CONTENTS. V 



Number 273. 



Page 



Art. XXIIL— Fireball of January 13th, 1893. By H. A. 



Newton. (With Plate III) 161 



XX1Y. — Photometric Method which is independent of Color; 



by O. N. Rood. .. 173 



XXV. — Actinolite-Magnetite Schists from the Mesabe Iron 



Range, in Northeastern Minnesota; by W. S. Bayley 176 



XXVI.— Double Salts of Lead Tetrachloride; by H. L. 



Wells 180 



XXVII. — Method for the Quantitative Determination of 

 Caesium, and the Preparation of pure Caesium and Ru- 

 bidium Compounds ; by H. L. Wells 186 



XXVIII. — Peculiar Halides of Potassium and Lead ; by II. 



L. Wells 190 



XXIX. — Oscillations of Lightning discharges and of the 



Aurora Borealis; by J. Trowbridge. (With Plate IV) 195 

 XXX. — The Auriferous Veins of Meadow Lake, California; 



by W. Lindgrex _ __ 201 



XXXI. — The Stability of Standard Solutions of Tartar 



Emetic; by H. Gruener. _ 206 



XXXII. — Description of Rowlandite; by W. E. Hidden 



and W. F. Uillebraxd 208 



XXXIII. — The Upper Hamilton and Portage Stages of Cen- 

 tral and Eastern New York; by C. S. Prosser 212 



XXXIV. — Estimation of Chlorates and Nitrates, and of 



Nitrites and Nitrates, in one operation ; by C. F. 



Roberts 231 



XXXV.— Alphonse DeCandolle; by G. L. Goodale 236 



SCIENTIFIC INTELLIGENCE 



Geology and Natural History — Minnesota Geological and Natural History Sur- 

 vey: Paleontology of New York, J. Hall and J. M. Clarke, 239. — Salt and 

 Gypsum Industries of New York, F. J. H. Merrill: Bionomie des Meeres, 

 J. Walther: North American Fauna, No. 7, 240. 



