VI CONTENTS. 



Numlber 58. 



Page 

 Art. XXV. — Notes on the Colorado Canyon District; by 



W. M. Davis 251 



XXVI. — Determination of Minerals in thin Rock-sections by 

 their maximum Birefringence ; by L. V. Pirsson and 

 H. H. Robinson . 260 



XXVII.— Studies in Cyperacese; by T. Holm 266 



XXVIII. — Experiments on High Electrical Resistance; by 



O. N. Rood 285 



XXIX. — Occurrences of Corundum in North Carolina ; by 



J.H.Pratt 295 



XXX. — Products of the Explosion of Acetylene, and of Mix- 

 tures of Acetylene and Nitrogen ; by W. G. Mixtrr .. 299 



XXXI. — Scapolite Rocks from Alaska; by J. E. Spurr 310 



XXXII. — Qualitative Separation of Nickel from Cobalt by 

 the action of Ammonium Hydroxide on the Ferricyan- 

 ides; by P. E. Browning 316 



SCIENTIFIC INTELLIGENCE. 



Physics — Radio-activity of Uranium, W. Crookes, 318. — Electrical conductivity 

 of Gases traversed by Cathode Rays, J. C. McLennan, 319. — Kleiner Leitfaden 

 der Praktischen Physik, Friedeich Kohlrausch: Photometrical Measure- 

 ments and Manual for the General Practice of Photometry, W. M. Stine, 320. 



Geology and Mineralogy — Status of the Mesozoic Floras of the United States, L. 

 F. "Ward, 320.— La Flore Wealdienne de Bernissart, A. C. Seward, 323. — 

 Notes on Some Jurassic Plants in the Manchester Museum, A. C. Seward : 

 "The Maidenhair Tree," A. C. Seward: New Minerals from Greenland, 323. 



Obituary — James Edward Keeler, 325. 



