CONTENTS. 



Page 



Samuel Lewis Penfield 353 



Art. XXXIV. — Conductivity of Air in an Intense Electric 

 Field and the Siemens Ozone Generator ; by A. W. 

 Ewell .... 368 



XXXV. — Hydrolysis of Salts of Ammonium in the Presence 



of Iodides and Iodates ; by S. E. Moody . „ 379 



XXXVI. — Estimation of Fluorine Iodometrically ; by A. 



Hileman _ 383 



XXXVIL— Minerals of the Composition MgSi0 3 ; A Case of 

 Tetramorphism ; by E. T. Allen, F. E. WEiGHT'and 

 J.K.Clement .__ __. , _.. 385 



XXXVIII. — Contributions to the Geology of New Hamp- 

 shire : No. II, Petrography of the Belknap Mountains ; 

 by L. V. Plrsson and H. S. Washington 439 



SCIENTIFIC INTELLIGENCE. 



Chemistry and Physics — Preparation of Pure Ethyl Alcohol and Some of its 

 ' Properties, L. W. Winkler : Double Salts of Mercuric Chloride with the 

 Alkali Chlorides, Foote and Levy, 458. — Atomic Weight of Tantalum, 

 Hinrichson and Sahlbom : Isomorphism of Northupite and Tychite, 

 A. de Schulten, 459. — Separation of Antimony and Tin, A. Czerwek : 

 Lehrbuch der Allgemeinen Chemie, W. Ostwald : Eadio-Activity, Becker, 

 etc., 460. — Velocity of X-Rays, E. Marx, 461.— Formation of Ozone from 

 Oxygen and Atmospheric Air by Silent Discharges of Electricity, E. War- 

 burg and G. Leithauser : Oxidation of Nitrogen by Silent Discharges in 

 Atmospheric Air, E. Warburg and G. Leithauser : Influence of Moisture 

 and Temperature on the Ozonizing of Oxygen and of Atmospheric Air, E. 

 Warburg and G. Leithauser, 462. 



Geology and Mineralogy — Tenth International Geological Congress at Mexico 

 City, 463. — Descriptive Catalogue of the Tertiary Vertebrata of the Fayum, 

 Egypt, 465. — Geology of the Owl Creek Mountains with Notes on Resources 

 of Adjoining Regions in the Ceded Portion of the Shoshone Indian Reser- 

 vation, Wyoming, N. H. Darton : Copper Deposits of the Robinson 

 Mining District, Nevada, A. C. Lawson, 467. — Montana Lobe of the Kee- 

 watin Ice Sheet, F. H. H. Calhoun : Les Lac Alpins Suisses : Etude 

 Chimique et Physique, F.-E. Bourcart : Species of Botryocrinus, F. A. 

 Bather : Soils, their Formation, Properties, Composition and Relations 

 to Climate and Plant Growth in the Humid and Arid Regions, E. W., 

 Hilgard, 468. — Brief Notices of some recently described Minerals, 469. 



Astronomy — Parallax Investigation of 162 Stars, Mainly of Large Proper 

 Motion, 471. — Publications of the United States Naval Observatory, 475. 



Miscellaneous Scientific Intelligence — A Text-Book in General Zoology, H. R. 

 Linville and H. A. Kelly : Illustrations of British Blood-sucking Flies, 

 with notes, E. E. Austen : Synonymic Catalogue of Homoptera. Part I. 

 Cicadidae, W. L. Distant, 476. 



Obituary— Dn. Ludwig Boltzmann, 476. 



