CONTENTS. 



Nurober 140. 



Page 



Art. IX. — Radio-Activity of Thorium Salts ; by B. B. 



Boltwood ; 93 



X. — Wave-lengths and Structural Relation of Certain Bands 



in the Spectrum of Nitrogen ; by E. E. Lawton . 101 



XI. — Tertiary Peneplain of the Plateau District, and Adja- 

 cent Country, in Arizona aud New Mexico ; by H. H. 

 Robinson _ _ 109 



XII. — Pleat of Combustion of Silicon and Silicon Carbide ; 



by W. G. Mixter 130 



XIII. — Vanadium Sulphide, Patronite, and its Mineral Asso- 

 ciates from Minasragra, Peru; by W. F. Hillebrand__ 141 



XIV. — Mineralogical Notes ; by W. T. Schaixer 152 



XV. — Thermoelectromotive Forces of Potassium and Sodium 



with Platinum and Mercury ; by H. C. Barker 159 



XVI. — Reaction between Potassium Aluminium Sulphate and 

 a Bromide-Bromate Mixture ; by F. A. Gooch and 

 R. W. Osborne 167 



XVII. — Preparation of Formamide from Ethyl-Formate and 

 Ammonium Hydroxide ; by I. K. Phelps and C. D. 

 Deming 173 



XVIII. — Lower Middle Cambrian Transition Fauna from 



Braintree, Mass. ; by H. W. Shimer 176 



SCIENTIFIC INTELLIGENCE. 



Geology and Natural History — Bermuda Islands. Part IV. Geology and 

 Paleontology, A. E. Verrill, 179. — Bermuda Islands. Part V, Section I, 

 A. E. Verrill : Maryland Geological Survey, Calvert County, G. B. 

 Shattuck, B. L. Miller and others, 180. — Maryland Geological Survey, 

 St. Mary's County, G. B. Shattuck, B. L. Miller and others : Geological 

 Survey of India : Brief Descriptions of some recently described New Min- 

 erals, 181. — Chiastolite from Bimbowrie, South Australia, 183. 



Obituary — Professor A. Heilprin, 184. 



