Index XI-XX, now ready. Price $1.00. 



CONTENTS. 



Art. XXXVI. — Radio-Activity of the Salts of Radium ; 



by B. B. Boltvvood " s 409 



XXXVII.— Radio-Activity of Thorium Minerals and Salts ; 



by B. B. Boltwood . 415 



XXXVIII.— Radio-activity of Thorium ; by H. M. Dadou- 



RIAN --- ----- 427 



XXXIX. — The Radio-activity and Composition of Thorium 



Compounds ; by H. N". McCoy and W. H. Ross 433 



XL. — Prorosmarus alleni, a new genus and species of Walrus 

 from the Upper Miocene of Yorktown, Virginia ; by 

 E. W. Berry and W. K. Gregory. 444 



XLI. — A new form of "Container" for use in Museums of 



Economic Botany ; by G. L. Gooda.le-_ 451 



XLII. — Filter Tubes for Collection of Precipitates on Asbes- 

 tos by S. L. Pex field and W. M. Bradley . . - 453 



XLIII. — Age and Type Localities of the Supposed Jurassic 



Fossils collected by Fremont in 1843 ; by A. C. Veatch 457 



XLIV. — Certain Suggestions by J. Willard Gibbs on Geo- 

 physical Research 461 



SCIENTIFIC INTELLIGENCE . 



Chemistry and Physics — Molecular Weight of Silver Vapor, Wartexberg : 

 Carbon Oxybroraide, A. von Bartel, 463. — Industrial Preparation of Cal- 

 cium Hydride. Jaubert : Synthesis of Cyanogen, etc., from the Elements, 

 T. Wallis : Gaseous Hydride of Calcium in Acetylene, Hoffmeister, 464. 

 — Electrical Nature of Matter and Radioactivity. H. C. Jones : Energy, 

 Duration, Damping and Eesistance of Condenser Sparks, A. Heydweil- 

 ler : Magnetic Eelations of Powdered Iron of Various Densities, W. 

 Trenkle : Spectrum of the High Tension Flaming Discharge, B. Wal- 

 ter, 465. — Photography of a Eadium Crystal by its Own Light, B. Wal- 

 ter : Ions, Electrons, Corpuscules, 466. — Phj'sical Measurements, 467. 



Geology and Natural History — Contributions to the History of American 

 Geology, G. P. Merrill, 467. — Revision of Paleozoic Insects, A. Hand- 

 lirsch, 468. — Study of James Types of Ordovician and Silurian Bryozoa : 

 Descriptions of Upper Carboniferous Genera and Species [of Ostracoda] : 

 Osteology of Protostega, G. E. Wieland, 469. — Osteology of Diplodocus 

 Marsh. W. J. Holland ; New Ruminant from Pleistocene of New Mexico, 

 J. W. Gidley ; Report on Lead and Zinc Deposits of Wisconsin, 470. — 

 Diamond Pipes and Fissures of South Africa, 471. — Petrogenesis, 472. — 

 Hohlenkunde : Coal Resources of Wyoming : Over de Betrekking van het 

 Bekken der Anthropoiden tot dat van den Mensch, 473. — Glossopteris 

 Flora : Madreporian Corals, 474. — British Freshwater Rhizopoda and Heli- 

 ozoa : Harvard Botanical Station in Cuba, 475. — Plant Response, 476. — 

 British Desmidiaceae : Pflanzenf abel, 477. 



Miscellaneous Scientific Intelligence — Bahnbestimmung der Himmelskorper, 

 478. — Report of U. S. Nat. Museum for year ending Juue 30, 1904 : Dyna- 

 mics of Living Matter, 479. — Carnegie Institution of Washington : Brook- 

 lyn Institute of Arts and Sciences, 480. 



Obituary — N. S. Shaler and I. C. Russell. 

 Index to Vol. XXI, 482, 



313 



