf zc Solms-Laubach and 

 H. E. F. Garxsey and I. Bayley, 537. — Ueber einige carbone Pflanzenreste 

 aus der Argentihischen Republik, L. Szajxocha : Cambrian of Sardinia, J. G. 

 Borxemaxx. 538. — Fossils in the St. Peter's Sandstone. F. W. Saxdesox: Cor- 

 relation Papers. W. B. Clark: Glacier Rock-crushing. W. G. Tight: System 

 of Mineralogy of J. D. Dana, E. S. Dana, 539. — -Supposed occurrence of Plati- 

 num in North Carolina, F. P. Texable: Summary of Progress in Mineralogy 

 and Petrographv. "W. S. Bayley: Gay-lussite- from San Bernardino Co., CaL, 

 H. G. Hanks, 540. 



Miscellaneous Scientific Intelligence. — Report of the Smithsonian Institution for 

 1S90. 540. — Boston Society of Natural History: Proceedings of the Colorado 

 Scientific Society, 541. — Yolcano of Kilauea, Hawaii: Physiograplry J. Spen- 

 CER : Universal English-German and German-English Dietionarv, F. Flugel : 

 The Ward Collection of«Meteorites. 542. 





