CONTENTS. 



Page 



Art. XL — History of Changes in the Mt. Loa Craters; by 



J. D. Daxa. Part II, on Mokuaweoweo 81 



XII— The Fayette County, Texas, Meteorite; by J. E. Whit- 

 field and G. P. Merrill. 113 



XIII. — Evidence of the Fossil Plants as to the Age of the 



Potomac Formation ; by Lester F. Ward ._ .119 



XIV. — Experiments on the Effect of Magnetic Force on the 

 Equipotenlial Lines of an Electric Current; by E. H. 

 Hall _ ._ 131 



XV. — Analyses of the Waters of some American Alkali 



Lakes; by Thomas M. Chatard 146 



SCIENTIFIC INTELLIGENCE. 



Chemistry and Physics. — On the Molecular weight of Nitrogen peroxide. Ramsay. 

 150. — Index of refraction of metals, A. Kuxdt, 151. — Resistance of square bars 

 to Torsion. T. I. Dewar: Latent heat of Evaporation of Water. Dr. Dieterici: 

 Electrolysis by alternating currents of Electricity, Maxecyrier and J. Chap- 

 puis, 152. — Electro-chemical Radiophone, Chaperox and Mercadier, 153. 



Geology and Mineralogy. — On the Black Hills of Dakota, W. 0. Crosby : Annual 

 Report of the Geologieal Survey of Pennslyvania for 1886, 153. — Geological 

 and Scientific Bulletin: The Genealogical Tree. J. \Y. Jcdd: Estudo sobre os 

 Bilobites e outros Fosseis das Quartsites cla Base do systema Silurico de Portu- 

 gal, J. F. N. Delgado : British Petrography with special reference to the Igne- 

 ous Rocks. J. J. Hahris Teall. 154. — Brief notices of some recently described 

 minerals. 156. — Mineralogical Notes, (1) Yesuvianite from Newbury. Mass.. W. 

 0. Crosby and James T. Greeley; ci) Gahnite from Rowe, Mass., W. 0. 

 Crosby and Charles L. Browx: Brazilian Meteorites: Note on the Locality 

 of the Santa Catharina Meteorite. 157. — The Bendego Meteorite, 158. 



Botany. — Notices of recent contributions to Vegetable Physiology: (1) A. H. de 

 Vries's studies of Glycerin in its relations to certain tissues. 158 : (2) Assimila- 

 tion by colored and variegated leaves, Engelmaxx. 159. — (3) Hough's Ameri- 

 can Woods, Part 1. Rometn B. Hough. 160. 



Obituary. — Amos H. YTorthex. 160. 



ERRATUM. 

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