CONTENTS. Vll 



Niimlber 161. 



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 D. 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. 



Cockerele ... . 381 



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



Griggs ---;---. .- - : 3 8 8 



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 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 Eadio-active Elements, Stromholm and 

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

 Copatjx and Boiteau, 404. — Canal Rays, J. Stark and W. Steubing : 

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

 Penetrability in the Atmosphere, T. Wulf : Use of Radiometer for Observ- 

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

 Popularly Explained. W. W. Massie and C. R. Underbill : Introduction 

 to the Science of Radio-activity, C. W. Raffety, 406. 



Geology and Natural History — Publications 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 g^ologique 

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

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

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

 Geology of the Taylorsville Region, 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 Rocks and Fos- 

 sils, C. D. Walcott : Devonian Fishes of Iowa, C. R. 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. 



