CONTENTS. 



Page 

 Art. XXVIII. — Weathering and Erosion as Time Measures ; 



by F. Leverett 349 



XXIX.— Chalk Formations of Northeast Texas ; by C. H. 



Gordon 369 



XXX. — Devonian of Central Missouri ; by I). K. Greger.. 374 

 XXXI. — Volumetric and Gravimetric Estimation of Thal- 

 lium in Alkaline Solution by Means of Potassium 

 Ferricyanide ; by P. E. Browning and H. E. Palmer.. 379 

 XXXII. — Descriptions of Tertiary Insects, VI ; by T. D. A. 



COCKERELL ... 381 



XXXIII. — Divided Lakes in Western Minnesota; by R. F. 



Griggs _ _ ... 388 



XXXIV. — Heat of Formation of Titanium Dioxide, and 



third paper on the Heat of Combination of Acidic Oxides 



with Sodium Oxide ; by W. G. Mixter . I 393 



XXXV. — Note on Crystal Form of Benitoite ; by C. Palache 398 

 XXXVI. — Alamosite, a new Lead Silicate from Mexico ; by 



C. Palache and H. E. Merwin _ 399 



XXXVII. — Absence of Polarization in Artificial Fogs ; by 



C. Barus _ 402 



SCIENTIFIC INTELLIGENCE. 



Chemistry and Physics — Prussian Blue and Turnbull's Blue, Muller and 

 Stanisch : Chemistry of the Badio-active Elements, Stromholm and 

 Svedberg, 403. — Hydrogen Silicides, Lebeau : Determination of Boron, 

 Copaux and Boiteau, 404. — Canal Bays, J. Stark and W. Steubing : 

 Zeeman Effect of Mercury Lines, P. Gmelin : Presence of Bays of High 

 Benetrability in the Atmosphere, T. Wulf : Use of Badiometer for Observ- 

 ing Small Pressures, J. Dessar, 405. — Wireless Telegraphy and Telephony 

 Popularly Explained, W. W. Massie and C. B. Underhill : Introduction 

 to the Science of Badio-activity, C. W. Baffety, 406. 



Geology and Natural History — Bublications of the U. S. Geological Survey, 

 G. O. Smith, 406. — Economic Geology of the Georgetown Quadrangle, 

 Colorado, J. E. Spurr and G. H. Garrey, 408. — Geology of the Gold 

 Fields of British Guiana, J. B. Harrison, 409. — Eruption of Vesuvius in 

 April, 1906, H. J. Johnston-La vis : Essai sur la Constitution geologique 

 de la Cuyane hollandaise (district occidental), H. Van Capelle : Text- 

 Book of Betrology, F. H. Hatch, 410. — Classification of the Plutonic 

 Bocks, F. H. Hatch, 411. — Elements of Optical Mineralogy, Winchell : 

 Geology of the Taylorsville Begion, California, J. S. Diller, 412. — Explo- 

 rations in Turkestan : Glacial Bowlders in the Blaini Formation, India, T. 

 H. Holland : Guadalupian Fauna, G. H. Girty, 413. — Cambrian Sections 

 of the Cordilleran Area, C. D. Walcott : Mount Stephen Bocks and Fos- 

 sils, C. D. Walcott : Devonian Fishes of Iowa, C. B. Eastman, 414. — 

 Unterkiefer des Homo Heidelbergensis aus den Sanden von Mauer bei 

 Heidelberg, O. Schoetensack, 415. — Commercial Products of India, G. 

 Watt, 417.— Forest Flora of New South Wales, J. H. Maiden, 418. 



Miscellaneous Scientific Intelligence — National Academy of Sciences, 418. — 

 Allgemeine Physiologie, M. Verworn : Man in the Light of Evolution, 

 J. M. Tyler, 419. — Harvard College Observatory, E. C. Pickering : Pub- 

 lications of the Allegheny Observatory of the University of Pittsburgh : 

 Brooklyn Institute of Arts and Sciences, 420. 



Obituary — Dr. Persifor Frazer, 420. 



