CONTEXTS. 



Page 



Art. XII.— Cheapest Form of Light, from studies at the Alle- 

 gheny Observatory ; bv S. P. Langley and F. W. Very. 

 With Plates III, IV and V 97 



XIII. — Contributions to Mineralogy, Xo. 48; by F. A. Genth 114 



XIV. — Curious Occurrence of Vivianite ; by Wm.L. Dudley 120 



XV. — Classification of the Glacial Sediments of Maine; by 



George H. Stone 122 



XVI. — The Direct determination of Bromine in mixtures of 

 alkaline Bromides and Iodides; by F. A. Gooch and 

 J. R. Ensign _■ 145 



XVII. — Some Lower Silurian Graptolites from Northern 



Maine ; by W. W. Dodge 153 



XVIII. — Siderite-basins of the Hudson River Epoch ; by 



James P. Kimball. With Plate VI 155 



XIX. — New variety of Zinc Sulphide from Cherokee County, 



Kansas; by James D. Robertson .. 160 



XX. — Two new Meteoric Irons ; by F. P. Venable 161 



XXI. — Appendix. — Notice of some Extiuct Testudinata ; by 



O. C. Marsh. (With Plates VII and VIII . _ 177 



SCIENTIFIC INTELLIGENCE. 



Chemistry and Physics. — Nature of Solutions. 'Picketing, 163. — Molecular- Mass 

 of Iodine, of Phosphorus, and of Sulphur in Solution. Beckmann: Conditions 

 of Equilibrium between Electrolytes. Arrhenius, 164. — Coincidences between 

 lines of different spectra, Runge : Hertz's experiments, L. Boltzman : Station- 

 ary light waves, 0. Wiener, 165. — Electrical Oscillations in air, J. Trowbridge 

 and W. C. Sabine, 166. 



Geology and Mineralogy. — The American Committee of the International Congress 

 of Geologists. 166. — Professor W"m. M. Fontaine on the Potomac or Younger 

 Mesozoic Flora, 168. — Eruption of Bandai-san, 169. — Die Miueralien der 

 Syenitpegmatitgange der Siidnorwegischen Augit-und Nephelinsyenite, W. C. 

 Brogger, 170. — Catalogue of Minerals for sale by G-eorge L. English & Co., 171. 



Botany. — Catalogue of Plants found in New Jersey, N. L. Britton, 171. — List of 

 Plants: Preparation of sections for the study of the development of organs, 

 Goethart, 172. — Ascent of colored liquids in living plants. 'Wieler: Analyti- 

 cal Key to the Genera and species of North American Mosses, C. F. Barnes: 

 Structural and Systematic Botany, D. H. Campbell, 173. 



Astronomy. — Spectrum of the Nebula in Orion, W. Huggins and Mrs. Huggins, 

 173. — New Group of Lines in the Photographic Spectrum of Sirius, W. Hug- 

 gins, 175. 



Miscellaneous Scientific Intelligence. — American Association for the Advancement of 

 Science, 175. — Hailstones of peculiar form, 0. W. Huntington: Oswald's 

 Klassiker der exacten "Wissenschaften, 176. 



Obituary. — Christian Henry Frederick Peters, 176. 



Erratum. — Fig. 3, Plate III, has been omitted, hence the references to it on 

 pp. 105, 106 are to be struck out. 



