CONTENTS. Vll 



NuimlDer 227. 



Page 



Art. XXXII. — Stokes Method for the Determination of Py- 



rite and Marcasite; by E. T. Allen and J. L. Crenshaw 371 



XXXIII. — Effect of Temperature and Acidity in the Forma- 

 tion of Marcasite (FeS 2 ) and Wurtzite (ZnS); A Contri- 

 bution to the Genesis of Unstable Forms; by E. T. 

 Allen and J. L. Crenshaw. Microscopic Study; by 

 H. E. Merwin - 393 



XXXIV. — Observations on Craigton Lake; by F. Leverett 432 



XXXV. — Searlesite, a new mineral; by E. S. Larsen and 



W. B. Hicks 437 



XXXVI. — Occurrence of Unusually Large Bowlders in 



Gravel Deposits ; by J. L. Rich 441 



XXXVII. — Original Color Markings of two species of Car- 

 boniferous Gastropods; by P. V. Round y. (With Plate 

 III) _. _ ._. 446 



XXXVIIL— Was the Pterophyllum Foliage Transformed 



into the Leafy Blades of Dicotyls ? by G. R. Wieland 451 



XXXIX. — Unios in the Triassic of Massachusetts; by 



E. L. Troxell . _ 460 



XL. — New Locality for Castoroides; by B. Smith __ 463 



XLI. — Notes on Arctic Paleozoic Fossils; by C. Schuchert 467 



SCIENTIFIC INTELLIGENCE. 



Chemistry and Physics — Radium-Uranium Eatio in Carnotites, S. C. Lind 

 and C. F. Whittemore, 477. — New Method for the Precise Standardiza- 

 tion of Hydrochloric Acid Solutions, L. W. Andrews: Introductory Notes 

 on Quantitative Chemical Analysis, C. W. Foctlk: Elementary Household 

 Chemistry, J. F. Snell, 478. — Popular Treatise on the Colloids in the 

 Industrial Arts (Kurt Arndt), N E. Katz: Fixation of Atmospheric Nitro- 

 gen, J Knox: Lehrbuch der physikalischen Chemie, K. Jellinek, 479. — 

 Complex Ions in Aqueous Solutions, A. Jaques, 480. — Lichtmessungen 

 mit Selen, W. Jaenichen : Crystalline Structure of Copper, W. L. Bragg, 

 481. 



Geology and Mineralogy — Deseado Formation of Patagonia, F. B. Loomis, 

 482.— Publications of the United States Geological Survey, G. O. Smith,. 

 484. — Minerals of California : Gems and Precious Stones in 1913, 487. 



Miscellaneous Scientific Intelligence — The Ring Burner of Dr. Wolcott Gibbs, 

 W. G. Levison: Publications of the Carnegie Institution of Washington, 

 489. 



Obituary — W. H. Gaskell: H. J. Johnston-Lavis: R. J. Anderson: W. L_ 

 Dudley, 490. 



