IV CONTENTS. 



N"UHi"ber 212. 



Page 



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



J.D.Dana. 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 



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

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

 Hall 131 



XY. — Analyses of the Waters of some American Alkali 



Lakes; by Thomas M. Chatard___ ___ 146 



SCIENTIFIC INTELLIGENCE. 



Chemistry om<1 Physics. — On the Molecular weight of Nitrogen peroxide, Ramsay, 

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

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

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

 puis, 152. — Electro-chemical Radiophone, Chaperon 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 da Base do sy sterna Silurico de Portu- 

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

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

 minerals, 156. — Mineralogical Notes, (1) Yesuvhmite from N"ewbury, Mass.. W. 

 0. Crosby and James T. Greeley ; (2) Gahnite from Rowe, Mass., W. 0. 

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

 of the Santa Catharina Meteorite, 15 7. — The Bendego Meteorite, 158. 



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

 Yries's studies of Glycerin in its relations to certain tissues, 158; (2) Assimila- 

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

 can Woods, Part 1, Romeyn B. Hough, 1G0. 



Obituary. —Amos H. AVorthex, 160. 



